Florida Water Resources Journal - November 2014

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Volume 66 November 2014 Number 11

Florida Water Resources Journal • November 2014 3

News and Features4 Holistic Look at Optimizing Biofilters and the Water Treatment Process—

Jennifer Nyfennegger, Jess Brown, Kara Scheitlin, and Chance Lauderdale

57 Florida Team Wins WEF Student Design Competition

Technical Articles10 Construction Manager At-Risk Implementation for a Water Treatment

Plant Granular Activated Carbon Filtration Project—Edward Alan Ambler,

E. Devan Henderson, and Matt Peterson

24 Disinfection Byproduct Formation Potential Reduction and Hydrogen SulfideTreatment Using Ozone—Greg Taylor, Charles DiGerlando, and Christopher R. Schulz

34 Effects of Backwash Water and Chemical Addition on Biofiltration—Hongxia Lei, Dustin W. Bales, and Maya A. Trotz

46 Treatment of Organic-Laden Surface Water for Total Organic Carbon—Steven J. Duranceau

Education and Training15 FSAWWA Conference32 TREEO Center Training41 FWPCOA Training Calendar45 CEU Challenge

Columns20 Certification Boulevard—Roy Pelletier

21 FSAWWA Speaking Out—Carl R. Larrabee Jr.

22 Technology Spotlight—Roger K. Noack

32 C Factor—Jeff Poteet

54 FWEA Focus—Kart Vaith and Lisa Prieto

55 Reader Profile—Jeffrey Nash

Departments55 New Products58 Service Directories61 Classifieds63 Display Advertiser Index

ON THE COVER: A water treatment clarifierat the North Springs Improvement Districtin Coral Springs. (photo: Michael Gardner)

4 November 2014 • Florida Water Resources Journal

Jennifer Nyfennegger, Jess Brown,

Kara Scheitlin, and Chance Lauderdale

Biofiltration for drinking water applica-tions can offer many advantages with respectto operation and water quality. Biofilters arecommonly used for particulate removal (likeconventional granular media filters), but canalso simultaneously remove multiple organicand inorganic compounds. For example, inor-ganic constituents such as manganese and ironare commonly removed by biofiltration. Re-moval of organic compounds can decreasedissolved/biodegradable organic carbon (dis-infection byproduct precursors), color, taste-and-odor compounds, and trace organics,such as endocrine disruptors and pharmaceu-ticals. When filter media is not exposed tochlorine/chloramines, the microbiology natu-rally develops on the filter media. By relyingon this natural process to remove and, in thecase of organic compounds, destroy contami-nants, biofiltration offers a “green” technologywith low chemical and energy requirements.Even with these numerous benefits, drinkingwater biofilters can be prone to operationalchallenges. This article discusses these limita-tions and presents biofiltration control toolsfor preventing or overcoming them. Pilot re-sults from the optimization of these “Engi-neered Biofiltration” strategies are discussed,as well as opportunities for the holistic opti-mization of the water treatment process.

Potential Biofiltration Challenges

As water is treated through biofilters,biofilm growth and accumulation of solids re-strict flow and cause headloss across the filterbed. Biofilters are routinely taken off line forbackwashing to manage headloss buildup andmaintain uniform hydraulic flow. The biofilmis predominately comprised of extracellularpolymeric substances (EPS), which can occupya thousand times more void space than the mi-croorganisms (Mauclaire et al, 2004). The EPScan be both beneficial and detrimental withinthe biofilter. As listed in Table 1, benefits of mi-crobial EPS include adhesion and protectionfor the microorganisms; negative impacts in-clude clogging of biofilter media and under-drains. This can translate to operationalchallenges such as high headloss, decreased fil-ter productivity, and underdrain failure. Back-

washing alone is not always sufficient to re-move biological fouling, restore clean-bedheadloss, and prevent underdrain failures. Theaddition of chlorine and chloramines to thebiofilter is a common tool for biofilm control,but at the detriment of biological activity andassociated water quality performance.

Pilot studies spanning two Water Re-search Foundation projects focused on over-coming typical biofiltration challenges byimplementing two Engineered Biofiltrationstrategies: nutrient enhancement and hydro-gen peroxide (H2O2) supplementation.

Strategies to Overcome Biofiltration Challenges

Nutrient Enhancement - Effective biofil-tration for aerobic drinking water treatmentrequires a nutritional balance of oxygen, nu-trients, and biodegradable organic carbon.Under these conditions, microorganismsbreak down organic carbon into carbon diox-ide and water end products, the microbialpopulation grows, and microorganisms pro-duce EPS. Coagulation, flocculation, and sed-imentation processes upstream of biofilterstypically lead to nutrient-limited conditions inthe feed water. These limitations may stressbacteria, causing them to secrete large quanti-ties of EPS. This overproduction of EPS cannegatively impact hydraulic operation of thebiofilters, as discussed. Implementation of abalanced nutritional ratio reduces biologicalstress, thereby minimizing EPS productionand associated operational concerns.

Peroxide Supplementation - The H2O2, whenadded at low concentration, can oxidize and re-move EPS and inactive biomass. Peroxide addedto the biofilter feed water works to lower EPSconcentrations throughout the filter run. TheH2O2 applied at low doses does not harm activebiomass, and therefore allows the biofilter to con-tinue operating without degradation to water

quality. When underdrain clogging is a concern,H2O2 can be added to the backwash source.

Optimization of EngineeredBiofiltration Strategies

Materials and MethodsThe pilot study identifying the biofilter

enhancement strategies are described in Laud-erdale et al (2011). Follow-up studies wereconducted at Tampa Bay Water and DallasWater Utilities to optimize the EngineeredBiofiltration strategies (Lauderdale et al,2014). At each location, a pilot biofiltrationskid (Intuitech; Salt Lake City, Utah) includedfour dedicated influent feed pumps, fourbiofilter columns (6-in. diameter), peristalticpumps for feeding chemicals and spiking con-taminants, and a backwash system. Three ofthe four columns at both pilot sites werepacked with sand and granular activated car-bon (GAC), and the fourth with sand and an-thracite. Media heights were similar to the hostsite’s full-scale filters (6-in. sand and 48-in.media for Tampa Bay; 12-in. sand and 24-in.media for Dallas). Each filter was independ-ently operated with automatic flow controland configured for on-line or standby opera-tion. Hydraulic loading rates during testingranged from 2.5 to 4.0 gal per minute per sq ft(gpm/ft2). A break tank was used to store andprovide the backwash supply water. Pilot back-wash protocols (including air scour, high-rate,and low-rate backwash steps) were similar tothose for the host site’s full-scale filters.

Control and monitoring of the pilot skidwere provided through a skid-mounted pro-grammable logic controller. Headloss, filterflow, and effluent turbidity from each biofilterwere continuously monitored and loggedevery 10 minutes. In addition, water qualitysamples were collected two times per weekfrom the pilot influent and effluent of each

Holistic Look at Optimizing Biofilters and the

Water Treatment Process

Table 1. Positive and Negative Impacts of Biofilm Extracellular Polymeric Substances on Biofilter Operation

Continued on page 6


biofilter column. The samples were analyzedfor water quality parameters such as organiccarbon (dissolved and total), color, 2-methylisoborneol (MIB), geosmin, orthophos-phate, ammonia, manganese, and iron inaccordance with the appropriate methodsfrom the U.S. Environmental ProtectionAgency (EPA) or Standard Methods for the Ex-amination of Water and Wastewater.

Nutrient EnhancementLauderdale et al (2011) showed that low-

dose phosphorus supplementation (0.02 mg/L)to the biofilter feed water reduced headloss by15 percent over the course of a given filter run.This decrease in terminal headloss translates toan increase in the filter run time to reach agiven headloss trigger for backwashing. Thestudy also showed that nutrient enhancementincreased the removal of dissolved organic car-bon (DOC) across the biofilter. These studieswere conducted using settled water (pH = 7)from upstream ozonation and alum coagula-tion processes as the biofilter feed water.

Subsequent pilot studies showed thatbiofilters receiving settled water from up-stream processes using ferric as a coagulantdid not show hydraulic improvements withPO4-P supplementation alone. Water qualitymodeling suggested that dosed PO4-P ad-sorbed to ferric hydroxide carryover in thebiofilter feed at ambient pH. Increasing thefeed pH results in more dissolved (bioavail-able) phosphorus by changing the surfacecharge of the carryover floc to repel (thus in-hibiting adsorption of) the negatively chargedPO4-P molecules. When the biofilter feedwater pH was increased to between 8 and 8.5,hydraulic performance improved. Terminalheadloss of the nutrient- and pH-enhancedbiofilter decreased by >18 percent relative tothe control biofilter with no degradation in ef-fluent water quality. Thus, the type of up-stream coagulant and biofilter feed pH areimportant factors for successful implementa-tion of the nutrient-enhancement strategy.

Hydrogen Peroxide SupplementationPeroxide addition to the biofilter feed

water has resulted in improved hydraulic per-formance at pilots in Florida and Texas(Nyfennegger et al, 2013; Lauderdale et al,2011). The optimal dose was site specific, andvaried between 0.1 and 1 mg/L. This suggeststhat plant-by-plant optimization may be nec-essary to achieve an optimal use of this strat-egy.

A backwash study compared backwashefficacy using the backwash water with andwithout 10 mg/L of H2O2. Before each back-wash study, the underdrain fouling was pro-moted by adding 10 mg/L of ethanol to thebiofilter (6 in. above the underdrain) duringnormal filter operation. The measured pres-sure differential across the underdrain in-creased to approximately 10 times the baselinelevel prior to each underdrain fouling mitiga-tion test. Once this pressure differential wasachieved, backwashes were performed at 24-hour intervals without chemical mitigationuntil clean-bed underdrain differential pres-sures decreased and remained steady. Thisprocess (i.e., underdrain clogging followed bysuspension of ethanol dosing and manual ini-tiation of a backwash every 24 hours) was re-peated with 10 mg/L peroxide dosed to thebackwash water. Differential pressure meas-urements during the high-rate backwash stepwere 50 in. and 35 in. for the unenhancedbackwash and peroxide-enhanced backwash,respectively, indicating that the peroxide en-hancement helped to mitigate underdrainfouling. In addition, clean-bed underdrainpressures were slightly lower after the first en-hanced backwash (6.8 in.) versus unenhancedbackwash (7.7 in.). Differential pressure re-mained lower for the enhanced backwash pro-tocol during subsequent backwashes.

When implementing H2O2 supplementa-tion, the type of biofilter support mediashould be considered. Microbial activity of an-thracite biofilters decreased during periods ofperoxide addition (0.5 to 2 mg/L). However,microbial activity of the GAC biofilters was

steady before and during H2O2 testing, whichspanned the course of a year.

Upstream Coagulant DosePilot-scale-enhanced coagulation pre-

treatment optimization was performed con-currently with the biofiltration pilot at theDallas pilot site. Using coagulant doses of 60mg/L and 30 mg/L (as Fe2(SO4)3*9H2O), re-sults showed that the total DOC removalthrough the coagulation and biofiltrationprocesses was similar at the two doses tested.At the lower ferric dose, a higher percentage ofDOC was removed through biofiltration,which made up for the lower percent DOC re-moval observed across the coagulationprocess. This demonstrates synergy betweenthe coagulation and biofiltration processes,and presents a significant opportunity for costsavings on chemical costs without compro-mising water quality. At the host facility’s an-nual average design flow of 77 mil gal per day(mgd), the decrease in coagulant dose will re-sult in an annual savings of $961,000.

Media TypeAnthracite-based biofiltration perform-

ance for key water quality parameters (e.g.,DOC, geosmin) was inferior to performanceof GAC biofilters under control and enhancedconditions. However, site-specific goalsshould be considered when choosing betweenanthracite and GAC as a biofilter supportmedia. When the performance of anthracitebiofilters meets a site’s goals, the selection ofanthracite can result in significant cost sav-ings. Although more expensive, GAC may alsobe a more robust support media for biofiltersand offer more reliable performance duringprocess upsets.

Optimizing the Water Treatment Process

Optimized biofiltration may yield costsavings and water quality benefits across mul-tiple processes. These are illustrated in Figure1 and described here:1. Improved taste and odor removal (e.g.,

MIB, geosmin) may reduce ozone require-ments (if not otherwise needed to achievepathogen inactivation requirements).

2. Improved removal of organic compoundsmay reduce coagulant dosage requirementsto meet water quality goals for total organiccarbon (TOC ) and disinfection byproducts(DBP) precursor removal.

3. Reduced coagulant dosage may decreasesolids handling requirements.

4. Improved removal of organic compoundsmay reduce disinfectant (chlorine) demand.

5. Decreased underdrain fouling may extendthe life of existing underdrain infrastructure.Figure 1. Treatment optimization may yield cost savings

and water quality benefits across multiple processes.

Continued from page 4

Continued on page 8

6. Improved filter hydraulics will decreasebackwash return volumes and the associ-ated energy and chemical costs to dispose ofor retreat the return water.

Conclusion

Engineered Biofiltration strategies haveshown operational benefits at pilot sites inFlorida and Texas. Key conclusions include:� Effectiveness of the strategies can be im-

pacted by the type of coagulant used duringpretreatment, coagulant carryover, andbiofilter feed pH.

� The GAC may be a more robust supportmedia compared to anthracite, but an-thracite may offer cost advantages if per-formance objectives are met.

� Optimized biofiltration may yield cost sav-ings and water quality benefits across mul-tiple processes.

Acknowledgements

This work was made possible through thefinancial contributions of the Water ResearchFoundation, Tampa Bay Water, Dallas WaterUtilities, and the City of Arlington.

References

• Lauderdale, C., Brown, J., Chadik, P, Kirisits,M. 2011. Engineered Biofiltration for En-hanced Hydraulic and Water Treatment Per-formance. Water Research Foundation,Denver.

• Lauderdale, C., Scheitlin, K., Nyfennegger, J.,Upadhyaya, G., Brown, J., Raskin, L., Chiao,T., Pinto, A. 2014. Optimizing EngineeredBiofiltration. Water Research Foundation,Denver.

• Mauclaire, L., Schurmann, A., Thullner, M.,Gammeter S., and Zeyer, J., 2004. Sand fil-tration in a water treatment plant: biologicalparameters responsible for clogging. Journalof Water Supply: Research and TechnologyAQUA 53 (2) 93-108.

• Nyfennegger, J., Lauderdale, C., Brown, J.,Scheitlin, K. 2013. Engineered Biofiltrationfor Drinking Water Treatment: OptimizingStrategies to Enhance Performance. FloridaWater Resources Journal, 11, 12-17.

Jennifer Nyfennegger, Ph.D., P.E., is a sen-ior technologist with Carollo Engineers Inc. inSarasota; Jess Brown, Ph.D., P.E., is a vice presi-dent with Carollo Engineers Inc. in OrangeCounty, Calif., and is the director of the CarolloResearch Group; Kara Scheitlin, P.E., is technol-ogist with Carollo Engineers Inc. in Denver; andChance Lauderdale, Ph.D., P.E., is a vice presi-dent with HDR Engineering Inc. in Denver. ��




The City of Casselberry evaluated manyalternatives to comply with the Stage 2Disinfectants and Disinfection Byprod-

ucts (D/DBP) Rule compliance regulatorychanges and selected implementation of gran-ular activated carbon (GAC) filtration at itsSouth Water Treatment Plant (WTP). TheCity performed preliminary planning onmany different precursor removal and treat-ment methods, including ozonation, ultravio-

let radiation, GAC filtration, and changing dis-infection methods to chloramination. Follow-ing preliminary selection of GAC, pilot testingwas performed to evaluate precursor removaleffectiveness.

Reiss Engineering Inc. designed the GACimprovements and continued its servicesthroughout construction as part of the imple-mentation team. Wharton-Smith Inc. was se-lected as a construction manager at-risk(CMAR) contractor to perform the requiredGAC treatment process improvements at theWTP. The CMAR process provided a reducedconstruction schedule and allowed the Cityand engineer to maintain a nonadversarial re-lationship with the contractor, essentially al-lowing all parties to act as a construction team.The team worked together to reduce time onshop drawing submittals, request for informa-tion (RFI) reviews, and field changes, and ac-tively pursued value engineering optionsthroughout construction of the required im-provements. The team also added to the scopeof the initial project to greatly improve it,while reducing the construction schedule andkeeping the project within budget.

Steps to Compliance

The City is in the process of upgrading itsfinished water treatment process at the WTPin order to comply with EPA’s Stage 2 D/DBPRule. The EPA adopted the Stage 2 D/DBPRule in 2006 and started working with potablewater providers for completion of the InitialDistribution System Evaluation (IDSE) toevaluate the drinking water sampling plansimplemented by those providers (Figure 1.) Amajor change between the Stage 1 D/DBP Ruleand the Stage 2 D/DBP Rule is the implemen-tation of the Locational Running Annual Av-erage (LRAA) method of reporting samples.Previously, utility providers averaged the DBPconcentrations from samples taken through-out the entire distribution system. The LRAAmethod tracks DBP results of specific sam-pling sites and requires reporting on every spe-cific site. The City anticipated that it would be

Construction Manager At-Risk Implementationfor a Water Treatment Plant Granular

Activated Carbon Filtration ProjectEdward Alan Ambler, E. Devan Henderson, and Matt Peterson

Edward Alan Ambler, P.E., LEED AP, iswater resources manager with the City ofCasselberry; E. Devan Henderson, P.E., is aproject manager with Reiss EngineeringInc. in Winter Springs; and Matt Peterson isa project manager with Wharton-SmithInc. in Sanford.

F W R J

Figure 1. Casselberry Initial Distribution System Evaluation Sampling Plan


in noncompliance with the Stage 2 D/DBPRule based on implementation of the LRAAmethod for the WTP. The City started prelim-inary planning for treatment alternatives andselected utilization of GAC filtration to re-move the DBP precursors within the sourcewater to ensure compliance with the Stage 2D/DBP Rule.

Unfortunately, the City was unable toconstruct the required capital improvementproject prior to implementation of the Stage 2D/DBP Rule and encountered its first Maxi-mum Contaminant Level (MCL) exceedancein late fall of 2013.The City proceeded with thedesign of the required improvements, and de-sign and permitting were completed in thewinter of 2013.

The City worked closely with the FloridaDepartment of Environmental Protection(FDEP) to detail the process the City wouldfollow to correct the MCL exceedances. TheFDEP evaluated the information provided bythe City and determined it was taking proac-tive measures to correct the MCL exceedance.The FDEP issued the City a compliance assis-tance offer instead of a consent order to makethe necessary improvements. A compliance as-sistance offer is a letter presenting an actionplan required to correct the regulatory viola-tions. A consent order is a court-approved casedictating the terms of an agreement betweena city and FDEP that could be enforced.

City and System Background

Casselberry is a medium-sized commu-nity in urban Orlando that provides potablewater to approximately 55,000 customers. TheCity owns and operates three water treatment

plants that treat and distribute potable waterto its customers. The WTP currently suppliesdrinking water to meet an average annual de-mand (ADD) of 1.7 mil gal per day (mgd) anda maximum day demand (MDD) of 2.5 mgd.The existing WTP includes three groundwaterwells, forced draft aeration, storage, and high-service pumps. The City currently disinfectsthe groundwater using sodium hypochloriteand adds orthopolyphosphate as a corrosioncontrol inhibitor (Ambler et al, 2013).

The groundwater from the wells at theWTP contains higher levels of hydrogen sul-fide and organic content than the groundwa-ter used as source water at the other twoCasselberry WTPs. The forced draft aerators(Figure 2) at the WTP are used to reduce thelevels of hydrogen sulfide in the finishedwater.

Historically, the City observed higher lev-els of trihalomethane (THM) and haloaceticacids (HAA) levels in the southern portion ofthe City’s distribution system. Multiple sam-pling events from the GAC pilot study at theWTP indicate the average source water totalorganic carbon (TOC) is 1.7 mg/L, pH is 7.7,and the ultraviolet measure (UV-254) is 0.04cm-1 (Ambler et al, 2013). It was anticipatedthat at these TOC levels, the City would be inviolation of the Stage 2 D/DBP requirements,based on experience with other utilities in thevicinity. The City evaluated several options atthe planning level to minimize the DBP for-mation, including the following:� Inspection and remediation of the potable

water wells� Use of chloramines, ozone, or ultraviolet ir-

radiation for disinfection instead of freechlorine

� Unidirectional flushing to remove any de-bris or other material within the distribu-tion system that would reduce theeffectiveness of disinfection

� Autoflushers aimed at purging old waterfrom the distribution system

� GAC filtration to remove the organics fromthe source water (Ambler et al, 2014)

Many of the lower-cost options, such asoperational changes, well remediation, and uni-directional flushing were completed, but littlechange in DBP formation was observed. TheCity anticipated this result and proceeded withconducting a pilot study for GAC at the WTP.

Granular Activated Carbon Pilot Study and Design

During initial phases of the project, no fa-cilities were operating at full scale with GACtreatment in the central Florida area to assessthe efficiency of GAC to remove TOC from thegroundwater; therefore, a pilot study was con-ducted at the WTP to define GAC design pa-rameters. Over the course of three months,aerated well water was fed into two types (Cal-gon and Norit) of GAC-filled columns tomonitor TOC and UV-254 (a surrogate ofTOC) breakthroughs and determine the car-bon regeneration rates. Treated water wastested for chlorination DBPs and various waterquality parameters. The DBP formation po-tential was evaluated by dosing chlorine to theGAC effluent water, and to blends of GAC ef-fluent with source water, to obtain representa-tive DBP formation, rather than performing atheoretical extrapolation between source wa-

Figure 2. Forced Draft Aerators Figure 3. Trihalomethane Formation in Granular Activated Carbon-Treated Water

Continued on page 12


ters and blended streams. The chlorine doseapplied was sufficient to provide chlorineresidual from 0.4 to 1.8 mg/L after three daysof contact time. Dose and contact time wereselected to represent system operations anddistribution system conditions.

In general, results from the pilot study in-dicated that water treated with Calgon GACmedia had lower THM and HAA (Figure 3).The THM concentrations for the Calgonmedia were about 55 µg/L after three days andabout 60 µg/L for HAA. For the Norit GACmedia, the THM concentration after threedays was approximately 65 µg/L and about 70µg/L for HAA.

Based on the pilot study results, the fol-lowing design criteria were developed for thedesign phase of the GAC system: � Four 12-ft-diameter GAC vessels � 40,000 lbs of carbon per GAC vessel� Minimum empty bed contact time (EBCT)

of 17 minutes at MDD

During the design phase of the project,multiple adjustments were made based onproject team discussions to improve the oper-ations at the WTP; these included GAC vesselincorporation into the process flow, bypassoptions, and an additional GAC vessel. The in-corporation of the GAC vessels was selectedfollowing the aerators to prevent sulfide in thewater from absorbing to the carbon and de-creasing its TOC removal effectiveness. Theexisting clearwell was utilized and the pumpstation was upgraded to accommodate thechange in head conditions required to pumpthe water from the clearwell through the GACvessels into the ground storage tanks. This op-tion was cheaper in cost compared to con-struction of a second pump station andallowed for less maintenance of equipment.The option was also simpler in terms of in-strumentation and controls.

Although the pilot testing indicated thattreatment of full flow is necessary to achievethe desired reduction in DBPs, a bypass option

was included to aid operations with cost opti-mization in the event that the full-scale oper-ations performed better than initial pilottesting. An additional GAC vessel was addedto allow for increased flexibility and reliability.Five GAC vessels and the bypass allowed forthe operations staff to run all WTP wells si-multaneously, as well as decrease the numberof deliveries required. Although not a require-ment, decreased deliveries is an additionalbenefit for this facility since the WTP is locatedin a residential area.

Regulatory Summary and Severityof Risk Associated with Maximum

Contaminant Level Exceedances

In fall of 2013, while the design phase ofthe WTP improvements was ongoing, the Cityreceived its first quarterly sampling MCL ex-ceedance associated with the implementationof the Stage 2 D/DBP Rule. Several samplingsites within the City’s distribution system ex-ceeded the MCL limits for THMs. These sam-pling sites were previously averaged in with theremaining sampling sites, which had lowerTHM concentrations and reduced the overallTHM average concentration for the entire dis-tribution system. The sampling sites were nowin violation because of implementing theLRAA change in the Stage 2 D/DBP Rule. Thesampling sites were geographically focusedwithin the influence zone of the WTP withinthe distribution system. The City reported theMCL exceedance to FDEP and both workedclosely to determine the appropriate notifica-tion procedure.

The City was required to send a one-pagemailer (Figure 4) to all customers within itsexisting distribution system and place an ad-vertisement in the local newspaper concern-ing the MCL exceedance. The notificationcontained one full page of complex languageas specified by the U.S. Environmental Protec-tion Agency (EPA) and FDEP and a contactnumber for the City for any questions. Thisnotification was delivered to the City’s cus-tomer base in January 2014 and the City re-ceived well over 100 inquiries concerning thefirst notification. At the time, the City antici-pated having to mail the notification everyquarter until its GAC project was completedat the WTP, which was in December 2014.This timeline encouraged City staff to researchadditional information concerning MCL ex-ceedances to include frequently-asked ques-tions on its website and direct conversationswith customers who had concerns over thepublic notification.

Specific language within the public notifi-cation that appeared to bring the most concernFigure 4. Maximum Contaminant Level Exceedance Notification


to the City’s customers is “Some people whodrink water containing trihalomethanes in ex-cess of the Maximum Contaminant Level overmany years may experience problems with theirliver, kidneys, or central nervous system andmay have an increased risk of getting cancer.”This language is harsh and it is understandablehow the City’s customer base could have reser-vations concerning drinking the City’s water.City staff researched the basis on which this de-termination was made to prepare City staff toanswer the questions of its customers.

During development of the Stage 2D/DBP Rule, EPA determined the increasedrisk of developing cancer based on a referencedose (RfD) and health advisory (HA) limit.The RfD is a daily exposure level that is be-lieved to be without appreciable health risk tohumans over a lifetime. This RfD correlates toa 70-kilograms (kg) adult who consumes 2litres of water per day over a 70-year lifetime.The HA limit for THMs and HAA is based onan upper-bound excess lifetime risk of 1 in 1million. So, if customers consume a little morethan a half-gal of City water over a 70-year pe-riod, they are 1 in 1 million times more likelyto get cancer (EPA, 2007).

In January 2004, the American WaterWorks Association (AWWA) issued a 126-pageletter (Figure 5) to EPA officially respondingto the proposed rule making for Stage 2D/DBPs. The Association commended EPA forall of its work developing the Stage 2 D/DBPRule (done in conjunction with AWWA), butoffered three main defects to the proposal:� The definition of significant excursions and

the resulting actions required of utilities areinappropriate. The AWWA defines signifi-cant excursions as individual high THM orHAA compliance sample values that placea water provider close to or into noncom-pliance with either the Stage 2 D/DBPTHM or HAA5 MCLs.

� The bias in the presentation of health-ef-fects data is so pervasive that it calls intoquestion EPA’s obligation and commitmentin the agreement in principle to issue a reg-ulation that complies with applicable lawand regulation.

� The quantification of health effects thatmay or may not be realized through thenew MCLs is inappropriate, particularly inareas where the agency specifically con-cluded that quantification was not possiblein “illustrative examples” (AWWA, 2004).

The low risk (1 in 1 million) of develop-ing cancer (EPA, 2007) from the City’s potablewater that exceeded the MCLs for THM andHAA, coupled with AWWA’s comments on theStage 2 D/DBP Rule development, did not ap-

pear to make answering customers complaintsor comments any easier for City staff. How-ever, the City was still in violation of the MCLlimits as imposed by the Stage 2 D/DBP Ruleand began extensive communication withFDEP on how to correct the MCL exceedance.

Compliance Assistance Offer With Florida Department of

Environmental Protection

The FDEP had several options availableto ensure that the City would take correctiveaction to address the MCL exceedance andbring its potable water into compliance withregulations. Compliance assistance is one ofthe four tools available that EPA and FDEP usefor promoting or addressing compliance withregulations. Compliance assistance primarilyincludes activities, tools, or technical assistanceto help the regulated community meet its reg-ulatory obligations. Another method, compli-ance monitoring, involves on-site visits byqualified inspectors and review of requiredagency submittals. Compliance incentives area set of policies and programs that eliminate,reduce, or waive penalties for businesses, in-dustry, and government agencies that volun-tarily discover, promptly correct, and/orprevent future environmental violations. An-other tool is enforcement actions, which aredefined as civil enforcements that protecthuman health and the environment by takinglegal action to bring polluters into compliancewith the law. An administrative order can beissued with or without penalties that directs anindividual, business, or other entity to take ac-tion to come into compliance or to clean up asite (http://www.epa.gov).

City staff requested a meeting with stafffrom FDEP to discuss the MCL exceedance vi-olation and the City’s plans to correct the de-ficiency. City staff subsequently explained inextensive detail the preliminary planning ef-

forts, pilot study, design for GAC improve-ments, and preliminary efforts the City hadmade to construct the improvements via theCMAR method. The City had received a con-struction permit for the project approximatelya week prior to meeting with FDEP about theMCL exceedance. The FDEP acknowledgedthat the City had been making significant ef-fort to correct the MCL exceedance; however,the City was unable to construct the requiredimprovements prior to the implementation ofthe new regulations

The FDEP elected to offer a complianceassistance offer instead of an alternative en-forcement action, such as a consent order. Thecompliance assistance offer still maintained theminimum regulatory actions required, such ascontinued quarterly sampling and public noti-fication in the event of MCL exceedance. Ad-ditional information, such as continuedmonthly updates on the status of constructionof the GAC project at the WTP and voluntaryinspections, were required within the compli-ance assistance offer. Complying with these re-quirements and maintaining the establishedproject schedule without further MCL ex-ceedance once the GAC treatment upgrades areplaced into service will allow the issue to be re-solved without enforcement. The FDEP un-derstood that the City was progressing towardsresolving the problem and it wanted to workwith the City without involving burdensomeenforcement procedures.

Construction ManagementAt-Risk Method Benefits

As design documents were finalized,Wharton-Smith was contacted for precon-struction services for construction of theGAC treatment system at the WTP. With theCity being up against the compliance dead-line set forth by the compliance assistance


Figure 5. AWWA Letter to EPA on Stage 2 D/DBP Rule Promulgation



offer, the CMAR delivery method was thebest-suited contract delivery method for thisproject. Benefits in using the CMAR deliverymethod for the GAC treatment addition atthe WTP include:� Selection of contractor and subcontractors

based on qualifications � Preconstruction services� Expedited schedule� Construction manager minimizing change

orders by establishment of an owner con-tingency within the guaranteed maximumprice (GMP)

� Transparency of cost control

Selection of a Construction Manager At-Risk Contractor

The CMAR delivery method is the bestcontract delivery method to fast-track a proj-ect while maintaining a high quality level. Thisproject built upon the previous success that allof the represented firms had established. Keystaff members on each team were identifiedthat performed together well on previous proj-ects and that were assembled for this project.Several meetings were held early in the processto establish goals, objectives, and a clear pathfor project success.

Preconstruction Services and Value Engineering

Preconstruction involvement of the con-struction manager (CM) adds value by inject-ing the builder’s insight into the project priorto the establishment of the GMP. It is in theowner’s interest to select a construction man-ager early in the design phase so that CM pre-construction services provide the best value tothe project (Kaplin and Conley, 2009). In thebeginning phases of the GMP establishmentfor the project, it was apparent that this proj-ect would be over budget for previous fundsallotted by the City. A thorough review of thecontract documents was done, which gener-ated questions to avoid scope gaps, add value-minded changes, and address potentialconflicts in the contract drawings. As theCMAR, Wharton-Smith was responsible forcreating bid packages for subcontractors andvendors and providing bidding services to theCity for the project. The questions and an-swers generated in preconstruction reviewmay have minimized the value engineering(VE) offered after establishment of the GMP,but they allowed for competitive bid pricingon value-minded changes and scope gaps dur-ing the question-and-answer process, whichreduced the overall cost of the project. Con-

siderable effort was made during design of theproject to minimize construction costs, so itwas not surprising that there was not muchopportunity for additional VE on the project.At the early stages, it was essential to award theproject and start construction as soon as pos-sible to meet the pressing schedule require-ments.

Cost Control, Transparency, and Owner Contingency

In a CMAR delivery method, the CM iscompensated for actual costs incurred, generalconditions, and the CMAR fee. General con-ditions are defined as support costs duringconstruction, such as field trailers, utilityusage, materials testing, survey, security,dumpsters, and similar auxiliary costs requiredto complete the project (Kaplin and Conley,2009). Invoices and backup documents for allcosts are submitted with the monthly pay req-uisition as a transparent “open book” ac-counting relationship with the owner; thisprovides assurance that all involved parties arebeing good stewards of the rate payers’ money.Being good stewards was defined as a primaryobjective early on in initial project meetingsand has been clearly adhered to throughoutdesign and construction of the project.

Included in the GMP, the City providedfor a contingency which can only be usedupon mutual agreement among the involvedparties. The purpose of this contingency is toprotect the City from unforeseen conditions,scope gaps, and/or design errors and omis-sions that would typically result in contractchange orders. One of the many successes ofthe project is that the contingency has re-mained protected throughout construction.After construction progressed far enoughalong, with the contingency remaining un-spent, a portion of it was refunded to the Cityto fund alternative projects outside of thescope of the WTP project.

Conclusion

The City of Casselberry performed ex-tensive preliminary planning work and pilot-tested the effectiveness of GAC in conjunctionwith existing forced draft aeratoration at theWTP, the only treatment plant in Casselberry’ssystem that supplied potable water that did notmeet the Stage 2 D/DBP Rule. The GACproved to be an effective treatment method forthe removal of organic matter, which con-tributed to THM and HAA formation levelsthat exceeded the MCLs under the revised reg-ulations. Significant capital improvement andoperating costs are associated with design and

construction of GAC improvements to treatthe source water at the WTP.

The City worked closely with FDEP to il-lustrate all of the efforts the City completed inan attempt to meet the Stage 2 D/DBP regula-tions. The FDEP offered an alternative to en-forcement action with a compliance assistanceoffer since the City had a defined correctionplan. The City was required to provide con-tinued notifications to its entire customer basefor every failed LRAA each quarter, which iscostly and requires significant interaction withthe customers. City staff performed extensiveresearch on the adverse health effects of MCLexceedance and was partially able to conveythis message to its customer base. It would behelpful if EPA could provide additional guid-ance to clarify these adverse health effects, asrequested by AWWA.

The CMAR project delivery method wasselected as the best method to meet the ag-gressive schedule and ensure quality deliveryof construction of the improvements. Estab-lishing a clear goal of being good stewards forthe rate payers at the beginning of the projectwas successful in encouraging the team tomake continual strides to meet the goal. TheCity has maintained a successful projectschedule and is anticipating completing theWTP project in December 2014.

Compliance with the Stage 2 D/DBP reg-ulations could potentially have a further-reaching effect on utility providers than EPAmay have initially predicted, specifically due tothe changes with implementing LRAAs.

References

• Edward Alan Ambler, Greg Goodale, DawnSwailes, Steve Black, Edward Talton, GlennDunkelberger, Ferdinand Vasquez, 2013.“Granular Activated Carbon for Stage 2D/DBP Rule Compliance, City of Casselberry.”

• Edward Alan Ambler, E. Devan Henderson,Glenn Dunkelberger, 2014. “Stage 2 D/DBPRule: Granular Activated Carbon FollowingForced Draft Aeration.”

• Kaplin, John, and James Conley. "Construc-tion Management at-Risk as a DeliveryMethod for Water Projects." New EnglandWater Works Association, 2009 Annual Con-ference (2009): 4.

• American Water Works Association, Jan. 16,2004. “Stage 2 Disinfectants and DisinfectionByproducts Rule: National Primary and Sec-ondary Drinking Water Regulations: Ap-proval of Analytical Methods for ChemicalContaminants, Proposed Rule, 68 FederalRegister 49547, OW-2002-0043.”

• EPA, 2007. “Drinking Water Standards andHealth Advisories Table.” USEPA, Region 9.��








Scott Ruland, water and wastewatermanager, City of Deltona, provided thesequestions and answers. Thank you, Scott, forproviding such great water operatorinformation.

1. What is the major factor affecting theefficiency of the aeration process in awater plant?

a. Concentration of volatile organiccompounds (VOCs)

b. Iron levelsc. Surface contact between air and water d. Flow rates

2. Algal blooms may create several problemssuch as tastes and odors, depletion ofoxygen in the source water, and additionalorganic loadings. What is anotherproblem associated with algal blooms?

a. Increased pHb. Decreased diatomsc. Reduced trihalomethane (THM)

formationsd. Aerobic conditions

3. One primary purpose of the inlet zoneof a sedimentation basin is to distributethe water evenly into the sedimentationbasin. What is the other purpose of theinlet zone?

a. Provide additional mixing throughbaffles

b. Control water velocity as it entersthe basin

c. Provide an area for visual inspectiond. Provide a sampling location to

confirm coagulant dosages

4. What test can be performed that willgive an operator a quick indication ofthe performance of the sedimentationprocess?

a. Turbidity into and out of the tankb. Conductivity into and out of the tankc. Coliform sampling at the tank outletd. Dissolved oxygen content to verify

there is no anaerobic conditions“septic sludge”

5. Which process is used to rapidly mixand disperse a coagulant chemical withraw water?

a. Hydraulic mixingb. Mechanical mixingc. Diffuser mixingd. Flash mix

6. What is the optimum pH range forcoagulation?

a. 5 to 7 b. 6 to 7c. 7 to 8 d. Greater than 8

7. What type of corrosion occurs whentwo dissimilar metals are joinedtogether?

a. Stray current corrosionb. Galvanic corrosion c. Immersion corrosiond. Dielectric corrosion

8. What is not one advantage of usingchloramines as a disinfectant?

a. Reduces the formation of THMsb. Penetrates the biofilm on pipe walls

to kill microorganismsc. Reduces tastes and odorsd. They are a stronger disinfectant

than chlorine

9. What undesirable condition can occurfrom opening and closing a valve toquickly?

a. Water hammerb. Tuberculationc. Backsiphonaged. Backflow

10. What type of filter media is used toremove tastes and odors?

a. Granular activated carbonb. Clay brickc. Garnetd. Alum

Answers on page 56

Readers are welcome to submitquestions or exercises on water or wastewater treatment plantoperations for publication inCertification Boulevard. Send your question (with the answer) or your exercise (with the solution) by email [email protected], or by mail to:

Roy PelletierWastewater Project Consultant

City of Orlando Public Works DepartmentEnvironmental Services

Wastewater Division5100 L.B. McLeod Road

Orlando, FL 32811407-716-2971

Certification Boulevard

Roy Pelletier

SEND US YOURQUEST IONS

Test Your Knowledge ofWater Treatment Topics

Check the ArchivesAre you new to the water and

wastewater field? Want to boost yourknowledge about topics youʼll faceeach day as a water/wastewater pro-fessional?

All past editions of CertificationBoulevard through the year 2000 areavailable on the Florida Water Envi-ronment Associationʼs website atwww.fwea.org. Click the “Site Map”button on the home page, then scrolldown to the Certification BoulevardArchives, located below the Opera-tions Research Committee.

LOOKING FORANSWERS?


How many of you reading this aremembers of AWWA and not activelyparticipating in the organization? I’d

suspect quite a few. Don’t worry; I’m not goingto put a guilt trip on you. Quite the contrary—I’m going to offer a solution.

Has anyone asked you to become moreactive? Has an opportunity for you to dosomething really good with other Florida Sec-tion members come to your attention that youjust would not want to miss, but you missed itanyway? I suspect unless you have commit-ments that are more pressing in your life, theanswer would be “No.”

Membership in the association is thebest way to learn more about all facets of thewater industry, network with your peers, andestablish lifelong friendships with some greatpeople. It’s not happening for everyone in theassociation, and you may be one of them.

The new AWWA mentoring programhas the potential for changing that for manynew members. The program matches newmembers with existing members, and to date,there are 20 pairings in the section. Thatmeans that 20 new members have someonespecial in our association to talk with, intro-duce them to other members, and assist themin matching their interests to section effortson committees and/or councils.

For those of you who would like to par-ticipate, the link to the application form ison the www.fsawwa.org home page. CaseyCumiskey, the FSAWWA training coordina-tor/membership specialist, is our staff men-toring program contact and expertextraordinaire! She can be reached [email protected] or (407) 957-8447.

The section has over 100 committeeswith many different topics including re-search, backflow protection, legislative, regu-

latory policy, Water For People, water towercompetition, membership, mentoring, cus-tomer service, treatment plant and operatorsawards (where I started!), fall conference,Likins scholarship, information technology,and finance, to name a few.

Each section committee has a chair, andpreferably, but not always, a vice-chair. Theposition of vice-chair is an excellent oppor-tunity to hone leadership skills while work-ing under the tutelage of the chair.

You might be thinking, “I’m new at work,I just got married, I’m active in my church,and/or my first child just arrived—how muchtime is any of this AWWA stuff going to takeanyway?” These are all important considera-tions when deciding whether or not to becomemore active.

My section activities were done prima-rily at work. My supervisor, Bill Stephenson,was an active AWWA member. He was theprevious Treatment Plant and OperatorsAwards Committee chair and later becamethe section chair. Not all supervisors are thatactive in AWWA, but if they have experiencein the water industry, they should know thecritical role AWWA plays in making drinkingwater in America the most excellent in theworld. Ask your supervisor if you could setaside some time for FSAWWA activities.

When I attended an AWWA annual con-ference (ACE), my wife, Janis, and daughtersaccompanied me. My oldest daughter, Jessica,had her first flight to the Dallas ACE whenshe was 8 months old. She and her sister, Joye,have wonderful memories of exploring theexhibition halls over the years. Sightseeing inour nation’s capital was one of many activi-ties my family experienced, which we’ve alsodone in the other major cities that havehosted this convention.

Your active participation in the sectioncan increase your knowledge of the industryand grow connections to experienced peersthat will benefit your employer in countlessways. Personally, you will cherish the lifelongfriendships developed through the associa-tion. I know—I have them!

You may have heard this phrase and be

recognizing it in your career: The more youknow, the more you know you don’t know. Atwist on that phrase is that the more youknow, the more you know you could know.In other words, the more you realize what’sbeing done, the more you realize what couldbe done. That’s the phrase I’d like to see uscultivate.

The section is involved with many water-related projects and issues. A less active mem-ber might just need to find out the one thatinterests him or her and get connected. Butwhat if there’s something that interests some-one that isn’t being addressed right now? Isthere a method in place to find it and make ithappen? Not yet, exactly, but I’d like to intro-duce you to a new initiative.

I’d like to see us solicit ideas of all kindsto improve any and all aspects of the waterindustry. Whether or not the originator iswilling and/or able to work on the idea does-n’t matter. Either way, it should be placed ina depository for future consideration andpossible action. I’d love to see a treasure troveof ideas that anyone in our section can con-tribute to and look through to find some-thing that fits their skills and interests thatthey can then adopt and work on. In order tomake this happen we might need anothercommittee—a New Water Idea Discovery,Development, Assignment, and Implementa-tion Committee!

You may be a dreamer and can imaginenew ideas that would be excellent for us to ex-plore. You may be a doer who just needs anidea to spark your creativity. You may take thelead or you might work under a great leaderwho can show you how it’s done.

Take the initiative today—right now—to start taking full advantage of your mem-bership in AWWA. Connect. Contribute.Enjoy the lifelong journey.

I also hope to see you at the section’s fallconference, being held November 30 throughDecember 4, where lots of new ideas will be gen-erated and discussed. The Young ProfessionalsCommittee is having a joint luncheon with thementoring program mentors and mentees onTuesday at the event. Don’t miss it! ��

Carl R. Larrabee Jr.Chair, FSAWWA

Mentoring Program Increases Section Participation

and Sparks Creativity

FSAWWA SPEAKING OUT


Roger K. Noack

Generally, when one hears the word “biofil-tration” the first thing that comes to mind is a trick-ling filter in a wastewater treatment plant—smelly,yucky, and big! However, biofiltration is becomingan accepted drinking water treatment process forthe removal of many contaminants found intoday’s source water supplies. Biofiltration can beas simple as a conventional media filter operatedwithout chlorine residual, or it can be combinedwith an advanced oxidation process (AOP), suchas ozone. Drinking water biofiltration has becomecommonplace, with over 15 bil gal per day of in-stalled capacity in water treatment facilities acrossthe United States. These facilities can achieve filterloading rates from 2 to 10 gpm/ft2 and higher, usingdesign and operational parameters similar to con-ventional filters. Indeed, biofiltration is no longer adirty word for drinking water treatment.

To understand how biofiltration can be ef-fective in treating source water, it is important tounderstand biofiltration basics. Similar to a trick-ling filter, a media substrate or support structure,such as sand, anthracite, or granular activated car-bon, is required. The media provide a place fornaturally occurring bacteria to attach and grow ina matrix known as “biofilm.” Biofilm is composedof microbial cells, their metabolic byproducts, andfiltered particles. In a biofilter, water treatment isachieved through microbial activity, biofilm andmedia surface chemistries, and basic filtration. Fil-ter influent flows over the biofilm, where absorp-tion and diffusion allow bacteria to capture andmetabolize natural organic matter, metals, or traceorganic contaminants (e.g., pharmaceuticals, pes-ticides, tastes and odors, etc.). Simply put, biofil-tration employs bacteria to “eat” the undesirablecontaminants, changing them to innocuousbyproducts or removing them entirely.

Biologically Active Filtration

What stimulates microbial growth in abiofilter? The list includes organic and inor-ganic substrates naturally found in source water,as well as those created by treatment processes,such as chlorination or ozonation.

Raw water contaminants are somewhatsource dependent. For instance, nitrates and per-chlorates are generally found only in groundwatersources. Taste- and odor-causing compounds,geosmin, and 2-methylisoborneol (MIB) produced

by blue-green algae, are found only in surface wa-ters or groundwater under the influence of surfacewater. Each source, and how biofiltration will treatthe problematic constituent, will be explored.

Source aquifer characteristics dictate whatone can reasonably expect to find in the ground-water supply. For instance, rainwater passingthrough aquifer recharge areas containing natu-ral organic matter lenses can exhibit high am-monia concentrations.

Here are just a few of the typical primary con-stituents that can be removed with biofiltration:• Iron • Ammonia• Manganese • Nitrate• Hexavalent chromium • Perchlorate• Volatile organic carbon

Surface water sources are generally morecomplex than groundwater because of various ter-restrial influences that can affect water quality.When a densely forested wetland experiences adrought, existing ponds and retained water evap-orate, concentrating nutrients and organic matteracross the watershed. When the rains come, thenutrient- and organic-laden water is carried to apotential surface water supply, leading to increasedcolor and total organic carbon levels, and possiblyblue-green algal blooms. In addition, certain sur-face water treatment processes will alter the avail-able dissolved constituents, creating undesirablecompounds. For instance, using free chlorine fordisinfection will change some dissolved organicsinto regulated disinfection byproducts (DBPs)with public health implications. This means thatthe location of the biofilters is somewhat depend-ent on what the raw water constituents are and thetreatment processes utilized.

Installing biofilters at the head of a surfacewater treatment plant is a relatively new twist.However, when one considers some of the con-taminants that need to be removed earlier ratherthan later, it makes a lot of sense. Surface sourcesare prone to algal blooms when the water is hotand nutrients are high. With the algae blooms, twotroublesome contaminants that do not affect reg-ulatory quality but have a huge aesthetic impactare geosmin and MIB. The generally acceptedmethod for removing these constituents is ad-sorbing them into powdered activated carbon(PAC). Using PAC is costly and not always effec-tive because not enough PAC is added or there isnot enough contact time for the compounds to beadsorbed onto the carbon particles. With biofil-

tration, extremely high concentrations of geosminand MIB (in the ppm range versus the 3 to 5 ng/lthreshold level) can easily be removed. In additionto geosmin and MIB, biodegradable organic mat-ter that can lead to high DBP levels should be re-moved earlier rather than later, and certainly priorto application of a disinfectant. If the source is sub-ject to conditions that contribute to high levels ofthese types of contaminants, or others, such as en-docrine disruptors and pharmaceutically activecompounds, then placing biofiltration at the headof the plant should be considered, if possible.

Typically, biofiltration is the final treatmentprocess. It “polishes” finished water by removingconstituents and assimilable organic carbon(AOC) created by ozonation, which may causeregulatory problems or affect distribution waterquality. It also functions as a granular media fil-ter to provide final turbidity removal, as well asa physical barrier to pathogens.

Ozone is a powerful oxidant used to destroytaste and odor compounds or disinfectant-resis-tant protozoans, such as Cryptosporidium oocysts.Because ozone is so powerful, when it is injectedinto the water, it oxidizes complex natural organicmacromolecules and converts the organic matterinto smaller, more readily degradable organiccompounds known as AOC. If not removedthrough biofiltration, AOC can lead to distribu-tion water quality problems, including bacterialregrowth, corrosion, and reduced disinfectantresidual. Fortunately, AOC can be removed withbiofiltration, because the microorganisms popu-lating the filter love eating the bite-size organicsthat remain after ozonation.

Another benefit of biofiltration is reducingtreated water total organic carbon (TOC) levels.The TOC reacts with disinfectants to form regu-lated DBPs, such as trihalomethanes and haloaceticacids, as well as unregulated DBPs. Reducing TOCbefore free chlorine disinfection reduces DBPs, pro-viding numerous public health benefits. Biofiltra-tion can also be effective at biodegrading haloaceticacids that form prior to biofiltration.

Using the correct treatment methods, biofil-tration does not have to be the smelly and yuckyprocess many have traditionally associated withit. Instead, it can provide cost-effective treatmentof metals, organics, taste and odor compounds,and contaminants of emerging concern.

Roger K. Noack, P.E., is east region desalina-tion leader at HDR Engineering Inc. in Tampa. ��

Biofiltration: No Longer a Dirty Word for Drinking Water Treatment

T E C H N O L O G Y S P O T L I G H T

Technology Spotlight is a paid feature sponsored by the advertisement on the facing page. The Journal and its publisher do not endorse any product that appears in this column. If you would like to have your technology featured, contact Mike Delaney at 352-241-6006 or at [email protected].


The Orlando Utilities Commission (OUC)is performing an upgrade and replace-ment program for the ozone treatment

systems at all seven OUC water treatment plants(WTPs). The plants utilize liquid oxygen (LOX)as the feed gas for the ozone generation equip-ment. In order to standardize equipment and in-crease ozone generation and dissolutionefficiencies, OUC and CDM Smith are perform-ing a design and implementation plan for thetreatment system upgrades at each of the WTPs.

The purpose of this testing is to outline theprocedure and interpret the results from the full-scale ozone system testing at three of OUC'splants and the effects on the sizing of the ozonegeneration and dissolution systems. The goalsfrom this testing effort are to:� Determine the base ozone demand for hydro-

gen sulfide (H2S) oxidation.� Measure and trend the ozone decay rate in the

raw water at various ozone-applied doses.� Ascertain possible effects and correlations of

the ozone-applied dose to the disinfectionbyproduct (DBP) formation potential of theraw water.

� Establish ozone-to-sulfide dose ratio that willbe applied to each facility for the design of thesystem improvements.

The three facilities used for the testing arethe Conway, Navy, and Pine Hills WTPs. Thesefacilities were chosen because they represent awide range of flows and water quality constituentconcentrations with regards to all seven WTPsand will be used to represent the other facilities.The Pine Hills WTP has the lowest H2S and low-est average total organic carbon (TOC) concen-trations, the Conway WTP has midrangeconcentrations of H2S and TOC in the raw wellwater, and the Navy WTP has a higher concen-tration of H2S in its two wells.

Process Testing Protocol

The three facilities have the same basic flowscheme and attributes: raw water wells, ozonegeneration with liquid oxygen as the feed gas andfine-bubble diffusion dissolution system, ozoneresidual sampling and monitoring, chlorination,

and storage and pumping. The overall protocolfor testing involves:� Locating the sample lines for ozone residual

monitoring. � Operating at a constant well flow through one

ozone contactor, with the same wells operat-ing continuously throughout the testing.

� Setting the ozone-applied dose to a constantlevel for selected wells for steady state flow.

� Sampling the selected wells for water qualitydata, such as H2S concentration, pH, temper-ature, oxidation reduction potential (ORP),and dissolved oxygen (DO).

� Transferring the ozone residual monitoringdevice from the nonoperating contactor to thesecond sample point location on the operat-ing contactor.

� Calibrating the ozone residual devices.� Performing ozone demand and decay tests.� Gathering samples for DBP formation poten-

tial tests and for other water quality parame-ters.

The testing started with the base-appliedozone dose, or “base dose,” resulting in an ap-proximate ozone residual of 0.1 mg/L, whichrepresents the dose required to achieve com-plete oxidation of hydrogen sulfide in the rawwell water. Subsequent ozone-applied doses of0.5, 1.0, 1.5, and 2.0 mg/L above the base dosewere also used for testing. For each appliedozone dose, ozone decay tests were performed,along with trihalomethane formation poten-tial (THMFP) tests.

Conway Water Treatment Plant

Setup and MethodologyThe reporting sample point for ozone resid-

ual at this facility is sample point No. 2 (SP 2).The on-line ozone analyzer is mounted to theside of the contactor and gathers its samples froma sample line feeding into cell No. 2 of ContactorNo. 1. There is a sample pump that helps drawthe water out of the contactor and through theanalyzer header, which assists with lowering thesample line residual time. For this testing proce-dure, a bypass line was opened to increase theflow through the sample lines drawn for sample

point 1 and sample point 2, reducing the resi-dence time in the sample piping. The flowthrough the sample lines was measured using agraduated beaker and a stopwatch. Each flow testwas performed three times for the bypass lineand analyzer flows. The flow through the bypassline, which was measured to be approximately4.23 gal per minute (gpm), is the total for SP 1and SP 2. The flow through the analyzers wasmeasured to be approximately 0.39 gpm. Thiscorresponds to a flow of 2.5 gpm from SP 2, witha lag time of 15 seconds.

CalibrationThe calibration of the ozone analyzers was

performed by placing the two ozone analyzerunits in series. For 10 minutes, the readingsfrom the analyzers were recorded at 15-secondintervals. Concurrently, every 2 minutes a grabsample was taken and analyzed for ozone con-centration using a spectrophotometer, and allresults were recorded. After the calibrationcycle was completed, the recorded measure-ments from both analyzers and the grab sam-ples were plotted against time. If the grabsamples are close to the analyzer readings andare within ±1 standard deviation from the av-erage analyzer reading, the analyzers are con-sidered calibrated. The analyzers at Conwaywere not adjusted after the calibration testing.

Results

Raw Water Well TestingDuring the ozone process testing, OUC staff

performed raw water well tests on the wells thatwere in operation during the testing. The testsfor the raw water wells included: H2S concentra-tion, temperature, pH, ORP, and DO. Table 1shows the results from the raw water well testing.

Disinfection Byproduct Formation Potential Reduction and Hydrogen Sulfide

Treatment Using Ozone Greg Taylor, Charles DiGerlando, and Christopher R. Schulz

Greg Taylor, P.E., is senior project managerwith CDM Smith in Orlando; CharlesDiGerlando, P.E., is senior engineer withOrlando Utilities Commission; andChristopher R. Schulz, P.E., is senior vicepresident with CDM Smith in Denver.

F W R J


The H2S concentrations are used to help definethe “base ozone dose” for hydrogen sulfide oxi-dation and confirm the applied ozone doses uti-lized during testing.

Ozone Demand CharacteristicsThe average H2S concentration from the

three Conway WTP operating wells was 2.53mg/L. For test scenario B1, the raw water wastreated with an applied ozone dose of 10 mg/L(~0.1 mg/L ozone residual at SP 2), which repre-sents an ozone-to-sulfide ratio of approximately4:1. Table 2 shows the scenarios performed, thecorresponding ozone dose, well flow, and ozoneproduction for each scenario. The testing wasperformed in the order of B4, B3, B1, B2, and B6.

Scenario B2 and B5 were performedunder the same conditions. With multiple peo-ple running various tests, the nomenclature forthe operating scenarios were slightly miscom-municated the first day. The applied ozonedoses were the overriding factor for the testingscenarios and were used to correlate the differ-ent naming conventions. The DBP testing forscenario B2, with an applied ozone dose of 11.5mg/L, was repeated the second day, and giventhe name of B5. The testing for Conway oc-curred over two calendar days and allowedfine-tuning of the testing procedures, coordi-nation, and result reporting.

Ozone Decay CharacteristicsBefore the decay tests were performed,

the plant was operated at a steady appliedozone dose (depending on trial run) and aflow of 16.5 mil gal per day (mgd) for a mini-mum of 30 minutes to obtain a steady ozoneresidual and dose for the raw water. For eachscenario, the decay test was performed twice.Figure 1 shows the decay test results for thefirst test performed for each scenario

The data show a logarithmic decay of theozone residual in the water. The natural log ofthe ratio of measured ozone concentration toinitial ozone concentration data were then plot-ted against time in order to get the decay coeffi-cients at the various ozone-applied doses. Theslope of the trend line of each of these scenariosis the decay coefficient for the ozone decay ateach applied dose. Table 3 presents the averagedecay coefficients. The decay data show theozone decay rate that will be utilized when de-signing the ozone system to prevent any possibleozone residual carry-over from the contactors tothe ground storage tanks.

Trihalomethane Formation Potential After each decay test was performed, and be-

fore changing the applied ozone dose for the nextscenario, samples of the treated water were taken

Table 3. Conway Water Treatment Plant Average Ozone Decay Coefficients

Table 1. Conway Water Treatment Plant – Raw Water Well Test Results

Table 2. Conway Water Treatment Plant Ozone Testing Scenarios

Figure 1. Conway Water Treatment Plant Ozone Decay Results (First Test)



from the last sample point at the back of the con-tactor. This sample was then taken to the OUCwater laboratory and a simulated distribution sys-tem (SDS) test was performed to determine theTHMFP of the treated water. As stated previously,Scenario B5 is a repeat sample of scenario B2(11.5 mg/L applied dose). Figure 2 shows the SDSresults and Figure 3 shows a 48-hour THM con-centration for each scenario. The 48-hour timeperiod was selected based upon the target designwater age for the water distribution system.

These data indicate that there is not a sig-nificant impact of ozone dose on the THMFP ofthe treated water. The variability of ozone appli-cation and residuals could have impacted theconsistency of DBP testing. If sidestream injec-tion and/or a more consistent ozone dose andozone residual can be achieved, DBP testingshould be performed again.

Navy Water Treatment Plant


ual at this facility is sample point No. 1 (SP 1).The on-line ozone analyzer is mounted to theside of the contactor and gathers its samples froma sample line feeding into cell No. 2 of ContactorNo. 1. After the ozone analyzers, the sample linescome to a common header where a samplepump helps draw the water out of the contactor,lowering the sample line residual time, andpumps it back to the top of the contactor for re-treatment. A rotameter is used to measure flowthrough the sample line pumping system.

For this testing procedure, the pumped flowwas measured using the rotameter, which wascalibrated by the OUC water production opera-tors. Flow through the on-line analyzers wasmeasured using a graduated beaker and a stop-watch. Each test was performed three times forthe analyzer flows. The flow through the samplepump was measured to be approximately 8 gpm(4 gpm from each sample point), and the flowthrough the analyzers was measured to be ap-proximately 0.2 gpm. This represents a lag timefor SP 1 of approximately 3 seconds.


performed in the same manner as for the Con-way WTP. After the calibration cycle, the SP 1 on-line analyzer was adjusted down 0.3 and the SP 2analyzer was adjusted down 0.1.

Results

Raw Water Well TestingDuring the ozone process testing, OUC

Figure 2. Conway Water Treatment Plant Trihalomethane Formation Potential for Each Scenario

Figure 3, Conway Water Treatment Plant 48-Hour Trihalomethane Concentrations for Each Scenario

Table 4. Navy Water Treatment Plant – Raw Water Well Test Results




staff performed raw water well tests on Wellnumber 1, the well that was in operation dur-ing the testing. The tests for the raw water wellincluded: H2S concentration, temperature, pH,ORP, and DO. Table 4 shows the results fromthe raw water well testing.


one operating Navy WTP well was 2.02 mg/L.For test scenario B1, the raw water was treatedwith an applied ozone dose of 8 mg/L (~0.1mg/L ozone residual at SP 1). This representsan ozone-to-sulfide ratio of approximately 4:1.Table 5 shows the scenarios performed, thecorresponding ozone dose, well flow, andozone production for each scenario. The test-ing was performed in the order of B3, B5, B1,B4, and B2.

Ozone Decay CharacteristicsBefore the decay tests were performed, the

plant was operated at a steady applied ozonedose (depending on trial run) and flow (5.7mgd) for a minimum of 30 minutes to obtain asteady ozone residual and dose for the raw water.For each scenario, the decay test was performedtwice. Figure 4 shows the decay test results forthe first test performed for each scenario.

The data show a logarithmic decay of theozone residual in the water for all but the B1 sce-nario. The natural log of the ratio of measuredozone concentration to initial ozone concentra-tion data were then plotted against time in orderto get the decay coefficients at the various ozone-applied doses. The slope of the trend line of eachof these scenarios is the decay coefficient for theozone decay at each applied dose. Table 6 pres-ents the average decay coefficients. The decaydata show the ozone decay rate that will be uti-lized when designing the ozone system to pre-vent any possible ozone residual carry-over fromthe contactors to the ground storage tanks.

Trihalomethane Formation PotentialAfter each decay test was performed, and

before changing the applied ozone dose for thenext scenario, samples of the treated water weretaken from the last sample point at the back ofthe contactor. This sample was then taken to theOUC water laboratory and an SDS test was per-formed to determine the THMFP of the treatedwater. Figure 5 shows the SDS results and Fig-ure 6 shows a 55-hour THM concentration foreach scenario. The 55-hour samples have theclosest water age to the OUC distribution sys-tem target water age, which is 48 hours. The ap-plied chlorine dose for the B3 test was 0.5 mg/Lless than the other samples. This lower chlorinedose caused the free chlorine residual to drop

Table 5. Navy Water Treatment Plant Ozone Testing Scenarios

Figure 4 . Navy Water Treatment Plant Ozone Decay Tests (First Test)

Table 6 . Navy Water Treatment Plant Average Ozone Decay Coefficients


Table 7. Pine Hills Water Treatment Plant – Raw Water Well Test Results


below 0.2 mg/L after the 41-hour sample wasanalyzed. The THMFP testing is to be stoppedafter the chlorine residual drops below 0.2 mg/L.

As a policy, OUC designs the distributionsystem for a maximum water age of 48 hours.At the 55-hour testing period, there does notappear to be an advantage to an increasedozone dose to reduce the THMFP of the treatedwater. There does seem to be a 10-12 mg/L dropin THMFP with the additional 1 mg/L of ozoneadded to the water; however, these tests shouldbe repeated following construction of the ozoneimprovements at this WTP, and more data col-lected for a lesser number of time intervals tobetter establish this relationship.

Pine Hills Water Treatment Plant


ual at this facility is sample point No. 2 (SP 2).The on-line ozone analyzer is mounted to theside of the contactor and gathers its samples froma sample line feeding into cell No. 2 of ContactorNo. 1. After the ozone analyzers, the sample linescome to a common header where a samplepump helps draw the water out of the contactor,lowering the sample line residual time, andpumps it back to the top of the contactor for re-treatment. There is not a rotameter on thisheader, so the flows were measured using a stop-watch and a graduated beaker.

Each test was performed three times for theanalyzer flows. The flow through the samplepump was measured to be approximately 5.3gpm (2.65 gpm from each sample point), and theflow through the analyzers was measured to beapproximately 1.07 gpm. This represents a sam-ple lag time for SP 2 of 1.2 seconds.


performed following the same procedure as theConway WTP. After the calibration cycle, the SP2 online analyzer was adjusted up 0.1 to matchthe SP 1 analyzer and the grab samples.

Results

Raw Water Well TestingDuring the ozone process testing, OUC staff

performed raw water well tests on the wells thatwere in operation during the testing. The testsfor the raw water well included: H2S concentra-tion, temperature, pH, ORP, and DO. Table 7shows the results from the raw water well testing.


Pine Hills WTP operating wells was 0.64 mg/L.

Figure 5 . Navy Water Treatment Plant Trihalomethane Formation Potential for Each Scenario

Figure 6. Navy Water Treatment Plant 55-Hour Trihalomethane Concentrations for Each Scenario

Table 8. Pine Hills Water Treatment Plant Ozone Testing Scenarios


For test scenario B1, the raw water was treatedwith an applied ozone dose of 2 mg/L (~0.1mg/L ozone residual at SP 2). This represents anozone-to-sulfide ratio of approximately 3.13:1.Table 8 shows the scenarios performed, the cor-responding ozone dose, well flow, and ozoneproduction for each scenario. The testing wasperformed in the order of B5, B1, B2, B3, and B4.

Ozone Decay CharacteristicsBefore the decay tests were performed, the

plant was operated at a steady applied ozone dose(depending on trial run) and flow (11.6 mgd) fora minimum of 30 minutes to obtain a steadyozone residual and dose for the raw water. Foreach scenario, the decay test was performedtwice. Figure 7 shows the decay test results for thefirst test performed for each scenario..

The data show a logarithmic decay of theozone residual in the water. The natural log ofthe ratio of measured ozone concentration toinitial ozone concentration data were then plot-ted against time in order to get the decay coeffi-cients at the various ozone-applied doses. Theslope of the trend line of each of these scenariosis the decay coefficient for the ozone decay ateach applied dose. Table 9 presents the averagedecay coefficients. The decay data show theozone decay rate that will be utilized when de-signing the ozone system to prevent any possibleozone residual carry-over from the contactors tothe ground storage tanks.

Trihalomethane Formation Potential After each decay test was performed, and

before changing the applied ozone dose for thenext scenario, samples of the treated water weretaken from the last sample point at the dischargeof the contactor. This sample was then taken tothe OUC water laboratory and an SDS test wasperformed to determine the THMFP of thetreated water. Figure 8 shows the SDS results andFigure 9 shows a 48-hour THM concentrationfor each scenario. The data indicate that an ad-ditional 1.5-2.0 mg/L of applied ozone dose willyield a potential 5 µg/L reduction in THM for-mation. However, it is not efficient to apply thisadditional dose of ozone to the raw water for amarginal improvement to the THMFP when thewater at this WTP has an already low THMFP.

Disinfection Byproduct Impacts

The Pine Hills WTP has the highest waterquality (lowest H2S, lowest TOC) out of all of theWTPs. Figures 8 and 9 show a minimal (5 µg/L)reduction of THMs, with an additional 1.5-2.0mg/L applied ozone dose above the base dose.

At the Conway WTP, the data at the 48-hour time frame indicate that there is not an

Table 9. Pine Hills Water Treatment Plant Average Ozone Decay Coefficients

Figure 7. Pine Hills Water Treatment Plant Ozone Decay Tests (First Test)


Figure 8 . Pine Hills Water Treatment Plant Trihalomethane Formation Potential for Each Scenario


advantage to applying more ozone to the rawwater to reduce the THMFP of the treatedwater. In addition, when looking over the com-plete 96-hour time period for the SDS testing,the data show no impacts as the lines continu-ally cross each other, indicating no consistentreduction in the THMFP of the water.

At the Navy WTP, the 55-hour time framedata do show a 10-12 µg/L drop in THMFP withthe additional 1 mg/L of ozone added to thewater; however, this test was stopped after 41hours and not allowed to proceed to 96 hours,like the other samples, due to the chlorine resid-ual dissipating below 0.2 mg/L after 41 hours.

The THM formation data collected duringthe testing period do not suggest a definitive cri-terion for applying additional ozone to thewater for DBP control. The addition of ozoneabove the doses required for H2S oxidation doesappear to have an impact on the THMFP of theraw water at the facilities. However, an accurateprediction of the impacts cannot be deter-mined—only a possible trend that warrantsfurther analysis. It is recommended to performTHMFP tests again at each plant after the sys-tems have been upgraded to sidestream injec-tion. The reduced ozone residual variability inthe sampling system will improve operationalcontrol and more accurate testing results. ��

Figure 9. Pine Hills Water Treatment Plant 48-Hour Trihalomethane Concentrations for Each Scenario



The FWPCOA RegionVIII has outdone it-self once again! The

region, along with the local chapters ofFSAWWA (Region V) and FWEA (SouthwestChapter), put on the seventh Annual Waterand Wastewater Expo, where several hundredpeople came to get their continuing educationtraining. Along with the courses that were ap-proved for both continuing education units(CEUs) and professional development hours(PDHs), was an exposition floor where vendorsfrom all over the state came to show theirwares. I would like to recognize the efforts ofCherie Wolter, Ron Cavalieri, Jason Sciandra,Justin Martin, Jon Meyer, Jack Green, Fred

Gliem, and all of the instructors and vendorswho participated. Over 60 door prizes werehanded out and the comments from the stu-dents, vendors, and those who passed throughthe floor show were outstanding. I am person-ally looking forward to next year’s event.

The Florida Department of Environmen-tal Protection (FDEP) Operator CertificationProgram (OCP) has temporarily stopped itscomputer-based testing services for drinkingwater, wastewater, and system operators. Thecontract with Applied Measurement Profes-sionals (AMP), which permits FDEP to offercomputer-based testing, expired on August 28of this year. For those wanting to take the stateexam, you may schedule a paper-and-pencilexam through the Department. The requiredform is available on the FDEP website and canbe faxed to its office for the November and De-cember dates. Once the Department has re-

ceived your location request, you will receiveconfirmation of the location, date, and time.For additional information please go tohttp://www.dep.state.fl.us/water/wff/ocp/index.htm, “Pencil-and-Paper Exam FrequentlyAsked Questions.” The FDEP is currently in theprocess of procuring a computer-based testingvendor in order to continue to offer the samelevel of testing services. The Department an-ticipates that the examination services will re-sume in January 2015. If you have questions,visit the OCP website or call the office at (850)245-7500.

The deadline for you to meet your educa-tional requirement for license renewal is fastapproaching. Some of us like to get those cred-its with hands-on training, some like the class-room setting, and others like to acquire thosecredits in the privacy and leisure of their ownhome. The FWPCOA can meet any of yourwater and wastewater educational needs in thesetting that you prefer. Along with trainingfrom our local regions, the state will put on an-other state short school in March.

Another great way of acquiring your CEUcredits is by sharing your knowledge. The As-sociation is divided into 13 regions, and theirindividual training programs, as well as ourstate programs, are always looking for good in-structors. You are allowed to gain credit for thehours you teach and your involvement willbenefit the entire industry. If you would like toshare your knowledge with your industry in alocal region, or at the state level, please visit ourwebsite or call the training office at (321) 383-9690 for more information.

By the time you read this message the No-vember board of directors meeting will have al-ready concluded. I’m hesitantly excited aboutthe November meeting (actually being held inOctober), which will include the Rim BishopBirthday Bash. I heard the last bash was remi-niscent of a line from the movie Jaws: “Elevenhundred men went in the water; three hundredand sixteen men come out.” I’m going to tryand stay out of the water. If I survive the bashI’ll be able to bore you all with at least one morearticle.

As of now, I have not identified the loca-tion of the December board meeting; however,I will post it in my next article. I hope to seeyou soon! ��

Jeff PoteetPresident, FWPCOA

An Expo, Testing, Teaching, and Meetings All Increase Water Knowledge

C FACTOR



The David L. Tippin Water TreatmentFacility (Facility) is an advanced watertreatment facility in Tampa, with a ca-

pacity up to 120 mil gal per day (mgd) con-sisting of coagulation, flocculation,sedimentation, ozonation, and biofiltrationprocesses. The finished water has seasonallyexhibited a very high chlorine/chloramine de-mand, up to 5 mg/L as chlorine, which has in-curred a higher chemical cost. Previousresearch at this facility suggested that biofil-tration is the culprit (Marda et al, 2008). Theissue of high chlorine demand with ozone andbiofiltration was also reported by Wilczak et al(2003) and Vokes (2007) and attributed tobiofiltration not performing well.

Biofiltration prevents regrowth in the dis-tribution system by relying on bioactivity inthe filters to consume biodegradable carbon,increasing the biostability of the finished waterin the distribution system (Escobar et al, 2001;Urfer et al, 1997; Wang et al, 1995; Price et al,1993; LeChevallier et al, 1992; Rittmann et al,1989; Bouwer and Crowe 1988). When the nu-trient molar ratio of 100:10:1 (carbon:nitro-gen:phosphorus) required by heterotrophicbacteria is met, assimilable organic carbon(AOC) becomes the limiting factor of biofilmformation (LeChevallier et al, 1991).LeChevallier et al (1996) found a direct corre-lation between AOC and regrowth potential.

As a single cause of increased chlo-rine/chloramine demand in biofiltration hasnot been identified, multiple avenues aimingat improving the postfilter chlorine/chlo-ramine demand have been investigated.Amirtharajah (1993) examined the impor-tance of the air scouring during the process of

filter backwash, where air and water were usedsimultaneously to create a phenomenonknown as “collapse-pulsing.” A high-speedcamera was used to confirm the theoreticalbasis of the method. Collapse-pulsing in-creases the detachment of particles duringbackwash, preventing mud-ball formation andincreasing filter effluent quality after back-wash.

Ahmad et al (1998) found that collapse-pulse backwashing, followed by traditionalwater backwash with at least 25 percent bedexpansion, produced water with lower AOCthan without air scouring. It also producedlower AOC than a nonbiological filter, and thetype of filter backwash water impacts filterperformance as well. Lower levels of AOC areassociated with nonchlorinated backwashwater (Ahmad et al, 1998). Overall, nonchlo-rinated water for filter backwash has providedmany advantages over chlorinated water. Theremoval of aldehydes, AOC, and total organiccarbon (TOC) is higher, while chlorine/chlo-ramine decays more slowly (Vokes, 2007; Milt-ner et al, 1995; Wang et al, 1995).

Granular activated carbon (GAC) gener-ally performs better than anthracite for biofil-tration. Ahmad and Amirtharajah (1998)found that bacteria remain better attached toGAC than anthracite during backwash. Notonly could GAC hold three to eight timesmore biomass than anthracite, it also providesbetter aldehyde removal at colder tempera-tures and establishes biofilms quicker than an-thracite (Urfer et al, 1997; Wang et al, 1995).Anthracite filter performance is negatively af-fected by chlorinated backwash water moresignificantly than GAC (Urfer et al, 1997).

In multiple studies, organic carbon hasbeen identified as the limiting nutrient forbiofilm formation and regrowth in finishedwater and correlated with AOC formation(Chandy and Angles, 2001; LeChevallier et al,1992; LeChevallier et al, 1991). Biofilm forma-tion is more prominent in waters with in-creased chloramine decay rates (Chandy andAngles, 2001). LeChevallier et al (1991) iden-tified the limiting nutrient molar ratio of100:10:1 (carbon, ammonia-nitrogen, and or-thophosphate-phosphorus) for biofilm for-mation. Based on this ratio, where biofilmdevelopment is being prevented, Lauderdale etal (2012) investigated the addition of nutrientsto biofilters, where biofilm development is apositive trait.

Carbon, nitrogen, and phosphorus werefirst quantified in prefiltration water. TheNH4-N and PO4-P were determined to be thedeficient nutrients and subsequently added tothe top of the filters. The basis for this is two-fold. For one, if sufficient nitrogen and phos-phorus are not available, bacteria in the filtersare not removing the maximum amount ofbiodegradable carbon. Secondly, bacteria pro-duce more biofilm when “stressed,” meaning anutrient in limited supply may increase theamount of biofilm material formed in the fil-ters, leading to excessive clogging. Lauderdaleet al (2012) also investigated the addition ofhydrogen peroxide to provide microorganismswith increased dissolved oxygen and depoly-merize the extracellular polymeric substances(EPS) and observed a 60 percent decrease interminal headloss during the 10-day study.

The primary materials of biofilm are EPS,with polysaccharides as one of the major com-ponents (Tsuneda et al, 2003). Liu et al (2006)identified the relationship between nutrientsand microbial production and secretion of

Effects of Backwash Water and ChemicalAddition on Biofiltration

Hongxia Lei, Dustin W. Bales, and Maya A. Trotz

Hongxia Lei is the water quality assuranceofficer with City of Tampa; Dustin W. Balesis a graduate intern with City of Tampafrom the University of South Florida inTampa; and Maya A. Trotz is an associateprofessor at the University of South Floridain Tampa.

F W R J

Table 1. Water Quality of the Feed Water to the Pilot Plant


EPS. Lauderdale et al (2012) found that nutri-ent addition decreased terminal head loss byapproximately 15 percent, possibly attributedto less EPS. The significance and implicationsof soluble microbial products (SMPs) inwastewater treatment, of which EPS is a con-stituent, are well documented in a review pub-lished by Barker and Stuckey (1999). TheSMPs are the assortment of organic productsand byproducts from microbial reactions in-volved in biological treatment. While mostSMP research is in wastewater treatment, it islikely that SMPs and EPS have effects that havenot been quantified on biological filtration indrinking water treatment. Mauclaire et al(2004) studied the effect of EPS on slow sandfiltration, attributing at least 7 percent of clog-ging to EPS, a greater percentage than that ofparticle deposition.

The goal of this study was to examine theeffects of nonchloraminated backwash water,nutrient addition, media type, and hydrogenperoxide addition on biologically activated fil-ters to improve their operation at the Facility,which is currently backwashed by water drawnfrom the clearwells, with the chloramine levelaround 5 mg/L. This study encompasses ex-tensive test results from a two-year period ofpilot and full-scale investigations, a time framemuch longer than most studies, which allowedmore realistic technology transfer from pilotto full-scale. The filter performance underchloraminated and nonchloraminated back-wash water was compared back-to-back andconfirmed by cycling between chloraminatedand nonchloraminated water, with each con-dition run over several months. Similarly, thechemical additions were run for an extendedperiod of time (at least one month). Some ofthe findings from this study deviate from pre-viously published literature and reflect thecomplexity of water treatment technology.

Materials and Methods

Experimental Design The pilot plant filters used in this study,

emulating the full-scale system at the Facility,take water directly from the full-scale plantafter coagulation and ozonation and beforebiofiltration. As a result, the water quality ofthe feed water to the pilot plant does not varyas much as the raw water. Constituents rele-vant to this study are summarized in Table 1,covering the same time span of this study fromMay 2011 through December 2012.

Four factors were evaluated for their po-tential efficacy in improving the performanceof biofiltration utilizing the six 1×1 ft sq filtersat the pilot plant. The detailed experimentalmatrix is summarized in Table 2. The first con-

dition was media material, with anthracite1

(0.8 – 1.0 mm) placed in the first two filters la-beled as anthracite #1 and #2 GAC2 (0.8 – 1.0mm) and in the remaining four filters labeledas GAC #1, #2, #3, and #4, all at a depth of 24in. of media atop 12 in. of sand3 (0.45 – 0.55mm). These six filters had been in operationfor several years, with the GAC media over twoyears old and the anthracite media acclimatedfor three months before this study. As a result,the adsorption removal of TOC was minimal.

The second condition was the effect ofchloramine present in backwash water. To testthis condition, all six filters were run for threemonths with chloraminated backwash water,followed by five months of nonchloraminatedbackwash water, all at a filter loading rate of 1gal per minute per sq ft (gpm/ft2). At thatpoint, the backwash operation was automated,allowing higher loading rates to be tested withmore frequent backwashes. To confirm thefindings with a loading rate identical to a full-scale plant (typically about 2 gpm/ft2), the fil-ters were switched back to chloraminatedbackwash water for two months and thennonchloraminated backwash water for fourmonths. Filters were run for at least onemonth before any samples were collected toallow the bioactivity to recover whenever thebackwash water was changed from chlorami-nated to nonchloraminated water.

Both nutrient and hydrogen peroxide ad-dition were studied with nonchloraminatedbackwash water, summarized in Table 2. Withthe DOC removal up to 1.5 mg/L, NH4-N (asammonium chloride) and PO4-P (as phos-phoric acid) were added at a dose of 0.351mg/L and 0.078 mg/L, respectively, to an-thracite #2, GAC #3, and GAC #4 from the topof these filters, allowing a direct performance

comparison between GAC and anthracite. Thisdose will meet the C:N:P molar ratio require-ment of 100:10:1 with both N and P a little bitin excess to overcome the adsorption of N or P.Following nutrient addition, hydrogen perox-ide was added from the top of the same threefilers: anthracite #2, GAC #3, and GAC #4.During the course of each condition, sampleswere collected and tested for pH, temperature,chlorine demand, TOC, AOC, and carboxylicacids. Samples were taken from before and afterthe pilot filters, as well as from the full-scalesystem, allowing a comparison of performance.

Pilot Plant The pilot filters were operated at loading

rates of 1-2.5 gpm/ft2, with turbidity, headloss,and flow rate recorded to supervisory controland data acquisition (SCADA) software. Tur-bidity was measured by an online analyzer4

verified monthly and calibrated every threemonths; headloss and flow rate were alsomeasured by online analyzers5,6 that were cal-ibrated or inspected every six months. Allother measurements were done by taking sam-ples to the on-site water quality laboratorytransported on ice in coolers. The GAC usedin the pilot plant was acquired from the full-scale system after being in use for over twoyears and was already bioactive. Anthracite wasacquired new and had not been previouslyused; therefore, the filters were run for threemonths prior to performing any tests. Thethree-month acclimation period was chosenbased on findings reported by Velten et al(2011), which showed that bioactivity reacheda plateau, based on DOC removal and adeno-sine triphosphate (ATP) analysis, after ap-proximately two months.

Table 2. Summary of Experiments Performed to Study the Effects of Nutrient and Hydrogen Peroxide on Filter Performance



Backwash water was stored in a 1,000 Lhigh-density polyethylene (HDPE) tank.When chloraminated water was to be used forbackwash, finished water from the clearwell ofthe full-scale Facility filled the tanks. Whennonchloraminated water was to be used, efflu-ent water from the pilot filters was collectedand pumped into the tank.

Nutrient addition was accomplishedusing a 120 L HDPE tank combined with aCole-Parmer MasterFlex peristaltic pump,with the nutrients feeding into the top of thefilters. The ammonia solution was preparedfrom ACS (American Chemical Society)-gradeammonium chloride (NH4Cl)7. The phospho-rus solution was prepared from ACS-grade 85-percent phosphoric acid7. Hydrogen peroxideaddition was accomplished using the same sys-tem using ACS-grade 30-percent hydrogenperoxide8.

When the project first started, filterswere manually backwashed twice a week(Tuesday and Friday), with their headlossrecorded immediately prior to backwash.Starting in December 2011, or eight monthsinto studying the effect of chloraminatedbackwash water, the filters were put on an au-tomatic backwash sequence identical to theone utilized for the full-scale Facility filtra-tion system, using run time, turbidity, andheadloss as the set points. All subsequentstudies, including the confirmation tests forchloraminated and nonchloraminated back-wash water and the impact of nutrient andhydrogen peroxide additions, were per-formed with automated filter backwash. Therun time set point was changed from 80hours to 120 hours in April 2012 to accom-modate increased filter run time; it was fur-ther raised to 150 hours in May 2012. Thebackwash procedure consisted of first drain-ing the filter water level to 1 ft above themedia, followed by 90 seconds of air scour-ing at 3 standard cu ft per minute per sq ft(scfm/ft2). Low-rate backwash at 7 gpm/ft2

began in tandem with 45 seconds of air

scouring and continued for another 45 sec-onds, followed by 7 minutes of high-ratebackwash at 17 gpm/ft2. High rate backwashis followed by 1 minute of low-rate backwashto finish the cycle and the filter is then putback in service.

Analytical Methods Chlorine demand, measured by how fast

the monochloramine would decay, was ob-tained in duplicate by dosing the waters withammonia and chlorine sequentially at a 1.05:1molar ratio of ammonia to chlorine, and laterincreased to 1.2:1 to avoid the potential break-point chlorination issues due to the ammoniadeficiency. Monochloramine was used for thechlorine demand study to better simulate full-scale conditions, as this was the type of chlo-rine applied to the finished water formaintaining disinfectant residual. The targetchloramine dose was 8 mg/L, with an adjustedpH of 7.70. This pH was selected to better sim-ulate full-scale conditions. Total chlorine wasmeasured 45 minutes after dosing.

Following day one, total chlorine wasmeasured daily at approximately the sametime during the remaining four days by Stan-dard Method 4500G-Cl Chlorine (Residual),diethyl-p-phenylenedamine (DPD) colori-metric method (Standard Methods, 2005).Chlorine used for dosing was prepared from a5-6 percent hypochlorite solution7. Ammoniaused for dosing was prepared from ACS-gradeammonium chloride7. Phosphate buffer solu-tion and DPD indicator solution were pur-chased factory prepared8. Potassium iodidewas prepared from ACS-grade potassium io-dide7.

The TOC was measured according toStandard Method 5310C ( Standard Methods,2005)9. The AOC was analyzed following Stan-dard Method 9217B ( Standard Methods, 2005)by an outside laboratory10. Three carboxylicacids, including acetate, formate, and oxalate,were analyzed according to an ionic chro-matographic method reported by Peldszus etal (1996), Kuo (1998), and Kuo et al (1996),

with minor modifications11. In summary, 20mg/L mercury chloride was used as a preser-vative and a sample holding time of 17 dayswas adopted. Postozone samples were not aer-ated since ozone residuals were consistentlyclose to nondetect. The calculated method de-tection limits (MDLs) were 3.7, 2.5, and 2.5µg/L for acetate, formate, and oxalate, respec-tively. Carboxylic acid analysis beginning inMay 2012 was performed by an outside labo-ratory12 using the same method and identicalinstrument.

The EPS was analyzed in both backwashwater and filter media for all six pilot plantbiofilters. The media samples were extractedfollowing a protocol published by Lauderdaleet al (2011) to allow the differentiation of freeand bound EPS, and quantified using theDubois method (1956). This method quanti-fies polysaccharides, which are the dominantcomponents of EPS. For filter backwash water,the procedure was similar to the EPS meas-urement on the media. Since the dislodging ofbiofilm was already accomplished duringbackwash, the sonication step was not needed.The backwash water was directly centrifugedand the supernatant analyzed for free EPS andpellet after centrifugation was extracted andanalyzed for bound EPS with the same proce-dure previously mentioned. The media sam-ples were taken from the top layer of the filterswhen the filters had a headloss between 4 and6 ft to ensure similar conditions and similarstage of EPS development between backwashcycles. Immediately after the media sampleswere collected, the filters were forced to back-wash to enable the collection of backwashwater samples under similar conditions.

Results

Effect of Nonchloraminated BackwashWater and Media Type

Carboxylic Acid Removal At the full-scale Facility, finished water

with a typical chloramine residual of around 5mg/L is used to backwash filters, which was re-ported to possibly have a negative impact onbiofilter performance (Miltner et al, 1995).Table 3 shows the total concentrations of thethree carboxylic acids in the feed/influent andin the effluent water for both GAC and an-thracite filters at the pilot plant. The carboxylicacid concentrations in the feed water variedgreatly from 41 µg/L-C to 162 µg/L-C, most ofwhich were removed by the biofilters, with theremoval percentage consistently over 70 per-cent. For the same time period, the removal ofcarboxylic acids at the full-scale plant averaged

Table 3. Total Carboxylic Acid Removal: Comparison of Chloraminated and Nonchloraminated Backwash Water




at 82 ± 6 percent. Apparently, the GAC filters at the pilot plant achievedsimilar removals of carboxylic acids to the full-scale GAC filters, whileanthracite consistently underperforms GAC throughout all conditionsin regards to the removal of carboxylic acids.

For both GAC and anthracite filters, nonchloraminated backwashwater didn’t improve the removal of carboxylic acids, and the filterloading rates also did not result in any difference in removal. This couldbe attributed to the fact that the removals are fairly high with chlo-raminated backwash water and there is no room left for improvementwith nonchloraminated water. The TOC removal showed similar trend-ing (results not presented), but is overall lower than the removal of car-boxylic acids, typically in the range between 18 to 45 percent.

Chlorine Demand of Filter Effluent Chlorine demand for both influent and effluent of all the filters was

another metric used to evaluate the impact of nonchloraminated back-wash water and filter media on filter performance. The same set of watersamples from Table 3 were first dosed with chloramine at the target con-centrations and chloramine residuals were measured daily. Figure 1shows the chloramine decay kinetics over a five-day period under one ofthe test conditions and Figure 2 shows the summary of chlorine demandfor all the samples generated in Table 3; the chlorine demand during thesame time period for full-scale filters is also presented in Figure 2 as a ref-erence point. Note that in the figure, the full-scale filters were alwaysbackwashed with chloraminated water, with the filter loading rate fluc-tuated around 2 gpm/ft2 during the entire pilot study. The error bars inFigure 2 merely reflected water quality variation rather than the exper-imental error because they were averaged based on samples collectedmonthly over a three-month period for chloraminated backwash water



Figure 1. Chlorine Curves with Nonchloraminated Backwashand Filter Loading Rate of 1 gpm/ft2

Figure 2. Comparison of Chloraminated andNonchloraminated Backwash Water on ChlorineDemand With Different Filter Loading Rates

Figure 3. Impact of Chloramine in Filter Backwash Water onFilter Run Time (BW – Backwash)

and a five-month period fornonchloraminated backwashwater.

Results in Figure 2 haveshown a pronounced effect ofchloraminated backwash wateron chlorine demand. When thefilters were backwashed withchloraminated water, the chlorinedemand of the filter effluent atthe pilot plant was similar to thefull-scale plant. Pilot GAC filtersat the loading rate of 1 gpm/ft2

performed a little bit better thanfull-scale filters, which treatedwater at a loading rate of 2gpm/ft2. When the loading rate ofpilot plant was increased to 2gpm/ft2, no difference in chlorinedemand was observed betweenpilot GAC filters and the full-scalefilters. Overall, anthracite mediaperform significantly worse thanGAC with the difference betweenthe two media more pronouncedwhen the loading rate was in-creased from 1 to 2 gpm/ft2.

In contrast, under nonchlo-raminated filter backwash condi-tions, with a filter loading rate of 1 gpm/ft2

(Figure 1), all four GAC filters, as well as thetwo anthracite filters, exhibit similar chlo-ramine decay kinetics and chlorine demanddespite different media and other differencesobserved among the six filters, such as filterrun time and removal of TOC and carboxylicacids. This is also true for the 2.5 gpm/ft2 filterloading rate as demonstrated in Figure 2whenever nonchloraminated water was usedfor filter backwash. In both cases, the chlorinedemands for pilot plants for both GAC andanthracite filter effluent were significantlylower than full-scale filter effluent, which wasstill backwashed with chloraminated water.

In the full-scale plant, the chlorine de-mand for filter effluent is higher than the in-fluent; in other words, the biofiltration addsadditional chlorine demand to the water beingtreated, which was undesirable and causedproblems to the distribution system’s waterquality maintenance. Results in Figure 2 sug-gest that this problem could be eliminated byswitching to nonchloraminated backwashwater and the resulted improvement will bepersistent regardless of the filter loading rateand media type.

Filter Run Time Lower chlorine demand is one benefit

with nonchloraminated water for filter back-wash. Another benefit is a significant longer

filter run time (Figure 3), which was recordedafter December 2011 when the pilot plantbegan to be backwashed by the fully auto-mated SCADA system. Figure 3 is presentedfollowing the temporal order and grouped byvarious testing conditions shown in the x-axis.In this figure, the pilot and full-scale plantswere operated with the same filter loading rate,the same backwash procedures, and samesource water; however, the backwash water forfull-scale always contained chloramine withresidual up to 5 mg/L, depending on the levelin the clearwell where the backwash water wasdrawn. The pilot plant was initially back-washed with the same type of chloraminatedwater, as shown in Figure 3, and switched tononchloraminated water to study the impacts.The improvement in filter run time for bothanthracite and GAC filters from nonchloram-inated backwash water is significant.

Near the end of the test, anthracite andGAC showed 70 percent and 84 percent im-provement, respectively, over full-scale filters,on average. These results also suggest that ittakes time for biological activity to reach itsfull potential. On day 18, after nonchlorami-nated backwash, longer filter run time was al-ready observed and continued to increase overthe course of the entire testing period fornonchloraminated backwash water. The si-multaneous improvement in filter effluentchlorine demand was noticed, as well as after

the switch of backwash water, asdiscussed previously. Another les-son learned was the ability to recog-nize the differences among thefilters of identical conditions. FiltersGAC #3 and GAC #4 can be bestused to demonstrate this point anddespite the same conditions, GAC#4 consistently had much longer fil-ter run time under all test condi-tions. In summary, all four GACand both anthracite filters exhibiteddifferences in filter run time to var-ious extents. As a result, it isstrongly recommended that biofil-tration be studied, at least in dupli-cate.

Mechanism of Filter PerformanceImprovement

To elucidate the underly-ing mechanism for improved filterperformance, the effluent from oneGAC filter was treated by 0.45 mi-crometre (µm) filter and the differ-ence in chlorine demand before andafter filtration was studied underchloraminated and nonchlorami-nated filter backwash conditions.

The results are shown in Figure 4, normalizedby initial concentration.

When nonchloraminated backwash waterwas used, no discernible difference was notedafter the sample was treated by the 0.45 µm fil-ter. With chloraminated backwash water, the0.45 µm filtration decreased chlorine demandsignificantly. On day 3, a 15 percent improve-ment was observed, in contrast to the minis-cule difference when nonchloraminated waterwas used for filter backwash. These resultshave suggested that particles small enough toavoid being retained by the GAC but largeenough to be stopped by a 0.45 µm filter is theexplanation for the improved chloraminedecay. Marda et al (2008) observed the similarphenomenon with chloraminated backwashwater, but provided no solution to resolve thisissue. The results presented in Figure 4 clearlydemonstrated that the nonchloraminated fil-ter backwash water could help filters better re-tain particles larger than 0.45 µm and cutdown chlorine demand.

Effect of Nutrient and Hydrogen PeroxideAddition

The purpose of nutrient and hydrogenperoxide addition is to better manage bioac-tivity on the filter media and control the se-cretion of EPS. To evaluate the benefits to theFacility, both were studied at its pilot plant, but



Figure 4. Effect of 0.45 µm Filter on Pilot Granular ActivatedCarbon Effluent Chlorine Demand


with different study criteria; more specifically,the removals of TOC and carboxylic acids,chlorine demand, and filter run time. Alsostudied were turbidity, head loss, and filterloading rate, which were continuouslyrecorded by the online analyzers.

Starting in May 2012, filters anthracite #2,GAC #3, and GAC #4 had ammonia chlorideand phosphoric acid added to the top of the fil-ters to test the effect of nutrient addition onbiofilter performance. The dosed concentrationswere based on DOC using the 100:10:1 C:N:Pmolar ratio identified by LeChevallier et al(1991) as the limiting ratios for biofilm forma-tion in drinking water. Ammonia concentra-tions in the effluent of the six pilot filters were allbelow 0.1 mg/L, with the actual levels varyingamong the six filters, and the levels for ammoniaadded to the filters were not statistically higherthan those without ammonia addition.

Phosphorous concentrations in the efflu-ent showed a different trending. They were allbelow 0.01 mg/L for the six pilot filters onemonth after three of the six filters were dosedwith the nutrient. However, monitoring con-ducted two months later showed the phos-phorous levels for nutrient treated filtersaveraged 0.016 mg/L versus less than 0.010mg/L for filters without nutrient addition, ap-parently attributing to nutrient breakthrough.These results suggested that enough nutrientswere dosed and any benefit from nutrient ad-

dition should show if such benefit does exist.Figure 5 shows the removal for TOC and

carboxylic acids and the associated chlorinedemand as a result of nutrient addition. Forboth GAC and anthracite filters, nutrient ad-dition clearly had no effect on the removal ofTOC and carboxylic acids, or chlorine de-mand. There may be a slight negative effect ofnutrient addition on the removal of TOC andcarboxylic acids for GAC media, but it iswithin statistical error. Additionally, no differ-ence was observed in regards to filter head lossand filter run time. The results presented herefailed to confirm the benefits reported byLauderdale et al (2012). This is likely due tothe complexity of the water treatment process,the different source water, and other unknownfactors.

Following the nutrient addition, hydro-gen peroxide dosed at 1 mg/L and 2 mg/L wastested. Hydrogen peroxide of 1 mg/L wasadded for 70 days to filters anthracite #2, GAC#3, and GAC #4, while the rest of the filters hadno addition and served as controls. The effectsof hydrogen peroxide addition can then beevaluated by comparing the performance ofanthracite #2 versus anthracite control, andGAC #3 and GAC #4 versus GAC controls. Af-terward, hydrogen peroxide dose was in-creased to 2 mg/L and applied to the samethree filters continuously for the following 34days. No significant differences in TOC re-moval, carboxylic acid removal, or chlorine

demand were observed for either anthracite orGAC media with either 1 or 2 mg/L hydrogenperoxide added.

Filter run time is summarized in Figure6. Because the tests were run over six months,source water was expected to change over thetime period. As a result, controls were used totake into account changes in source water. Foranthracite media, nutrient and hydrogen per-oxide addition appears to have a positive effecton filter run time based on relative differencebetween the test and control filters; however,GAC does not exhibit the same results.

The GAC #4 seems to be positively affectedby either nutrient or hydrogen peroxide addi-tion, but GAC #3 showed the opposite effect.The absolute filter run time of GAC #3 had in-creased when 1 mg/L hydrogen peroxide wasadded to the filter. However, when the relativeratio between GAC #3 and the GAC control(GAC #1 or 2) was compared, its performancestayed flat with nutrient and 1 mg/L hydrogenperoxide addition and became worse when hy-drogen peroxide was fed at 2 mg/L. This illus-trated again the importance of evaluatingbiofilters at least in duplicate to account for vari-ations between filters. Overall, the improvementin filter run time from either nutrient or hydro-gen addition is inconclusive for GAC media anda slight advantage is observed for anthracitemedia. This could be due to the better biologicalactivity and retention exhibited by GAC filters



Figure 6. Impact of Nutrient and Hydrogen Peroxide Additionon Filter Run Time

Figure 5. Effect of Nutrient Addition on Total Organic CarbonRemoval, Carboxylic Acid Removal, and ChlorineDemand

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(Ahmad et al, 1998), and as a re-sult, there is not much room leftfor improvement.

To help better understandthe results and elucidate the rea-sons for the observed differencefrom Lauderdale et al (2012),EPS was monitored in filterbackwash water and on themedia. The results are summa-rized in Figure 7. In filter back-wash water, less than 15 percentof EPS was present as unbound;on the media, EPS was stillmostly bound, but the unboundEPS concentration became moresignificant. These data haveshown EPS levels are greatly af-fected by seasonal temperaturechanges. The relatively warmermonth of August directly re-sulted in higher EPS, both in fil-ter backwash water and on themedia, regardless of the mediatype. The seasonal difference wasmore pronounced in the pilotplant than the full-scale plant,likely due to the fact that unlikethe full-scale plant, the pilotplant used nonchloraminatedwater for filter backwash and hadmore bioactivity.

In filter backwash water, nu-trient and hydrogen peroxide ad-dition did not cause anydifference to EPS concentrations.Despite the difference observedamong the six filters, the EPS lev-els for the controls of both GACand anthracite fell well within the same rangeas the testing filters. The GAC #4 did exhibitrelatively higher EPS concentration in thebackwash water, which seems to be consistentwith this filter’s exceptionally longer filter runtime. For some reason, which could be betterperforation in the supporting plate in the un-derdrain system, this filter’s backwash appar-ently is more efficient and removes more EPS.Overall, regardless of chemical additions, thelevel of EPS in backwash water seems to corre-late with filter run time and can be used as arough indicator of the potential filter run time.

On the media, as expected, higher levelsof EPS were observed on GAC when comparedto anthracite. The levels of EPS on both mediaare slightly higher than EPS on sand (Mauclaireet al, 2004), but still within the same order ofmagnitude. No direct comparison could bemade with data reported by Lauderdale et al(2012), where EPS on the media was reported

in the unit of mg/L. In this study, nutrient ad-dition did not decrease EPS for GAC or an-thracite media when compared to the controlgroups, which explained the lack of improve-ment in filter performance from the nutrientaddition. Hydrogen peroxide addition, how-ever, did decrease EPS for GAC filters withGAC #3 and #4 showing less EPS compared totheir corresponding control filters.

Despite the improvement in EPS levels,the filters with hydrogen peroxide addition didnot show longer filter run time (Figure 6) orless chlorine demand (Figure 5), nor did theyshow better removal of TOC and carboxylicacids (Figure 5). Based on these results and thesignificant differences from previously pub-lished literatures (Lauderdale et al, 2012), fur-ther studies on nutrient and hydrogenperoxide addition are strongly recommendedto include a more diversified coverage of geo-logical locations and source waters.

Implications to Full-Scale Plantand Future Studies

This study has revealed thehigh variability of biofilter perform-ance, in spite of identical configura-tions and operational procedures. Itis recommended that future studiesbe conducted with duplicate or eventriplicate filter columns, which ischallenging considering the scale anddemanding nature of pilot testing.Yet, capturing and being able to fore-see variability of biofilters is an im-portant and often neglected issue.Each filter’s run time in this study notonly differs by up to 50 percent com-pared to each other, it also varies by20 to 30 percent between back-washes. It should be noted that de-spite the significantly different runtime among the different filters, thechlorine demand and removal per-centages of TOC and carboxylic acidswere very close under identical con-ditions. The data suggest that as runtime increases, variance increases. Fil-ter run time is very sensitive to vari-ations in source water quality, withextreme peaks and drops withinshort time spans compared to othermetrics of filter performance.

Based on pilot plant studyresults, the recommended resolu-tion for the high chlorine demandproblem in finished water is to usenonchloraminated water for filterbackwash. The estimated savingsfor chlorine and ammonia is about20 to 30 percent of their currentcost, depending on time of the year

and water demand. Approximately one thirdof the savings is from ammonia and two thirdsfrom chlorine, depending on market prices.Additional savings should come from thelower volume of backwash water required dueto longer filter run times. Collectively, theseadd up to a total savings of around $270,000,assuming the cost to produce water remainsaround $500 per mil gal (MG). More impor-tantly, the biofilters will be optimized and poseless operational challenges, especially whendealing with the control of nitrification prob-lems at the furthest end of the distribution sys-tem.

Conclusion

The performance of biofiltration wasstudied using a multitude of factors, aiming atsolving the high chlorine demand problem infinished water via filter optimization. Based on

Continued from page 40Figure 7. Effect of Nutrient and Hydrogen Peroxide Addition

on Extracellular Polymeric Substances Concentrationsin (a) Backwash Water and (b) Filter Media

All samples were run in quadruplicate with errors less than 20 percent

this study, increased bioactivity should be de-sired, as it can improve filter performance. Thechloramine in the backwash water had astrong negative effect on the filter performancewith respect to both chlorine demand and fil-ter run time. A switch to nonchloraminatedbackwash water exhibited the most significantimprovement on the biofiltration system outof all the factors studied, and subsequently ledto the largest cost savings. Using nonchloram-inated backwash water, the chlorine demandin filter effluent remained the same as the in-fluent, representing a 50 percent improvementfor anthracite and a 30 percent improvementfor GAC when compared with chloraminatedbackwash water. The filter run time was in-creased by approximately 40 percent as a re-sult of using nonchloraminated backwashwater, which directly translated into a 40 per-cent decrease in backwash water usage.

Altogether, switching to nonchlorami-nated water for filter backwash will result in anestimated annual cost saving of $270,000 onceimplemented at the full-scale Facility. Nonchlo-raminated backwash water did not show anysignificant effects on the removal of TOC orcarboxylic acids. Generally, GAC media per-form better than anthracite media, but an-thracite still performs sufficiently well for manyutilities to consider due to the significant costdifference between GAC and anthracite.

This study showed no major effect fromthe addition of nutrient and hydrogen perox-ide. Their potential benefit judged by the re-moval of TOC and carboxylic acids, chlorinedemand of the effluent, and filter run time wasvery minor. Nutrient addition did not causesignificant impact on EPS concentrations onthe media. Hydrogen peroxide addition de-creased EPS levels, but without any associatedbenefits. Higher levels of EPS were observedon GAC when compared to anthracite and inthe relatively warmer summer month of Au-gust when compared to December. EPS in fil-ter backwash water appeared to be a roughindicator of the effectiveness of backwash andsubsequently affected filter run time.

Acknowledgements

The authors kindly acknowledge the fi-nancial and staffing support from City ofTampa Water Department. Paula Lowe, JonDocs, Niloofar Pishdad, Charles Ketter, andJason Cohen at the David L. Tippin WaterTreatment Facility provided assistance on vari-ous aspects of this study. The authors also thankDr. James R. Mihelcic at the University of SouthFlorida for his comments to this article.

Florida Water Resources Journal • November 2014 43Continued on page 44


Footnotes

1 Anthracfilter Inc., Niagara Falls, N.Y.2 ActiCarb, Dunnellon, Fla.3 Standard Sand & Silica Company, Daven-

port, Fla.4 HACH, model SC100 controller with a

1720E sensor, Loveland, Colo.5 Endress+Houser, model PMD70, Green-

wood, Ind.6 Endress+Houser, magmeter Promag 10,

Greenwood, Ind.7 Fisher Scientific, Fair Lawn, N.J.8 Sigma Aldrich, St. Louis, Mo.9 Teledyne Tekmar TOC Fusion, Thousand

Oaks, Calif.10 MWH Laboratories, Monrovia, Calif.11 Dionex ICS 3000, Sunnyvale, Calif.12 Underwriters Laboratory, South Bend, Ind.

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Earn CEUs by answering questions from previous Journal issues!

Contact FWPCOA at [email protected] or at 561-840-0340. Articles from past issues can be viewed on the Journal website, www.fwrj.com.

Members of the Florida Water &Pollution Control Association (FWPCOA)may earn continuing education unitsthrough the CEU Challenge! Answer thequestions published on this page, basedon the technical articles in this month’sissue. Circle the letter of each correctanswer. There is only one correctanswer to each question! Answer 80percent of the questions on any articlecorrectly to earn 0.1 CEU for yourlicense. Retests are available.

This month’s editorial theme is

Water Treatment. Look above each set ofquestions to see if it is for wateroperators (DW), distribution systemoperators (DS), or wastewateroperators (WW). Mail the completedpage (or a photocopy) to: FloridaEnvironmental Professionals Training, P.O.Box 33119, Palm Beach Gardens, FL33420-3119. Enclose $15 for each setof questions you choose to answer (makechecks payable to FWPCOA). You MUSTbe an FWPCOA member before you cansubmit your answers!

Operators: Take the CEU Challenge!

1. The Orlando Utility Commission (OUC) ozone generationequipment uses __________ as feed gas.a. carbon dioxide b. liquid oxygenc. ammonia d. nitrogen

2. Which of the following is a recommendation made followingthis study?a. A feed rate exceeding H2S demand by 2 mg/L should be

implemented.b. Trihalomethane formation potential (THMFP) should be

run again after sidestream injection is implemented.c. No further study is required.d. The study should be expanded to investigate the

effectiveness of combining ozone and chloramination.

3. Of the facilities studied, the ________________ WaterTreatment Plant was determined to have the highest qualityraw water.a. Pine Hills b. Disneyc. Conway d. Navy

4. For the purposes of this study, the base dose of ozone is theamount that produces an ozone residual concentration of ____mg/L.a. 0.1 b. 0.5c. 1.0 d. 2.0

5. Sodium hypochlorite was added to the water to produce achlorine residual of ___ mg/L after 96 hours as part of thesimulated distribution system test.a. 0.1 b. 0.2c. 0.5 d. 1.0

Disinfection Byproduct Formation Potential Reduction and Hydrogen

Sulfide Treatment Using Ozone

Greg Taylor, Charles DiGerlando, and Christopher Schulz

(Article 2: CEU = 0.1 DS/DW)

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1. The Stage 1 and 2 D/DBPR applies to all community andnontransient water systems delivering water disinfected by anyagent other thana. chlorine. b. Monochloramine.c. ultraviolet light. d. chlorine dioxide.

2. In the lime softening process, removal of _____________ istypically optimized at pH 10.3.a. natural organic matter (NOM)b. total activated carbon (TOC)c. colord. calcium hardness

3. In conventional treatment, ____________ must follow_____________ to remove additional color, TOC, and disinfectionbyproducts (DBPs).a. pH adjustment, filtration b. coagulation, softeningc. disinfection, aeration d. coagulation, filtration

4. The analytical method used in measuring dissolved organic carbonincludes which of the following steps not taken when measuringtotal organic carbon?a. Removing inorganic carbonb. Oxidizing remaining carbon to carbon dioxidec. Measuring carbon dioxided. Sample filtration

5. To comply with regulatory locational running annual averagemaximum contaminant levels for total trihalomethaneconcentration, the author recommends a peak totaltrihalomethanes (TTHM) target concentration of ___ mg/l.a. 40 b. 30c. 64 d. 48

Treatment of Organic-Laden Surface Water for Total Organic Carbon

Steven J. Duranceau (Article 1: CEU = 0.1 DS/DW)



Many drinking water plants usewater from rivers, reservoirs, orlakes as their raw water sources.

These surface waters invariably contain somelevels of pathogens that must be inactivatedprior to distribution, as well as organic ma-terial (such as decaying plant matter). To en-sure that water is safe to drink, the U.S.Environmental Protection Agency (EPA)mandates that a sufficient quantity of disin-fectant be added to generate a residual con-centration at the customer’s tap.Disinfectants can react with the organic ma-terial in drinking water to form disinfectantbyproducts (DBPs), and epidemiologicalstudies have identified that certain classes ofDBPs are human carcinogens. The DBPsform when water that contains total organiccarbon (TOC), also referred to as natural or-ganic matter (NOM), is mixed with certainforms of chlorine. The DBP precursor com-pounds are a subset of NOM and are foundin natural waters. The NOM is most com-monly found in surface water where organicmatter frequently enters the water body fromrunoff, and also from aquatic organisms.Public water systems using surface watermust disinfect the water prior to delivery tothe first customer.

What is Total Organic Carbon?

The amount of carbon bound in an or-ganic compound is known as TOC and isoften used as a nonspecific indicator of waterquality. With passage of EPA’s Safe DrinkingWater Act, TOC analysis emerges as a quickand accurate alternative to the classical bio-chemical oxygen demand (BOD) and chemi-cal oxygen demand (COD) tests traditionallyreserved for assessing the pollution potentialof wastewaters. The TOC is determined by re-moving inorganic carbon, oxidizing the re-maining carbon to carbon dioxide usingcombustion or chemical oxidation with per-sulfate, and measuring the carbon dioxideproduced using a conductivity detector ornondispersive infrared detector. Dissolved or-ganic carbon (DOC) is determined similarlyto TOC, but the sample is filtered through a0.45 µm filter prior to oxidation. The ultravi-olet absorbance (UVA) is measured by filter-ing a sample with a 0.45 µm filter andmeasuring absorbance at 254 nm. The specificultraviolet absorbance (SUVA) is calculated bydividing UVA by DOC and multiplying by anappropriate unit correction factor.

Surface waters are found to contain ap-preciable amounts of TOC, and the removal

of color and DBPs can be related to TOC re-moval. The natural organic content of Floridasurface water is typically high, with TOC val-ues often greater than 15 mg/L and true colorvalues as high as 700 platinum-cobalt units(PCU). Historically, surface water treatmentfacility costs and performance decision mak-ing procedures were primarily based on tur-bidity and pH. With the implementation ofEPA’s Stage 2 DBP Rule, TOC must now be in-tegrated into the decision making processwhen it comes to treatment selectionprocesses.

Figure 1 illustrates a representation ofhumic acid, a DBP precursor, and one com-ponent of natural organic matter. Instead ofvolumetric size, NOM is commonly charac-terized by molecular weight (MW), molecularweight fractionation, and resin isolation intohydrophobic, intermediate, and hydrophilicfractions (Fabris et al, 2008; Kim et al, 2010).Polysaccharides and peptidoglycans are con-sidered high MW compounds, whereas aro-matics (i.e., lignin and tannin derivatives) areabundant in the intermediate-high MW frac-tions of NOM. Nonhumic, aromatic andaliphatic amines, amino acids, polysaccha-rides, and proteins are considered hydropho-bic low molecular weight compounds.

Regulatory Considerations

Regulations drive the need to treat or-ganic-laden surface waters. In December 1998,EPA published the Stage 1 Disinfectant/Disin-fection Byproducts Rule (D/DBPR) that es-tablished treatment techniques for the controlof precursors to disinfectant byproducts. Thissection requires enhanced coagulation or en-hanced softening to remove a certain percent-age of organic carbon based on the sourcewater’s TOC and alkalinity for all public watersystems using surface water or groundwater

Treatment of Organic-Laden Surface Water for Total Organic Carbon

Steven J. Duranceau

Steven J. Duranceau, Ph.D., P.E., isassociate professor and director, ESEI,department of civil, environmental, andconstruction engineering, at the Universityof Central Florida in Orlando.

F W R J

Figure 1. Representative Structure of Humic Acid, a Component of Total Organic CarbonSource: Stevenson (1994)


under the direct influence of surface. In Janu-ary 2006, EPA published the Stage 2 D/DBPRthat required water utilities to comply with areduced maximum contaminant level (MCL)of 80 µg/L for total trihalomethanes (TTHMs:chloroform, bromoform, and dibromochloro-and dichlorobromo-methane) and a newMCL of 60 µg/L for the sum of five haloaceticacids (HAA5: monochloro-, dichloro-,trichloro-, monobromo, and dibromo-aceticacid) at each individual monitoring location ina distribution system (i.e., locational runningannual averages).

The rule sets up several alternatives to re-moval, one of which is SUVA of source or fin-ished water. The SUVA is an analysis of waterthat uses UV absorbance and DOC levels. Pre-vious studies established a relationship be-tween SUVA and the levels of humicsubstances that are removed during enhancedcoagulation and/or enhanced softening. IfSUVA levels meet certain requirements, it islogical for the enhanced coagulation or soft-ening to be unnecessary. Stage 1 D/DBPR al-lows an exemption from costly TOC removalrequirements if SUVA levels for source or fin-ished water are below 2.0 L/mg-m. It also pro-vides for SUVA-level substitutions whencalculating TOC removal compliance.

The EPA has set required TOC removallevels for water systems that use conventionaltreatment, as shown in Table 1. Water systemsthat use surface water and conventional filtra-tion treatment are required to remove speci-fied percentages of organic materials,measured as TOC, that may react with disin-fectants to form DBPs. Removal is to beachieved through a treatment technique (en-hanced coagulation or enhanced softening).Enhanced coagulation has been identified asone of the most effective treatment methodsfor lowering TOC concentrations, and subse-quently, DBP formation potential.

As a result of the D/DBP Rule, there hasbeen increasing emphasis by the water com-munity on the removal of NOM from watersupplies; important NOM removal options arecoagulation, granular activated carbon (GAC)adsorption, membrane filtration, and anionexchange. Of these processes, coagulation isthe most widely used in the water industry.But, when coagulation cannot remove ade-quate concentrations of NOM so that DBPscan be controlled, other treatment technolo-gies, such as GAC, nanofiltration, and anionexchange may need to be used. Chemical soft-ening has been used with variable success.Also, ozone and advanced oxidation may alsobe utilized, but typically must be combinedwith another unit operation.

Total Organic Carbon Removal by Softening

Removal of NOM is significant to thedrinking water community in that color, TOC,and DBPs are NOM subsets and controlled bywater treatment due to regulatory and/or aes-thetic constraints. Not all NOM or TOC pro-duces color or regulated DBPs; hence, TOC isa more universal measure of organic materialin drinking water. Most if not all of the TOCremoved during lime softening is in the formof nonpurgeable dissolved organic carbon(NPDOC). The TOC can be in a suspended orgaseous form in some drinking water sources;however, these TOC forms are either easily re-moved during drinking water treatment or arenot DBP precursors, which prior to disinfec-tion are in the form of NPDOC.

Bench-scale tests demonstrate the impor-tance of magnesium hydroxide precipitationand NOM characteristics on precursor re-moval by softening. The maximum percentageTOC removal achieved for lime and soda ashdosages evaluated for nine waters examinedranged from 23 to 50 percent (Thompson,1997).

Investigators have found that softeningremoved TOC, but was less effective for TOCremoval than coagulation; addition of coagu-lants during softening enhanced TOC removaland the chemical structure affected TOC re-moval. A survey of water treatment plants par-ticipating in the information collection rule(ICR) found that 30 to 40 percent of TOC wasremoved during lime softening in the 2=4mg/L and 4-8 mg/L TOC groups, respectively.They suggested additional TOC removalshould not be required by regulation after 0.2meq/L Mg removal, 0.8-1.2 meq/L alkalinityremoval, or if major changes of existing facil-ities were required to accommodate the moreslowly settling magnesium hydroxide, or

Mg(OH)2, floc, or the additional sludge (Clarkand Lawler, 1996). Increasing doses of ferricsulfate to 9.5 mg/L Fe+3 were observed to in-crease TOC removal to 75 percent, as softeningpH increased to 10.3 (Quinn et al, 1992).

Bench-scale jar testing using waters fromnine utilities found that TOC removal was cor-related with increasing TOC concentration,hydrophobic TOC fraction, and the magne-sium removed during softening. A significantrelationship between the TOC removed andmagnesium removed was observed (Thomp-son et al, 1997). Softening of Mississippi Riverwater was found to remove less TOC than co-agulation, although higher molecular weighthydrophobic organic solutes were removed byboth processes (Semmens and Staples, 1986).Liao and Randtke (1986) suggested coprecip-itation was the primary mechanism for re-moval of organic solutes during softening, andorganic removal was limited to anionic com-pounds, which could absorb onto calcium car-bonate (CaCO3) solids.

Calcium and Magnesium Precipitation

During lime softening, calcium removaldue to CaCO3 precipitation increases with pHto pH 10.3. At pH 10.3, nearly all of the cal-cium or carbonate alkalinity has been precip-itated as CaCO3 because of equilibrium (K2,Ksp). Removal of calcium hardness is typicallyoptimized at pH 10.3 in lime softening. PastpH 10.3, there is not enough carbonate alka-linity to precipitate the calcium solubilizedfrom lime. Some slight additional calcium re-moval will be realized in a caustic softeningprocess, but typically the vast majority ofCaCO3 precipitation is complete at pH 10.3.Because of Mg(OH)2 equilibrium, adequatemagnesium removal is typically not achieved

Table1. Required Total Organic Carbon Removal Requirements for Conventional Treatment Plants1, 2

Source: EPA, June 2001. Stage 1 Disinfectants and Disinfection Byproducts Rule Fact Sheet. EPA 816-F-01-014



until pH ≥ 10.8. The exact pH for optimizedCaCO3 and desired Mg(OH)2 precipitationmay differ slightly from 10.3 and 10.8 due tocalcium and magnesium interactions withother solutes. However, CaCO3 and Mg(OH)2

precipitation occurs in different pH rangesand can be related to TOC removal.

The EPA and Water Research Foundationhave investigated the removal of color, TOC,and DBP precursors (Taylor, 1984; Taylor,1986; Randtke, 1999). The studied waters varyfrom a soft water with low magnesium con-tent and low TOC concentration (Lawrence,Kan.) to a hard water with high magnesiumcontent and high TOC concentration (GrandForks, N.D.). The TOC varied directly withboth calcium and magnesium hardness forthese three waters and the TOC removal in-creased with pH for each. Prior to pH 10.3,the TOC removal varies from approximately20 to 30 percent. The initial total hardness re-duction of approximately 50 percent at pH10.3 is due to CaCO3 precipitation and occurssimultaneously with 20 to 30 percent TOC re-ductions. Past pH 10.3 TOC reduction is in-creased by approximately 25 percent and isassociated with approximately 30 percent re-duction of initial total hardness, which is dueto Mg(OH)2 precipitation. The TOC removaldue to CaCO3 precipitation was limited to 30percent and the TOC removal was increasedto 55 percent when Mg(OH)2 was precipi-tated, which indicates that removal of mag-nesium hardness in a softening process willincrease TOC removal.

Coagulation

Coagulation is a treatment process thatincludes chemical addition, rapid mixing, andflocculation. The TOC removal can be influ-enced by the type of coagulant dosage, pH,mixing, water quality change, and the order ofchemical addition. Maximum TOC removaltends to occur at pH values between 5 and 6and low alkalinity water may require the addi-tion of lime to maintain the pH in this range.Full-scale treatment plants have demonstratedthat moving the location of the disinfectionprocess to a point following coagulation andsedimentation, or modifying the coagulationprocess for increased removal of organic ma-terials (or both), can result in substantial re-ductions in DBP formation. Coagulation canbe an effective pretreatment technique subse-quent to GAC or membrane filtration in thatit removes particles that might clog GAC beds,which reduces the frequency of carbon regen-eration and replacement, and it removes TOC,notorious for shortening membrane lives.

Typically, magnesium coagulation at pH 11.3to 12.0 accompanied 80 to 98 percent color re-moval, 20 to 40 percent TOC removal, and 40to 65 percent trihalomethane formation po-tential (THMFP) removal. Optimum THMFPreduction was always accompanied by opti-mum TOC and color reduction (Taylor, 1984).Alum used as a coagulant aid at pH 11.5 in-creases THMFP, TOC, and color removal byabout 10 percent.

Enhanced coagulation and enhancedsoftening were developed specifically for con-ventional filtration treatment systems whererapid mix and flocculation were followed bygravity sedimentation; this is the normal treat-ment scheme for most surface water plants.However, some plants that do not use this con-ventional scheme can be adversely affected bypracticing enhanced coagulation or enhancedsoftening, as these treatment techniques werenot intended to be utilized in nonconventionalfiltration treatment systems. For example,some systems do not use gravity sedimenta-tion for particulate removal; instead, liquidalum and a polymer chemical are dosed at op-timum conditions to create pin floc, which isremoved through a pressurized clarifying fil-ter. Enhanced coagulation in this treatmentscheme could easily lead to floc particle for-mation larger than what the system is designedto filter. Prematurely clogged filters andshorter filter runs are likely to result under en-hanced coagulation conditions. Similar oper-ating problems are anticipated for other formsof alternate treatment technologies or filtra-tion systems.

Granular Activated Carbon

The EPA has identified the best availabletechnology (BAT) for achieving compliancewith the maximum contaminant levels forboth TTHMs and HAA5 as treatment withGAC having a 10-minute empty bed contacttime (EBCT) and a 180-day replacement fre-quency with chlorine as the primary and sec-ondary residual disinfectant. The GACadsorption is an effective technology em-ployed for the removal of NOM, and is typi-cally used as a medium as a filter-adsorber inmany water treatment plants (Babi et al, 2007).Normally, 80 to 90 percent of the NOM meas-ured in raw water sources can be removed byGAC adsorption (Roberts and Summers, 1982;Karanfil et al, 2007). Research by Owen andcolleagues (1998) has shown that rapid small-scale column tests (RSSCTs) can be success-fully used to predict NOMbreakthrough-behavior GAC columns interms of TOC and UV 254; additionally, it hasbeen determined that several RSSCTs should

be performed with differing batches of influ-ent waters that represent the seasons of inter-est. The GACs with large surface areas andpore volumes in pores >1 nm and basicpHPZC values should be selected for DBP pre-cursor control. Removal of high molecularweight NOM during conventional treatmentprocesses prior to filtration significantly in-creases the operational time of GAC for DBPformation control. Therefore, the impact ofconventional treatment processes on GAC ad-sorption and DBP formation control shouldbe evaluated in designing and operating GACadsorption systems.

Membranes

Membrane processes have been demon-strated to effectively and economically removeDBP precursors in water containing high con-centrations of organic matter. There are fourkinds of membranes: reverse osmosis (RO),nanofiltration (NF), ultrafiltration (UF) andmicrofiltration (MF). Table 2 presents anoverview of TOC and DBP precursor removalusing membranes. In general, membraneswith a molecular weight cutoff (MWCO) ofless than 1,000 daltons are necessary to removesubstantial levels of NOM (Taylor, Thompson,and Carwell, 1987); a MWCO of less than 500is usually necessary to reject greater than 90percent of DBP precursors (Duranceau andTaylor, 2010; Metsamuuronen et al, 2014).

Low pH and high ionic strength can de-crease the apparent molecular size of organicmatter and its electrostatic repulsion from themembrane surface and then decrease its re-moval. Bromide has been shown to have a sig-nificant effect on the formation of DBPs afterchlorination of membrane permeates; in gen-eral, its removal by membranes is 20 to 70 per-cent. As the membrane MWCO decreases, theTOC removal increases. The resulting increasein the bromide-to-TOC ratio favors the for-mation of brominated DBPs after chlorina-tion. However, if enough of the TOC isremoved by the membrane, the absolute con-centrations of the DBPs will be limited, re-gardless of relatively high bromide levels.

Yoon and researchers (2005) have re-ported significant NOM removal of 70 to 86percent with hydrophobic polyethersulfone(PES) and sulfonated PES membranes, al-though less than 10 percent rejection wouldhave been expected when the average MW ofNOM and membrane pore sizes is considered.This is attributed to hydrophobic interactionand electrostatic exclusion between the hy-drophobic and charged membrane surfaceand the NOM molecules.

The NF membranes are able to remove



compounds from macromolecular size tomultivalent ions, but at higher transmem-brane pressure as compared to UF. Almostcomplete NOM rejections were achieved withNF membranes having cut-off values in therange of 100–400 daltons (Duranceau andTaylor, 2010). However, NF is more susceptibleto fouling when treating surface water sup-plies, as was noted by Reiss and colleagues(1999).

Because of the larger pore sizes (0.005 to5µm), the removal of NOM with MF and UFis substantially less than that observed with ei-ther NF or RO. By polypropylene 0.2µm MFmembrane, it demonstrated a 15 percent re-moval of TOC and total THMFP from a flow-ing stream. By 0.05µm ceramic tubularmembrane on blended river waters with an av-erage TOC concentration of 8.2mg/L, it wasreported reduced to approximately 30 percentremoval of TOC and the THMFP was reducedby 10 to 20 percent by both the 0.05µm and0.2µm ceramic tubular membrane. The re-moval of DBP precursors can be improved bythe feedwater pretreatment of UF and MF. Thetwo most common types of pretreatment arecoagulant and polyaluminum chloride (PAC)addition. Using MF, with the addition of 10 to15 mg/L of ferric chloride, the removal ofTHMFP from surface water could be increasedfrom 15 to 60 percent. Using 0.05µm ceramictubular membranes, the removal of TOC wasfrom 30 to 60 percent and the removal ofTHMFP improved approximately 30 percent.Table 3 lists TOC removals for treatment usingadsorbents such as PAC or iron oxide particlesin combination with MF and UF.

Anion Exchange

The NOM in water contains significantamounts of high-molecular-weight solubleand colloidal humic and fulvic acid anions,which are often associated with the solubleand colloidal iron, manganese, and silica in thewater. In the 1960s, macroporous weak-baseanion (WBA) resins were used to remove colorfrom river water, and in the 1970s, macrop-orous strong-base anion (SBA) resins wereused to successfully treat highly coloredgroundwater. Also in the 1970s, polyacrylicstrong-base resins were developed, which wereless prone to irreversible fouling comparedwith the standard polystyene resins in univer-sal use. Following the discovery of the forma-tion of THMs and other DBPs in water in themid-1970s, various strong- and weak-baseanoin exchange resins were found to be capa-ble of removing DBP precursors from water.Experimental use of resins for TOC removal

Table 2. Summary of Trihalomethane Formation Potential Removal by Membrane Technology, Water Source, and Pretreatment

Table 3. Removal of Total Organic Carbon by Ultrafiltration and Microfiltration with Adsorbent Pretreatment

Table 3 Notes:MF=microfiltration UF=ultrafiltrationPAC=powered activated carbon IOP=iron oxide particlesContinued on page 50


continued through the mechanism of NOMremoval by strong-base resins. Magnetic ion-exchange resins have emerged as an effectivemethod for treating surface water for organicmatter (Comstock and Boyer 2014; Drikas etal, 2011; Mergen et al, 2008).

In slightly acidic, neutral, and alkalinewater, the acidic functional groups on NOMare negatively charged. Thus, TOC moleculesare naturally attracted to anion exchangeresins, which contain positively charged aminefunctional groups attached to a polystyrene orpolyacrylic polymer matrix. Karpinska andcolleagues (2013) have shown that a propri-etary resin (MIEX) can remove over 89 per-cent of the DOC from the surface water. Anionexchange has been used to remove DOC andhardness simultaneously (Phetrak et al, 2014;Apell and Boyer, 2014).

Weak-base anion resins contain weaklybasic-primary, secondary, or tertiary amine-functional (exchange) groups, which are pos-itively charged (protonated) only in acidicsolution. These resins function as anion ex-changers only when the solution is pH ≤ 6.When pH is above 6, the amine functionalgroups are neutral and do not exchange ions.But, some WBA resins can function as adsor-bents for TOC at pH ≥ 6.

Strong-base anion resins contain quater-nary amine functional groups typically at-tached to a polystyrene or polyacrylic matrix.The more common macroporous polyacrylicresin types, unlike the microporous polystyeneresin types, are often used because of theirlower organic fouling potential. Both resinshave quaternary amine functional groups thatare ionized (positively charged) and functionas anion exchangers throughout the 3 to 13 pHrange. Regarding porosity, macroporous resinshave measurable Brunauer-Emmett-Teller(BET) surface area (measured by N2 adsorp-tion), whereas microporous (or gel) resinshave no measurable BET surface area. In aque-ous solution, both types of resins have appar-ent porosity because they are swollen withwater and readily allow hydrated ions to enterthe hydrated polymer (Singer, 1999).

Compared with GAC, WBA, or SBA,resins have greater sorption capacity for NOM,remove NOM faster, and are easier to regener-ate (Boening, Beckman, and Snoeyink, 1980).When operated at pH 6.5 to 8.5, the WBAresins adsorb the NOM, whereas SBA resinsoperate by the mechanism of ion exchange.Various studies reported by Singer (1999) havedemonstrated that it is not possible to reliablypredict THMFP removal based on the surro-gates of color or TOC removal.

Ozone Oxidation

Ozone has been used in the treatment ofdrinking water since the end of the 19th cen-tury (Langlas, Reckow, and Brink, 1991). Al-though the original applications of ozone weredisinfection, as experience increased, and sincethe mid-1970s, ozone has also been recognizedas an important tool in controlling halo-genated DBPs. Ozone is powerful and canreact with many organic and inorganic solutesin water. By preozonation, followed by chlori-nation at low pH, it can reach the greatest netdecrease in THM formation (Singer, 1999).High bicarbonate concentration can also helpto improve THM control by ozone. Becauseozone itself can decompose to form secondaryoxidant species, one of which is hydroxyl rad-ical (•OH), bicarbonate can act as a free radi-cal scavenger that consumes hydroxyl radicals;then, the decomposition of ozone is sloweddown, and the chance of solutes reacting withozone is increased. On the other hand, withthe reaction of hydroxyl radicals, bicarbonatecan form bicarbonate radicals, which are moremoderate radicals and may help to destroyDBP precursor sites (Malley, Edzwald, andRam, 1986; Legube et al, 1985). Weiner (1995)had shown that ozone destroys the fast-react-ing THM precursors, which are mainly acti-vated aromatic structures and can react withozone easily; then, the THM formation isslowed. Among the HAAs, trichloroacetic acid(TCAA) can be destructed by ozone easily,while dichloroacetic acid (DCAA) is unaf-fected. Some compounds, such as halogenatedketones and aldehydes, will form at greaterconcentrations as a result of prior ozonation.In general, ozone can reduce HAAs, total or-ganic halides (TOX), and THMs to a great ex-tent until the time that the water is consumed.

There are many advantages to applyingozone as an alternative to chlorine at the headof the treatment plant. It can delay or evenavoid the formation of DBPs from free chlori-nation. It can also increase the biodegradation,as well as better control tastes and odors, andremove turbidity or filtration effect. Ozonemay react with bromide to form hypobro-mous acid; then, hypobromous can continueto react with NOM to form brominated DBPs:

Lowering the O3 dosage may minimizethe formation of BrO3

- but increase the for-mation of other DBPs. On the other hand,higher O3 dosages can lead to significant BrO3

-

formation, particularly at high Br- levels and atambient pH.

Ozonation converts humic and hy-drophobic organic compounds into smallerfragments, but as it does not lead to full min-eralization of most compounds, the initialDOC concentration decreases only slightly.Oxidation may produce harmful byproductsand increases assimilable organic carbon(AOC) content, and thus, the potential for bac-terial regrowth in the distribution systems.However, these problems can be avoided bycombining oxidation with a downstream bio-logical activated carbon (BAC) process prior tothe membranes. The granular media filters arewidely used prefilters for membrane processes.The media filters capture particles of large-sizedistribution and, may reduce fouling of thedownstream membrane, if employed.

Advanced Oxidation

Advanced oxidation processes (AOPs)have been studied intensively for decades. Var-ious combinations of oxidants, radiation, andcatalyst have been developed for the removalof TOC, NOM, and organic pollutants; for ex-ample, O3/H2O2, UV/H2O2, UV/O3,UV/TiO2, Fe2+/H2O2, Fe2+/H2O2 + hv, vac-uum ultraviolet radiation, or ionizing radiation(Fujishima, 1971; Glaze et al, 1987; Legrini etal, 1993; Frimmel, 1994; Nagata et al, 1996;Fukushima et al, 2001; Thomson et al, 2002).These processes involve the generation ofhighly reactive radical intermediates, especiallythe OH radical (Glaze et al, 1987). The appealof AOPs is the possibility to gain complete ox-idation or mineralization of organic contami-nants through a process that operates nearambient temperature and pressure. Sit-nichenko and researchers (2011) reported thatgreater than 90 percent of fulvic acids could bedestroyed using a photocatalytic oxidation byoxygen using UV light and titanium dioxide insurface water over a wide range of pH (3-8).

Summary and Suggested Disinfection Byproduct

Water Quality Goals

Removal of organic solutes using a varietyof unit operation processes is unique to a givenwater source. However, some generalizationscan be made regarding softening:� Calcium Carbonate Precipitation - Generally

removes from 10 to 30 percent of the color,TOC, and DBP precursors. Has the least ca-pacity for organic removal of solids gener-ally precipitated in precipitative softening.

� Magnesium Hydroxide Precipitation - Gen-erally removes from 30 to 60 percent of theTOC and DBP precursors, and 50 to 80 per-cent of the color. Requires primary recar-



bonation to remove excess calcium if lime isused, produces excess magnesium and cal-cium sludge, and requires either additionalsedimentation basins or solids loading onfilters if excess calcium is removed.

� Iron and Aluminum Augmentation - Gener-ally removes an additional 5 to 15 percentof the color, TOC, and DBP precursors ineither calcium or magnesium precipitation.Will cause excess sludge formation. Alu-minum may be passed through the processand postprecipitate in distribution system.

� Sequential Treatment - Coagulation followingsoftening will remove additional color, TOC,and DBP precursors; however no additionalcolor, TOC, and DBP precursors will be re-moved if softening precedes coagulation.

� GAC - Normally, 80 to 90 percent of theNOM measured in raw water sources canbe removed by GAC adsorption.

� Oxidation - Various combinations of oxi-dants, radiation, and catalyst have been de-veloped for the removal of TOC, NOM, andorganic pollutants.

The TOC removal must now be taken intoaccount when evaluating treatment technolo-gies for treatment of surface water supplies.Table 4 provides a recommended listing of sug-

gested water quality goals for DBPs for com-munities seeking to establish treatment targets.

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• Babi, R.G. et al (2007). Pilot Study of the Re-moval of THMs, HAA spend DOC fromdrinking water by GAC adsorption. Desali-nation. 210, 215-224.

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Table 4. Suggested Water Quality Goals for Disinfection Byproducts



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• Liao, M. Y. and Randtke, S. J. (1986). “Pre-dicting Removal of Soluble Organic Con-taminants by Lime Softteing,” Water

Research, Vol. 20, 1, 27-35.• Malley, J.P. Jr.; Edzwald, J.K.; and Ram, N.M.

1986. Preoxidant Adsorption of OrganicHalide Formation and Granular ActivatedCarbon Adsorption of Organic Halide Pre-cursors. In Proc. 1986 AWWA Annual Con-ference. Denver, Colo.: American WaterWorks Association.

• Mergen, M.R.; Jefferson, B.; and Parsons,S.A. (2008). Magnetic ion-exchange resintreatment: impact of water type and resinuse. Water Research. 42 (8-9), 1977-1988.

• Metsamuuironen, S. et al (2014). NaturalOrganic Removal from Drinking Water byMembrane Technology. Separation and Pu-rification Reviews. 43, 1-61.

• Nagata, Y.; Hirai, K.; Bandow, H.; andMaeda, Y. (1996). Decomposition of hy-drobencoic and humic acids in water by ul-trasonic irradiation. Environ. Sci. Technol.,30, 1133–1138.

• Oliver, B.G. and Thurman, E.M. 1983. Influ-ence of Aquatic humic substance propertieson trihalomethane potential. Water chlori-nation: Environmental Impact and HealthEffects Volume 4, Ann Arbor, Mich.: AnnArbor Science Publishers Inc.

• Owen, D.M.; Chowdhury, Z.K.; Summers,R.S.; Hooper, S.M.; Solarik, G.; and Gray, K.(1998). Removal of DBP Precursors by GACAdsorption. AWWARF Project 90744.AWWARF, Denver Colorado.

• Phetrak, A. et al (2014). Simultaneous re-moval of dissolved organic matter and bro-mide from drinking water source by anionexchange resins for controlling disinfectionbyproducts. J. Env. Sciences China. 26 (6),1294-1300.

• Quinn S. R.; Hashsam, S. A.; and Ansari, N.I. (1992) “TOC Removal by Coagulation andSoftening,” Journal of Environmental Engi-neering, 118 (3), 432-436.

• Randtke S. J. et al (1999) “Precursor Removalby Coagulation and Softening,” AWWARFProject 814. AWWARF, Denver ,Colo.

• Reiss, C.R.; Taylor, J.S.; and Robert, C.(1999). Surface water treatment usingnanofiltration—pilot testing results and de-sign considerations. Desalination, 125: 97–112.

• Roberts, P. V., and Summers, R.S. (1982).Granular Activated Carbon Performance forOrganic Carbon Removal. Journal AWWA.74(2):113-118.

• Semmens, M. J. and Staples, A. B. “The Na-ture of Organics Removal During Treatmentof Mississippi River Water.” Journal AWWA,Vol. 78, 2, 76-81, Feb. 1986.

• Singer, P.C. (1999). Formation and Controlfor Disinfection Byproducts in DrinkingWater. Denver, Colo.: AWWA.

• Sitnichienko, T.N.; Vakulenko, V.F.; andGoncharuk, V.V. (2011). “Photocatalytic De-struction of Fulvic Acids by Oxygen in aTiO2 Suspension.” Journal of Water Chem-istry and Technology. 33(4), 236-247.

• Stevenson, F.J. (1994). Humus Chemistry:Genesis, Composition, Reactions. New York:John Wiley & Sons.

• Taylor J. S.; Snyder B. R.; Ciliax, B.; Ferraro,C.; Fisher, A.; Muller, P.; and Thompson, D.“Trihalomethane Precursor Removal by theMagnesium Carbonate Process,”EPA/600/S2-84/090, Water Engineering Re-search Laboratory, Cincinnati, Ohio, Sept.1984.

• Taylor J. S.; Thompson D.; Snyder B. R.; LessJ.; and Mulford L. “Cost and PerformanceEvaluation of In-Plant Trihalomethane Con-trol Techniques,” EPA/600/S2-85/138, WaterEngineering Research Laboratory, Cincin-nati, Ohio, Jan. 1986.

• Taylor, J.S.; Thompson, D.M.; and Carwell,J.K. (1987). Applying Membrane Processesto Groundwater Sources for TrihalomethanePrecursor Control. Journal AWWA, 79(8):72.

• Taylor, J.S.; Snyder, B.R.; Ciliax, B.; Ferraro,C.; Fisher, A.; Herr, J.; Muller, P.; andThompson, D. 1984. Project Summary: Tri-halomethane Precursor Removal by theMagnesium Carbonate Process. USEPA Re-search and Development. EPA-600/S2-84-090.

• Taylor, J.S.; Soyden, S.M.; Lyn, T.L.; and Mul-ford, L.A. (1992). Investigation and Analysisof Contaminants in the Potable Water Sup-ply of Pinellas County, Final Report on Dis-infectant Residual and Byproduct Modellingto Pinellas County, Florida. EnvironmentalSystems Engineering Institute, Civil and En-vironmental Department, University ofCentral Florida.

• Thompson, J.D.; White, M.C.; Harrington,G.W.; Singer, P.C. (1997). Enhanced Soften-ing: Factors Influencing DBP Precursor Re-moval. Journal AWWA, 89(6):94-105.

• Thomson, J.; Roddick, F.A.; Drikas, M.(2002). Natural organic matter removal byenhanced photo-oxidation using low pres-sure mercury vapour lamps. Water Sci. Tech-nol.: Water Supply, 2 (5–6), 435–443.

• Weiner J.M. (1995). Effects of Ozone on Tri-halomethane Formation: Pilot Plant Processand Kinetics. MS thesis. Amherst, Mass.:University of Massachusetts at Amherst.

• Yoon, Y.; Amy, G.; Cho, J.; and Her, N.(2005). Effects of retained natural organicmatter (NOM) on NOM rejection andmembrane flux decline with nanofiltrationand ultrafiltration. Desalination, 173: 209–221. ��



Kart Vaith and Lisa PrietoPresident and Vice President, FWEA

What is membership to you? What isit worth to you? What do you getout of your FWEA membership?

These are questions that we, as your FWEAleaders, have been asking ourselves. We con-stantly struggle with making sure that ourmembership is valuable to the FWEA com-munity. We want to make sure FWEA is fun,yet from a professional standpoint, fills avoid that many of our members don’t find in

their day-to-day jobs. For me it would behard to put a price on my experience atFWEA. My annual dues invoice is an after-thought to me because I feel I am muchmore than a member, and not just a cog inthe wheel of FWEA.

We were told by WEF staff in Augustthat dues are being raised $15, effective Jan.1, 2015, to accommodate the higher costs ofproviding services. This was no surprise, asthe annual inflation rate is about 1.7 percentand this is only the second dues increase overthe last decade. Because of the increasingcosts, coupled with providing members withmore services, including free webinars, dis-counted conferences, more specialty confer-ences, and an upgraded interactive website,we weren’t surprised to hear about the in-crease in dues.

Simultaneously, we at FWEA had beendebating the same idea. We have recently up-graded our website and have been providing

more elaborate registration and paymentservices for our events. In addition to the ris-ing costs at FWEA, we recognize that ourmembers are expected to do more with lessat work, so they have less time to volunteerfor the Association. We have also heard frommany of our members that the volunteers aregetting burned out and need more help.

We have recently done a major overhaulto the website and plan to continue to im-prove and update it. In addition, we haveprovided greater registration assistance toour chapters and committees through onlineregistration and credit card processing. Byproviding more assistance to our FWEAmembers, we can channel volunteer time tobe refocused to the more strategic needs ofFWEA. To provide additional help to ouroverworked volunteers, FWEA has decidedto increase dues by $20 annually.

Our goal is that, by providing more helpand assistance, our volunteers can focus onwhat is really important to them—whetherthat be helping to put together the technicalprogram for a seminar, working on the waterfestival, or writing an article for this maga-zine. We want volunteer time to be used inthe best way possible! And for those of youwho haven’t volunteered yet because it seemslike a daunting task, there will be more op-portunities to volunteer for smaller projectsthat are less overwhelming. We will also besending out a membership survey to makesure we are meeting your needs; please lookout for it and respond openly and honestlyto help us.

To reduce the burden on our membership,we are offering FWEA-only membership for our members as well. You can find more information on becoming a member or renewing your dues online athttp://www.fwea.org/how_to_join_renew.php.If you have any questions or comments, pleasedon’t hesitate to reach out to us at [email protected] or [email protected], or any ofyour FWEA leadership team. And as always,thank you for being a member–you are valu-able to the FWEA community! ��

The Meaning—and Worth—of Membership

FWEA FOCUS

VAITH PRIETO


Jeff Nash, P.E.CH2M HILL, Orlando

Work title and years of service.I am business development

director, American Water MarketPublic Sector, with 27 years ofservice in the industry.

What does your job entail?I am responsible for business

development for the public watersector for the United States, Canada,and Central and South America.The job involves helpingcommunities develop solutions forwater supply and water/wastewatertreatment and to complete neededprojects. I am also responsible forthe development of strategic plansfor targeting and pursuing newwater supply and water andwastewater treatment work,allocating the required resources forthese activities, and establishingmetrics for meeting firm goals.

What education and traininghave you had?

I have a B.S. in chemicalengineering and an M.S. inenvironmental engineering fromVirginia Tech. I finished a shortcourse at the Michigan BusinessSchool and have taken various sales,financial, and project managementcourses.

What do you like best about yourjob?

There are several things: theopportunity to work on programsand projects throughout the UnitedStates and internationally; knowingthat my efforts can have a positive

impact on the communities weserve and my company’s success; thechance to work with outstandingprofessionals throughout ourindustry; and the opportunity toparticipate in professional societiesthat promote the water industry andcharitable causes.

What organizations do youbelong to?AWWA, WEF, Water For People, andLeadership Florida.

How have the organizationshelped your career?

They have been an immensehelp. Every individual in our fieldshould be a member and activeparticipant in a professionalorganization. It can provide theopportunity to developrelationships with fellowprofessionals, share technologysolutions, and accomplishsignificant charitable works.

What do you like best about theindustry?

What I like most is that weprovide a service of significantimportance to society. Clean waterand sanitation are two of the mostbasic human needs. Everyone in ourindustry should be proud of whatthey do and the service they provideto their clients and communities.Furthermore, the professionals inour industry are good-heartedpeople who are great to associateand work with. In addition to theirwork responsibilities, they areextremely generous with their timeand money for charitable causes,including providing educationalscholarships and assisting in projectsto provide clean water for needycommunities around the world.

What do you do when you’re notworking?

When not traveling as part ofmy job, I stay close to home with myfamily. We grill or smoke somethingfor friends most weekends. I alsogrew up working at a golf courseand like to play the game. Myvolunteer time is primarily focusedon AWWA activities. ��


FWRJ READER PROFILE The Barracuda Class dredge from DSC Dredge features a

swinging-ladder design and is easily transportable, making it idealfor navigational, recreational, or restorative projects such as waterwaymaintenance and lake revitalization. With the option of two front-swing winches, the dredge can convert from a swing ladder to a con-ventional one without sacrificing portability. (www.dscdredge.com)

�The horizontal sludge-dewatering from In The Round De-

watering has a stainless steel drum with perforated plastic tile lin-ing. The drum is mounted on a roll-off frame for easytransportation and unloading. Water trays allow for containmentof discharge water. An 18,000- to 25,000-gal batch is mixed withpolymer before bring filtered in the rotating drum, driven by a ½hp variable-speed electric motor with a heavy-duty chain andsprocket. The turning eliminates crusting and wet pockets, pro-ducing uniform, consistent results. The dewatering material dumpseasily, the drum is self-cleaning, and dewatering can be completedin one night. (www.itrdewatering.com)

�The InstoMix high-energy flash mixer from Walker Process

Equipment disperses coagulant and other flocculent solutions intoraw water and wastewater. The flash blending of coagulant results inoptimum floc formation and maximizes chemical company. Thecompact in-line units are constructed for flange mounting directly inthe pipeline and are equipped with an internal-feed manifold de-signed to distribute solutions uniformly throughout the sectionalizedmixer body. The design allows low-energy input, low headloss, andhigh G-Value results. The agitator can be custom-sized to produce adesired G-Value. Units are available for 8- to 72-in. pipelines.(www.walker-process.com)

�Defender Tank Covers from Environetics Inc. are custom

manufactured from industrial grade materials to fit the profile ofnew or existing wastewater treatment tanks or portable water tanks.Odorous gas emissions from wastewater facilities generate com-plaints from local residents and are subject to the Clean Air ActAmendments of 1990. Defender odor control covers containvolatile organic compounds at the source. Low-profile structurallysupported covers minimize emission treatment volume to reducethe cost of air filtration equipment, eliminating the ongoing ex-pense of applying costly odor control chemicals through atomizerand misters. (www.environetisinc.com)

�The TLT Series stand-alone primary tank-mounted screen

from IPEC Consultants can be used for truck receiving andpumped sanitary wastewater applications. Components include atank, shaftless screw, screen basket, transport tube, press zone, anddischarge section. There are two automatic showers, one inside thetank and one in the press zone and upper transport zone. Influententers the upstream end of the tank where coarse solids are retainedon the surface of the screen basket. The shaftless screw brushes cap-tured solids from the screen surface up the transport section to apress zone, where a plug is formed. Solids are dewatered by com-paction against the plug, and liquid is discharged through a shortscreen section. The press zone shower washes fine, loose solids backinto the channel. Compact solids with dryness of 40 percent ormore are scraped from the plug and discharged. (www.ipec.com)��

New Products

From page 20

1. C) Surface contact between the air andwater.The efficiency of the aeration process is affectedmostly by the amount of surface contact between theair and water. This contact is controlled primarily bythe size of the water drop or air bubble. This is whymany operators have tried different media toincrease turbulence (contact between water and air)in an effort to increase efficiency. The same conceptis at play in packed tower aeration units, increasingsurface contact between water and air.

2. A) Increased pHPhotosynthesis by algae reduces carbon dioxide inthe water; as the carbon dioxide is reduced, the pHwill increase. This occurs mainly during the day; atnight, respiration by algae will increase the carbondioxide in the water and lower the pH. Changes inpH levels will impact the treatment process,including coagulation and disinfection.

3. B) Control water velocity as it entersthe basinThe other primary purpose of the inlet zone is tostart slowing down the water velocity. This is thereason for baffling the tank. Remember, thesedimentation zone is really a settling zone, so thewater has to slow down for gravity to work; if not,the formed clumps (floc) of suspended solids will becarried through the tank and onto the filters.

4. A) Turbidity into and out of the tankTurbidity readings are essential not only in thesedimentation process, but throughout the treatmentprocess from source water to postfiltration. In thesedimentation basin, comparing the turbidity ofwater entering and leaving the basin will give theoperator a good idea of the removal efficiency of theprocess. Increases in the inlet may indicate changesin source water turbidity or chemical feed problems.In the tank outlet, increased turbidity could indicatea high sludge blanket or a hydraulic overload.Turbidity is one of the essential process control testsfor an operator using coagulation.

5. D) Flash mix Flash mixing is the process used to disperse andinitially mix coagulant chemicals with water. Theentire process occurs in only a few seconds. All theother answers were types of mixers used in the flashmix process.

6. A) 5 to 7Lower pH levels favor the formation of positivelycharged particles that will react with the negativelycharged nonsettleable particles, causing them toclump together and become heavier and settle out ofthe water.

7. B) Galvanic corrosion Galvanic corrosion occurs when one metal gives upelectrons to a dissimilar metal. Metals are listed in thegalvanic series as to their resistance to give upelectrons (corrode). One such metal is gold; it does noteasily give up electrons and it does not corrode. Metals

that do not give up electrons are cathodes and thosethat do give up electrons are anodes. Other metals,such as zinc, easily give up electrons (anodes) and areconsidered base metals. One way to avoid galvaniccorrosion is to install a dielectric fitting (plastic) inbetween the two dissimilar metals, which will stop theflow of electrons and stop corrosion from occurring.

8. D) They are a stronger disinfectantthan chlorineChloramines are weaker than chlorine, but are morestable. Their stability allows the disinfectantproperties to last longer and penetrate biofilm.Chlorine is a stronger disinfectant and very reactive,so over time in the distribution system, all thedisinfectant ability may be used up and not beavailable for use in penetrating biofilm.

9. A) Water hammerWater hammer is caused when fluid in motion—inthis case, water—has sudden changes in velocity.The kinetic energy associated with the velocitycreates a shock wave of pressure. Increases in pressurerelated to the sudden stopping of water flow canresult in pressure increases of 200 to 400 pounds persq in. (psi).

10. A) Granular activated carbonGranular activated carbon made from heatingcarbon, such as wood, has high adsorptive propertiesthat allow it to remove tastes and odors fromdrinking water. The adsorptive properties ofactivated carbon do not last indefinitely and thespent carbon must be regenerated or replaced.

Certification Boulevard Answer Key


PS Form 3526: Statement of Ownership, Management and Circulation(Required by 39 U.S.C. 3685)

(1) Publication Title: Florida Water Resources Journal. (2) Publication Number 0896-1794. (3) Filing Date: 09/30/14. (4) Issue Frequency: Monthly. (5) No. of Issues PublishedAnnually: 12. (6) Annual Subscription Price: $6/members, $24/non-members. (7) Complete Mailing Address of Known Office of Publication: 1402 Emerald Lakes Dr., Clermont,FL 34711. Contact Person: Michael Delaney. Telephone: 352-241-6006. (8) Complete Mailing address of Headquarters or General Business Office: 1402 Emerald Lakes Dr., Cler-mont, FL 34711. (9) Publisher: Florida Water Resources Journal, Inc. 1402 Emerald Lakes Dr., Clermont, FL 34711. Editor: Rick Harmon, 1402 Emerald Lakes Dr., Clermont, FL34711. Managing Editor: Michael Delaney, 1402 Emerald Lakes Dr., Clermont, FL 34711(10) Owner: Florida Water Resources Journal, Inc. 1402 Emerald Lakes Dr., Clermont,FL 34711. Stockholders: (33 1/3% each) Florida Water and Pollution Control Operators Association, P.O. Box 109602, Palm Beach Gardens, FL 33410-9602; Florida Sec-tion/American Water Works Association, 769 Allendale Rd., Key Biscayne, FL 33149; Florida Water Environment Association, 4350 W. Cypress St. #600, Tampa, FL 33607. (11)Known Bondholders, Mortgages, and Other Security Holders Owning or Holding 1 Percent or More of Total Amount of Bonds, Mortgages, or Other Securities: None. (12) The pur-pose, function, and nonprofit status of this organization and the exempt status of federal income tax purposes: Has not changed during preceding 12 months. (13) Publication Name:Florida Water Resources Journal. (14) Issue Date for Circulation Data Below: October 2014.

(16) This Statement of Ownership will be printed in the November 2013 issue of this publication. (17) Signature and Title Editor, Publisher, Business Manager, or Owner. I certify thatall information furnished on this form is true and complete: I understand that anyone who furnishes false or misleading information on this form or who omits material or informationrequested on the form may be subject to criminal sanctions (including fines and imprisonment) and/or civil sanctions (including multiple damages and civil penalties). Date: 9/30/14

Actual No. Copies ofSingle Issue PublishedNearest to Filing Date

7,2000

7,121

7,12100

7,12179

7,20098.90%

(15) Extent and Nature of Circulation

a. Total No. of Copies (Net Press Run)b. Paid and/or Requested Circulation

(1) Sales through dealers and carriers, street vendors and counter sales (not mailed)(2) Paid or requested Mail Subscriptions (Include advertisers proof copies/exchange copies)

c. Total Paid and/or Requested Circulation (Sum of 15b(1) and 15b(2)d. Free distribution by Mail (Samples, complimentary, and other free)e. Free Distribution Outside the Mail (carriers or other means)f. Total Distribution (Sum of 15c and 15f)g. Copies Not Distributedh. Total (Sum of 15g and 15g)i. Percent Paid and/or Requested Circulation (15c/15gx100)

Average No. CopiesEach Issue During

Preceding 12 Months

7,190

0

7,112

7,11200

7,112

787,190

98.92%


The team from the University of SouthFlorida was a winner in the 2014 Water En-vironment Federation (WEF) Student De-sign Competition, which took place in earlyOctober in New Orleans. The team’s proj-ect, “South/Central Hillsborough CountyService Area Capital Improvements Proj-ect,” won in the wastewater design category.

A program of WEF’s Students andYoung Professionals Committee, the com-petition promotes real-world design expe-rience for students interested in pursuingan education and/or career in water/waste-water engineering and sciences. The contesttasks individuals or teams of studentswithin a WEF student chapter to preparedesigns to help solve a local water qualityissue. The projects perform calculations,evaluate alternatives, and recommend themost practical solutions based on experi-ence, economics, and feasibility.

Members of the University of SouthFlorida team were: Lauren Davis, MichaelEsteban, Jared Faniel, Andrew Filippi, Win-

some Jackson, Herby Jean, Richard John-son, and the faculty advisor, Dr. SarinaErgas.

Florida Team Wins WEF Student Design Competition

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ENGINEERING DIRECTORY

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EQUIPMENT & SERVICES DIRECTORY

Contact Mike Delaney at 352-241-6006



CentralFloridaControls,Inc.

Instrumentation Calibration

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On-Site Water Meter Calibrations

Preventive Maintenance Contracts

Emergency and On Call Services

Installation and System Start-up

Lift Station Controls Service and Repair

Instrumentation,Controls Specialists

Florida Certified in water meter testing and repair

P.O. Box 6121 • Ocala, FL 34432Phone: 352-347-6075 • Fax: 352-347-0933

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CEC Motor & Utility Services, LLC1751 12th Street EastPalmetto, FL. 34221

Phone - 941-845-1030Fax – 941-845-1049

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• Motor & Pump Services Test Loaded up to 4000HP, 4160-Volts

• Premier Distributor for Worldwide Hyundai Motors up to 35,000HP

• Specialists in rebuilding motors, pumps, blowers, & drives

• UL 508A Panel Shop, engineer/design/build/install/commission

• Lift Station Rehabilitation Services, GC License # CGC1520078

• Predictive Maintenance Services, vibration, IR, oil sampling

• Authorized Sales & Service for Aurora Vertical Hollow Shaft Motors

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Posi t ions Avai lable

Water Systems Optimization (WSO)is seeking a graduate Civil Engineer with 3 to 5 years of water distribu-tion system experience. The position will require permanent relocationto Nashville, TN. Interested parties can inquire by e-mail to Paul John-son at [email protected].

Utilities Storm Water Supervisor$53,039-$74,630/yr. Plans/directs the maintenance, construction, re-pair/tracking of stormwater infrastructure. AS in Management, Envi-ronmental studies, or related req. Min. five years’ exp. in stormwateroperations or systems. FWPCOA “A” Cert. pref.

Asset Management/Project Specialist$50,514-$71,077/yr. Implements and maintains the Utility’s Asset Mgmt& Maint. database. BS degree with major coursework in Computer Sci-ence, IT or Communications.

Utilities Treatment Plant Operations Supervisor$53,039 - $74,631/yr. Assists in the admin & technical work in the mgmt,ops, & maint of the treatment plants. Class “A” Water lic. & a class “C”Wastewater lic. req. with 5 yrs supervisory exp.

Utilities Treatment Plant Will Call Operator$17.93-$27.82/hour. Part time. Must have passed the C drinking wateror wastewater exam.Apply: 100 W. Atlantic Blvd., Pompano Beach, FL 33060. Open untilfilled. E/O/E. http://pompanobeachfl.gov for details.

Purchase Private Utilities and Operating RoutesFlorida Corporation is interested in expanding it’s market in Florida.We would like you and your company to join us. We will buy or part-ner for your utility or operations business. Call Carl Smith at 727-835-9522. E-mail: [email protected]

We are currently accepting employment applicationsfor the following positions:

Water & Wastewater Licensed Operator’s – positions are available inthe following counties: Pasco, Polk, Highlands, Lee, Marathon

Maintenance Technicians – positions are available in the following locations: Jacksonville, New Port Richey, Fort Myers,

Lake, Marion, Ocala, Pembroke Pines

Construction Manager – Hillsborough

Customer Service Manager - Pasco

Employment is available for F/T, P/T and Subcontract opportunitiesPlease visit our website at www.uswatercorp.com

(Employment application is available in our website)4939 Cross Bayou Blvd.

New Port Richey, FL 34652Toll Free: 1-866-753-8292

Fax: (727) 848-7701E-Mail: [email protected]

Water and Wastewater Utility Operations, Maintenance, Engineering, Management

City of Coconut Creek, FL:Utility Service Worker II (Water)

Utilities & Engineering DepartmentSalary: $15.38/hour; $31,990.40 Annually

High school diploma or GED; supplemented by up a minimum of two(2) years’ experience in water distribution; an equivalent combination ofeducation, certification, training, and / or experience may be consid-ered. Must have a valid Florida commercial driver's license, Class B orhigher; Florida Water Pollution Control Operators Association (FWP-COA) Class “C” Water Distribution certification; and Department ofEnvironmental Protection (DEP) Class III license. ASSE Backflow Cer-tification; Confined Space certification; CPR certification; and interme-diate level Maintenance of Traffic (MOT) certifications are preferred,and must be obtained within one (1) year of hire. Apply online atwww.coconutcreek.net

C L A S S I F I E D S



City of Vero BeachElectronics Technician

Services, maintains, installs and performs preventative maintenance ofelectronic and electrical equipment throughout the water and sewer sys-tem. Must have thorough working knowledge of configuring, program-ming and maintenance of Modicon Programmable Logic Controllersand GE IFix HMI software version 5.5 and later. Visit website for com-plete job description, qualifications needed, and instruction to apply.$28.04 p/hr www.covb.org City of Vero Beach EOE/DFWP 772 978-4909

City of Tampa Wastewater Department –Wastewater Operations Manager

The City of Tampa is seeking a Wastewater Operations Manager to di-rect the operation of the municipal wastewater collection and trans-mission system. Suggested Minimum Requirements: Education: Bachelor’s degree in engineering, public utilities or environ-mental scienceExperience: Five (5) years’ experience in wastewater collection/trans-mission systems with two (2) years’ of manager or supervisor capacity,or equivalent combination of training and experience.License: Valid driver’s license; “A” license in Wastewater Collection withinone (1) of employmentFor more information, please go to the City of Tampa employment web-site http://www.tampagov.net/employment-services

Booth, Ern, Straughan & Hiott, Inc.Utility Design Engineer

BESH Engineering seeks experienced utility design engineer for all as-pects of water and wastewater design, including treatment plants, pumpstations, and collection/transmission/distribution systems. Applicantmust have water and wastewater treatment plant design and permittingexperience. Experience with hydraulic modeling, specification writing,Autocad drafting, project bidding, construction oversight and projectfunding preferred. Applicant must possess State of Florida E.I. with min-imum 4 years experience. Florida P.E. a plus. Salary commensurate withexperience. Come join a great team! Drug Free Workplace and an EqualOpportunity Employer. Please email resume to: [email protected]

Deputy Director of UtilitiesMartin County Board of County Commissioners is seeking a DeputyDirector of Utilities who will assist in the long range planning for newwater supply sources and facilities, provide professional administrativeoversight for the County's water & wastewater operations, and coordi-nate with governmental agencies, engineers and financial staff to assurethe most cost effective systems.

The ideal candidate will hold a P.E., a bachelor's degree in Civil Engi-neering and have 8 years of experience in water or public utilities field.

Please visit www.martin.fl.us and click on the Jobs board for additionalinformation regarding this position.


Editorial Calendar

January . . . . . .Wastewater Treatment

February . . . . .Water Supply; Alternative Sources

March . . . . . . .Energy Efficiency; Environmental Stewardship

April . . . . . . . .Conservation and Reuse; Florida Water Resources Conference

May . . . . . . . . .Operations and Utilities Management

June . . . . . . . .Biosolids Management and Bioenergy Production; FWRC Review

July . . . . . . . . .Stormwater Management; Emerging Technologies

August . . . . . .Disinfection; Water Quality

September . . .Emerging Issues; Water Resources Management

October . . . . . .New Facilities, Expansions, and Upgrades

November . . . .Water Treatment

December . . . .Distribution and Collection

Technical articles are usually scheduled several months in advance and are due 60 daysbefore the issue month (for example, January 1 for the March issue).

The closing date for display ad and directory card reservations, notices, announcements,upcoming events, and everything else including classified ads, is 30 days before the issuemonth (for example, September 1 for the October issue).

For further information on submittal requirements, guidelines for writers, advertising ratesand conditions, and ad dimensions, as well as the most recent notices, announcements, andclassified advertisements, go to www.fwrj.com or call 352-241-6006.

KLJEngineer III - Water System Engineer

Are you looking for a stable career with a flexible firm that encouragesthinking outside the box? Join a nationally-recognized company thatnot only survived the last recession, but thrived with exponential growth.KLJ is a multi-disciplinary engineering firm looking for an experiencedwater system engineer to join our Billings, Montana office location. Ifyou enjoy fishing, camping and skiing in one of the nation’s most cov-eted environments, look no further. Excellent communication skills, de-sign team experience and a current PE is required. We are anemployee-owned company who offers competitive compensation andbenefits, 401k, profit sharing retirement program and an environmentfor personal and professional growth. Apply online today at kljeng.com.

Water and Wastewater Treatment Plant OperatorsThe City of Edgewater is accepting applications for a Water and a Waste-water Treatment Plant Operator, minimum Class C license required.Valid FL driver license required. Annual Salary Range is $31,096 -$48,755. Applicants will be required to pass a physical and backgroundcheck. Applications and information may be obtained from the Person-nel Dept or www.cityofedgewater.org, and submitted to City Hall, 104N Riverside Dr, Edgewater, FL 32l32. EOE/DFWP

Posi t ions WantedDONALD GAVON – Holds Florida B Wastewater and C Water licenses with 32 yearsexperience and has extensive knowledge in all facets of the water and wastewater in-dustry. Prefers central Florida but will consider other areas. Contact at 4204 MackerelDr., Sebring, Fl. 33870. 863-446-1678

MARK McQUAIG – Holds a Florida Double B license with 15 years experience in-cluding an excellent electrical background and knowledge of nutrient removals.Prefers the northwest to panhandle area. Contact at 236 Perdue Road, DeFuniakSprings, Fl. 32433. 850-449-9239

KIRK SHAFER – Holds a Florida A Water license with seven years experience andprefers the Naples and adjacent areas but is willing to relocate. Contact at 990 PartridgeCircle, Unit #102, Naples, Fl. 34104. 239-435-1940

BILL YOCUM – Holds Florida A Wastewater and B Water licenses. Seeking a posi-tion in consulting or contract operation work. Will be retiring in January 2015 and willbe available for employment February 1st. Contact at 352-342-2781 or [email protected]

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American Ductile..................................51

CEU Challenge......................................45

Crom....................................................43

Data Flow ............................................33

FSAWWA Conference ......................15-19

FWPCOA Training ................................41

Garney .................................................5

GML Coating ..................................31, 57

HDR Engineering Inc ......................22-23

Hudson Pump ......................................37

Polston Technology ..............................53

Professional Piping ..............................27

Quality Control ....................................54

Reiss Engineering ..................................7

Severn Trent ........................................62

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USA Blue Book ......................................9

US Water ...............................................8

Xylem...................................................64

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Looking For a Job? The FWPCOA Job Placement Committee Can Help!

Contact Joan E. Stokes at 407-293-9465 or fax 407-293-9943 for more information.

Documents

Florida Water Resources Journal - November 2014