Curtis D. Courter, P.E. - Ohio Water Environment Association · Physical-Chemical Clarification ... Common Elements Feeder / hopper Mix tank Mixers Shear mill and magnetic separator

2011 OWEA Wet Weather Issues Webinar Series

Curtis D. Courter, P.E.

Webinar Topics

Background

Treatment Alternatives

Solids and Floatables Control

Disinfection Alternatives

Clarification

○ EHRT

○ HRPCT

Background - CSOs

Discharge untreated sewage diluted with

rainwater to local waterways (CSO)

Water quality & human health impacts

National issue

85 Ohio communities

w/ combined systems

Over 1300 CSOs

Source: City of Wilmington Delaware

Background – Water Quality

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20

40

60

80

100

120

140

160

Str

ea

m/R

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r M

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s (

10

00

s)

Source: iaspub.epa.gov

Background - Regulatory

CSO Control Policy

Clear levels of control

Flexibility

Phased implementation

Review and revision WQS

Nine Minimum Controls

NPDES Permits

Consent Judgments

Webinar Topics

Background




Clarification

○ EHRT

○ HRPCT

Why Solids and Floatables

Control? Nine Minimum Controls

Control of solids & floatables materials in CSOs (NMC 6)

Pollution prevention to reduce contaminants in CSOs (NMC 7)

Narrative Water Quality Standards

Waters shall be free from floating materials entering as result of human activity in amounts to be unsightly or cause degradation – OAC 3745-1-04B

Pollution Discharge Elimination Permits

None as a result of discharge in unnatural quantities injurious to designated use - MI0022802

Consent Orders

Engineering study of past , current and future measures to control solids and floatables materials – Cincinnati MSD

Assess construction of facilities for removing floatables from CSOs as an element of LTCP – Toledo

Solids and Floatables Controls

Source controls

In-System controls

End-of-Pipe controls

Source Controls

Pollution prevention

Source Controls

Catch basin modifications

Source Controls

Filters

In-System & End-of-Pipe Controls

Simple bar racks


Static baffles


Dynamic baffles


Mechanically cleaned screens


Proprietary controls

Hydrodynamic separators

Nutrient Separating Baffle Box

Others

End-of-Pipe Controls

Nets


In Receiving Water - Nets


In Receiving Water - Booms

Case Study - Sanitation District

No. 1

SD1 Program Options

Regulatory:

○ S&F Controls everywhere

Other Communities:

○ Pilot engineered controls

Hybrid:

○ Simple S&F w/ engineered controls

Pilot program developed

Hydraulic criteria, controls, inspection forms

Cincinnati

Simple S&F Controls – Bar Racks

& Baffles

Dry Weather Flow

Sump Outfall

Pleasant Street

4th Street Baffle

Weir

Outfall

Simple S&F Controls – Net Bags

Net Bags

Elevated Outfall Pipe

Engineered S&F Control

Baffle

Outfall

NSBB

Screen

Sediment Sumps

Sewer

Select Observations – Bar Racks

Natural Debris

Influent Outfall

Blocking

Rack Overtopping

Influent

Outfall

Blocking Tie-off

Overtopping ~ 6 month storm event

Select Observations – Baffles

Baffle

Outfall Influent

Baffle Overtopping

Outfall

Blocking Tie-off

Influent

Overtopping ~ 6 month storm event

Select Observations – Nets (Logged

Changes) Mary Ingles

5 lbs (12/4/07)

6 lbs (12/5/07)

1½ lbs (12/11/07)

8 lbs (12/26/07)

5 lbs (6/19/08) 4 lbs

5 lbs 8 lbs

Pilot S&F Control Pilot Program

Summary of findings:

Bar racks ineffective due to blinding and height

limitations due to hydraulic restrictions

Weirs and baffles marginally effective – need good

hydraulics at CSO diversion (check velocity under

baffle)

Nets on elevated overflow outfall pipes highly

effective as long as velocities are not too high

(damage nets)

Final S&F Control Program

Install simple controls (weirs/baffles and nets) where configuration and hydraulics allow and effectiveness anticipated

Engineered control locations would be through watershed planning

Source controls – public education, street cleaning, catch basin modifications & cleaning, grit pits, regulate construction site runoff

Webinar Topics

Background




Clarification

○ EHRT

○ HRPCT

Effect on Cl2 Dose in Regression Models

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1 10 100 1,000 10,000 100,000 1,000,000

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oli

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4 mg/l - Cl2

8 mg/l - Cl2

10 mg/l - Cl2

20 mg/l - Cl2 Spring

Crk. (1997)

6 mg/l - Cl2

D.T. = 4 minutes

TKN = 3.6 mg/l

BOD = 31.5 mg/l

Source: Combined Sewer Overflow Abatement Program, Rochester, NY Volume II.

Pilot Plant Evaluations (EPA 600/2-79-031b)

Effect on Cl2 Dose in Regression Models

0

1

2

3

4

5

1 10 100 1,000 10,000 100,000 1,000,000

GT

Lo

g F

. C

oli

. R

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uct

ion

4 mg/l - Cl2

8 mg/l - Cl2

10 mg/l - Cl2

20 mg/l - Cl2 Spring

Crk. (1997)

6 mg/l - Cl2

D.T. = 4 minutes

TKN = 3.6 mg/l

BOD = 31.5 mg/l

Source: Combined Sewer Overflow Abatement Program, Rochester, NY Volume II.

Pilot Plant Evaluations (EPA 600/2-79-031b)

High Rate Disinfection

Application of disinfectants using high-rate

mixing as a substitute for contact time

Kill = C x G x T

Where: T ≤ 5 minutes

Applies to chemical

disinfectants

Disinfection Methods

Ozone

Chlorine Dioxide

Gaseous Chlorine

Calcium Hypochlorite

UV

Sodium Hypochlorite

Peracetic Acid

BCDMH (bromine)


Ultra Violet (UV)

Physical disinfectant

Common Elements

Pretreatment

Power center

Lamps

Ballast

Cleaning System

Gates (level control & Isolation)

Instrumentation (transmittance, etc.)


Sodium Hypochlorite (NaOCl)

Chlorine based solution

Common Elements

Storage tanks

Transfer pumps

Day tanks

Feed pumps

Mixers / diffusers

Instrumentation (flow, TRC, ORP, TSS)

Sampling equipment

Dechlorination


Peracetic Acid (PAA)

Acetic Acid and Hydrogen Peroxide solution

Common Elements

275 gallon totes or 55 gallon drums

Feed pumps

Mixers / diffusers

Instrumentation (flow, TSS)

Sampling equipment

Pressure relief

Heat monitoring


Bromochlorodimethylhydantoin (BCDMH)

Bromine based powder

Common Elements

BCDMH Unit ○ Storage hopper

○ Feed equipment

○ Dissolution equipment

Feed pumps

Mixers / diffusers

Instrumentation (flow, TSS)

Sampling equipment Courtesy of City of Akron

Case Study – Conner Creek

Retention Treatment Basin

NPDES Permit Requirements

5 minute detention time @ 10-Yr peak flow

○ 30 MG @ 13,262 CFS

Fecal coliform limits

○ 400 cfu/100 ml daily

○ 200 cfu/100 ml monthly

TRC goal < 1 mg/L

Disinfection System Studies

Disinfection Pilot Study

Mixer Modeling

NaOCl

Degradation

Study

NaOCl Feed System

Control Study


Objectives

Determine dose vs. kill relationship

Determine effect of mixing technology on kill

Disinfectant

Sodium hypochlorite

Technologies Tested

Vertical shaft

Pumped diffusion

High speed submersible induction

G ~ 500 sec-1


Conclusions

Mixing technology:

○ Mixers are equivalent for equivalent G

○ Rapid and thorough mixing is critical

CxT = 125

○ ≥ 4 log fecal coliform reduction

○ ≤ 400 cfu/100 ml

Submersible induction mixers selected

Mixer Modeling

High speed submersible mixers

Between 4 and 8 mixers required per channel

Objectives

Determine the number of mixers

3 Mixers Tested

2 Manufacturers, vacuum and non-vacuum styles

Rhodamine WT tracer

Mixer Modeling

Conte Anadromous Fish Research Center

Testing

Channel

Mixer Modeling Sampling Station 1

10 Feet Downstream of

Mixer

Sampling Station 2

58 Feet Downstream of

Mixer Sample

Pumps

Sampling

Grid

Mixer Modeling

0.25 Normalized Cl2 Contours

Measured 10 Feet Downstream

of Mixer At 3.2 FPS

Mixer Modeling

0.1 Normalized Cl2 Contours Measured 58

Feet Downstream of Mixer At 2.7 FPS

Mixer Modeling

Conclusions

Secondary Mixing Enhances Dispersion

Six Mixers Per Channel

Additional Disinfectant Needed At Bottom

of Channel

Contact Basin Starts Approx. 58-Feet

Downstream of Mixers

Operational Observations From 2-

Year Intensive Monitoring*

46 activations & 25 discharge events

Captured 2.5 billion gallons and

discharged another 2.9 billion gallons of

treated effluent

Max effluent flow ~2,600 cfs (T~25 min.)

Over 13-1/2 days of overflow

Recently had an event lasting 8 days

*DWSD 2008, Conner Creek CSO Basin Evaluation, October 24, 2008.

Webinar Topics

Background




Clarification

○ EHRT

○ HRPCT

High Rate Clarification

Alternatives

Chemical (non-proprietary)

CEPT

EHRT

Physical-Chemical (proprietary)

CoMag / BioMag

Densadeg

Actiflo / Bio-Actiflo

Windsor Ontario EHRT Pilot Plant

Chemically Enhanced

Clarification CEPT / EHRT

Addition of coagulant and polymer

Aggregates particles (flocculation)

Common Elements

Screens

Grit chamber

Settling tank

Chemical feed system

Mixers

Baffles

Instrumentation, pumps, piping, etc.

Physical-Chemical Clarification

Densadeg

Degremont Technologies

Recycled sludge ballast

Polymer

Common Elements

Screens

Reactor

Rapid Mixer

Lamella tubes



Actiflo / Bio-Actiflo

Microsand ballast

Polymer

Common Elements

Fine screens

Hydrocyclones

Rapid Mixer

Lamella plates

Instrument., pumps, piping, etc.


CoMag / BioMag

Cambridge Water Tech.

Magnetite ballast

Polymer

Common Elements

Feeder / hopper

Mix tank

Mixers

Shear mill and magnetic separator

Ballast make up


Case Study – NYCDEP Jamaica

Tribs CSO Project

NYC Actiflo & Densadeg side-by-side

pilot

Unit No. of

Runs

Flow

(mgd)

HRT

(min)

FeCl3

(mg/L)

Polymer

(mg/L)

SOR (1000s -

gpd/ft2)

Startup

Time (min)

Densadeg 17 0.2-0.5 12-33 50-70 1.4-1.8 29-65 30-60

Actiflo 15 0.3-0.8 5-11 60-100 0.45-1.0 72-130 5-10

Unit Waste

Sludge

TSS (%)

Influent

TSS

(mg/L)

Effluent

TSS

(mg/L)

TSS

Removal

(%)

Influent

BOD5

(mg/L)

Effluent

BOD5

(mg/L)

BOD5

removal

(%)

Densadeg 1-10% 83 25 69% 151 63 58%

Actiflo 0.1-0.3% 106 16 84% 119 51 57%

Questions?

Thank You Curtis D. Courter, P.E.

Hazen and Sawyer, P.C.

[email protected]

www.hazenandsawyer.com

(513) 469-5115 – Office

(513) 833-5125 - Mobile

mailto:[email protected]

http://www.hazenandsawyer.com/

Documents

Curtis D. Courter, P.E. - Ohio Water Environment Association · Physical-Chemical Clarification ... Common Elements Feeder / hopper Mix tank Mixers Shear mill and magnetic separator