Evaluation of Water Quality Management Alternatives to Control Dissolved Oxygen and Un-ionized Ammonia for Ravi River in Pakistan

Evaluation of Water Quality Management Alternativesto Control Dissolved Oxygen and Un-ionized Ammoniafor Ravi River in Pakistan

Husnain Haider & Waris Ali

Received: 28 February 2011 /Accepted: 12 December 2012 /Published online: 30 December 2012# Springer Science+Business Media Dordrecht 2012

Abstract Different water quality management alternatives,including conventional wastewater treatment, transportationof wastewater, flow augmentation, low-cost treatment withreuse, and wetlands, are evaluated by using a verified dis-solved oxygen (DO) model for the Ravi River. Biokineticrate coefficients of the Ravi River for both the carbonaceousand nitrogenous oxygen-demanding wastes are adjusted,keeping in view the type and level of wastewater treatment.The conventional activated sludge process with nitrificationcomes out to be the most expansive alternative to meet theDO standard of 4 mg/L. Additional treatment cost is re-quired to maintain un-ionized ammonia levels <0.02 mg/L,which corresponds to achieving treatment levels of 5 mg/Lof DO in the river. Under critical low-flow conditions (i.e.,minimum average seven consecutive days) of 9.2 m3/s, aflow augmentation of 10 m3/s can reduce 30 % of the costwith conventional wastewater treatment. Transportation ofwastewater from the city of Lahore is a cost-effective alter-native with 2.5 times less cost than the conventional pro-cess. Waste stabilization ponds (WSP) technology is a low-cost solution with 3.5 times less cost as compared to theconventional process. Further reduction in pollution loads tothe Ravi River can be achieved by reusing WSP effluents forirrigation in the near proximity of Lahore along the RaviRiver. The study results show that, for highly polluted riverswith such extreme flow variations as in case of the RaviRiver, meeting un-ionized ammonia standards can reduce

the efforts required to develop carbonaceous biochemicaloxygen demand-based waste load allocations.

Keywords Dissolved oxygen . Biochemical oxygendemand .Water quality management . Dissolved oxygenmodeling . Un-ionized ammonia .Water quality control

1 Introduction

Freshwater bodies in developing countries are being pollut-ed due to discharge of untreated wastewaters both fromdomestic and industrial sources. Moreover, in a number ofsituations, the stream water quality standards are beingviolated even though the effluent quality standards are metdue to low available dilutions in the receiving water body.To overcome these issues, water quality management(WQM) of the rivers (based on the optimum level of waste-water treatment) should be done by using the calibrated andverified water quality models, keeping in view the best useof the water body [1].

WQM of a specific river receiving wastewater fromdomestic and industrial sources can be done by adoptingdifferent waste control alternatives. These alternatives aredifferent from each other not only in terms of initial andoperational costs but also produce effluents with specificwastewater characteristics (e.g., nitrogen), depending on thetype of treatment used. Moreover, the effluents treated atdifferent levels of wastewater treatment have varying effectson the biokinetics of the river system and thus produceexplicit impact on the dissolved oxygen (DO) profile inthe river [2]. The evaluation of these WQM alternativesshould be done on the basis of cost, keeping in view thecompliance of the designated water use of the river system.Most of the recent WQM studies are either based on thedevelopment of new computational techniques or use ofrecently developed computer software without considering

H. Haider (*)School of Engineering, University of British Columbia Okanagan,3333 University Way,Kelowna, BC, Canada V1V 1V7e-mail: [email protected]

W. AliInstitute of Environmental Engineering and Research, Universityof Engineering and Technology, Lahore, Pakistan 54890e-mail: [email protected]

Environ Model Assess (2013) 18:451–469DOI 10.1007/s10666-012-9353-z

the changes in biokinetics with level of treatment [3–7].Such WQM studies may lead to a higher level of treatmentthan the required and thus resulting in higher costs. Thesituation may become more critical for the river systemsreceiving high pollution loads under low-flow conditions(i.e., minimum average seven consecutive days flow[MA7CD]). Such rivers require very high waste removalefficiencies to meet specific DO standards. In such rivers, ifthe appropriate biokinetics rates are not considered withchange in level of treatment, the cost of the selected alter-ative can be very high [1].

Ravi River is one of the five major rivers in Pakistan andis the most polluted due to high pollution loads from the cityof Lahore which find their way into the river through fivewastewater outfalls and two surface drains (Fig. 1). Theriver is also facing extreme flow variations (i.e., 10–10,000 m3/s). DO is one of the most important parametersfor the survival of aquatic life. During low-flow periods,most of the river reach (60 km) near the city of Lahorebecomes anaerobic. Nitrogenous biochemical oxygen de-mand (NBOD) and carbonaceous biochemical oxygen de-mand (CBOD) are the primary sources of oxygen depletionin the Ravi River [8]. Therefore, along with CBOD, removalof NBOD also needs to be considered to meet DO standardsin the Ravi River while evaluating different WQM alterna-tives. In this connection, un-ionized ammonia is anotherimportant water quality parameter to be managed toensure a healthy environment for fish. High concentra-tions of un-ionized NH3 are toxic to fish. Most regula-tory agencies have set a standard of 0.02 mg/L for un-

ionized ammonia [9]. Chapra reported a range of 0.01to 0.1 mg NH3-N/L for fish mortality [12]. Haider alsofound that the concentration of un-ionized ammonia inthe Ravi River is greater than the required standards forfish [10]. Different water quality control alternatives,such as conventional wastewater treatment, flow aug-mentation, wetlands, waste stabilization ponds (WSP),and wastewater transportation with primary treatment,have specific effects on nitrogen removal and riverbiokinetics. Furthermore, these variations in nitrogenremoval may have different resulting impacts on un-ionized ammonia in the river. There is a possibility thatthe river meeting the DO standards with CBOD-basedload allocations is not complying with un-ionized am-monia standards due to incomplete nitrification. Thus,there is a need for the development and implementationof an optimum WQM program, keeping in view boththe DO and un-ionized ammonia standards for the RaviRiver.

The main objective of this research work is to eval-uate different WQM alternatives by using a calibratedand verified water quality model for compliance of boththe DO and un-ionized ammonia standards for fish inthe Ravi River.

2 Water Quality Management Framework

With the increase in population and industrial develop-ment in the city of Lahore, the present and future

Scale (KM)

0 10 20

N

SHAHADRA GAUGING STATION

SIPHON (0.0KM)

NE DISTRICT OUTFALL (26.1 KM)

MAIN OUTFALL (34.1 KM)

GULSHAN RAVI OUTFALL (35.5KM)

MULTAN ROAD OUTFALL (45.3KM)

SHAHADRA OUTFALL(27.9 KM)

HUDIARA DRAIN (60.3 KM)DEG DRAIN(63.0 KM)

QB LINK CANAL(85.0 KM)

BALLOKI HEADWORKS (98.7 KM)

Fig. 1 Location of Ravi Riverand study reach showingdifferent locations ofwastewater outfalls and surfacedrains

452 H. Haider, W. Ali

pollution loads pose a continuous threat to the RaviRiver water quality. To improve this situation, a com-prehensive WQM framework for the evaluation of dif-ferent alternatives with estimated future loads (i.e.,inputs) using a calibrated and verified DO model isshown in Fig. 2. WQM programs are planned to meetfuture needs based on the design periods of differentwaste control alternatives. In this regard, WQM in thisstudy is planned for the year 2025. Haider estimatedfuture pollution loads of both the ultimate CBOD(CBODU) and ultimate NBOD (NBODU) [10]. Haiderand Ali developed, calibrated, and verified DO andnitrification models for the Ravi River [1, 8]. Requiredadjustments in biokinetic rate coefficients of the RaviRiver with varying levels of wastewater treatment werestudied by Haider and Ali [2]. The same has been usedin this study to simulate DO and un-ionized ammoniaprofiles at different levels and degrees of treatment fordifferent water quality control alternatives under critical

low-flow conditions to meet the required water qualitystandards in the Ravi River.

2.1 Assessment of Future Loads

Future CBODU and NBODU loads estimated for all thewastewater sources from the city of Lahore to the RaviRiver for the year 2025 are presented in Table 1.

2.2 Low-Flow Analysis for Ravi River

Conventionally, the MA7CD flow once in 10 years, alsoknown as 7Q10, has been used as the critical flow for DOmanagement in the rivers. The flow data from 1967 to 2004was analyzed to determine MA7CD in the Ravi River [11].MA7CD is found to be 9.2 m3/s (325 cfs) by carrying outthe cumulative probability analyses of the data [12, 13].

Water Quality Modeling

Assessment of Future Loads a

Calibrated and Verified Water Quality Model c

Reaction Kinetics b

- Effect of wastewater treatment on biokinetic rate coefficients

- Appropriate rate coefficients

Low Flow Analysis (MA7CD)

Water Quality Management

Design of water quality improvement alternatives

Conventional wastewater treatment

Flow augmentation

Wastewater transportation

Low cost treatment

Construction of wetlands

Simulation ResultsCost Estimates

Wastewater treatment cost

Wastewater transportation cost

Cost of waste stabilization

ponds Evaluation of Alternatives

Fig. 2 Framework of WQMfor Ravi River. a Haider [10], bHaider and Ali [2], c Haider andAli [1, 8]

Evaluation of Water Quality Management Alternatives 453

2.3 Coupled Hydrodynamic and Water Quality Model

A hydrodynamic model coupled with the DO model tocater to extreme flow variation in the Ravi River wasdeveloped by Haider and Ali [8]. Later, the DO modelincluding nitrification was calibrated and verified withtwo different data sets. Calibration was done undermedium-flow conditions (431.5 m3/s), whereas verifica-tion was done under low-flow conditions (52.6 m3/s).Both the data sets showed close agreement with themodel results [10]. The hydrodynamic model consistsof power functions (Eq. 11a–c given in Table 2) torelate mean velocity, depth, and width of the cross-section to the discharge in the Ravi River. To estimatehydrodynamic parameters (velocity and depth) of theRavi River, the same equations have also been used inthis research. Details can be seen in Haider and Ali [8].

Table 2 presents the mathematical equations used tosimulate different hydrodynamics and water quality process-es in the Ravi River. Initial concentrations of the pollutantsat the points of wastewater discharges (following completemixing assumption) are calculated by using Eq. 1. TheCBOD oxidation process is modeled as the first-order reac-tion using Eq. 2 [13]. Nitrogen in the wastewater is presentin two forms, organic nitrogen (Org-N) and ammonia nitro-gen (NH4-N) and is collectively known as total Kjedahlnitrogen (TKN). Nitrification is a process of conversionof NH4-N into nitrates (NO3) and is an oxygen-demanding process. Oxygen consumed in this reaction bynitrifiers is considered as NBOD and can be simulated byusing Eq. 3 at any point in the river, whereas the NBODUcan be estimated by using Eq. 4. Nitrification in the riveressentially occurs as a series of sequential reactions includingconversion of Org-N into NH4-N, NH4-N into nitrites, and

then nitrites into nitrates and thus can be modeled in Eqs. 5and 6. Fraction of un-ionized ammonia from the total ammo-nia is calculated by using Eq. 7 as a function of pH andtemperature.

To model atmospheric reaeration in the Ravi River, theO’Connor–Dobbins formula was found to be the least sen-sitive to cater to highly variable flow in the Ravi River [14,15]. Therefore, Eq. 8 is used to model DO in the Ravi Riverfor the purpose. Now with all the wastewater inputs andreaction parameters, the one-dimensional, multireach, first-order steady-state model (Eq. 9) considering both the CBODand NBOD is used to simulate DO in the Ravi River [13].Based on the river temperature during winter low-flow con-ditions, Eq. 10a–c are used to apply temperature correctionto CBOD, NBOD, and reaeration rate coefficients estimatedat 20 °C [10].

The turbidity varies between 100 and 220 nephelo-metric turbidity units (NTU) in the Ravi River. Theseturbidity levels are significantly high for the productionof photosynthesis [10]. Moreover, the high variations inthe river flow tend to resuspend the settled organicsolids. Therefore, the DO model does not include boththe benthic oxygen demand and the oxygen sources andsinks due to photosynthesis.

2.4 Biokinetic Rate Coefficients of Treated Effluents

According to Haider and Ali, the river biokinetic ratecoefficient for CBOD and NBOD (i.e., Kc and Kn) werefound to be 0.36 and 0.34 day−1, respectively, fromcalibration and verification studies when the river wasreceiving raw wastewater [1]. Haider and Ali estimatedthe effect of treatment of the Lahore wastewaters on thecarbonaceous and nitrogenous biokinetic rate coefficients

Table 1 Estimated CBODU and NBODU loads to the Ravi River for year 2025

Sr. no. Wastewater outfalls/surface drains CBODU NBODU BODU

Concentration(mg/L)

Flow (m3/s) Load(tons/day)

Concentration(mg/L)

Flow (m3/s) Load(tons/day)

Load(tons/day)

(A) Wastewater outfalls

1. NE District 287 11.3 280 174 11.3 170 450

2. Shahadra 657 2.3 131 199 2.3 40 170

3. Main Outfall 277 6.7 160 208 6.7 121 281

4. Gulshan Ravi 297 5.5 141 158 5.5 75 216

5. Multan Road 318 3.5 96 201 3.5 61 157

(B) Surface drains

6. Hudiara Drain 322 17.5 487 149 17.5 225 711

7. Deg Drain 379 9.3 305 129 9.3 104 408

Total 56.1 1,600 56.1 794 2,394


(Kc and Kn) of the Ravi River [2]. Their study resultssuggested that the Ravi River rate coefficients requirereduction by a factor ranging between 1.5 and 5, depend-ing on the level of treatment (i.e., primary, secondary,

and secondary with nitrification). In this study, the RaviRiver biokinetic rate coefficients are adjusted with differ-ent levels of wastewater treatment to simulate DO in theriver under different water quality alternatives (Table 3).

Table 2 Equations used in the modeling and management of Ravi River water quality

Process Equation/model Parameters Eq.

TDS mass balanceS0 ¼ QuSuþQeSe

QuþQe

S0 is the TDS concentration in the river, mg/L 1Qu is the river flow u/s of the outfall, m3/s

Su is the TDS concentration in the river waterupstream of the outfall, mg/L

Qe is the outfall flow, m3/s

Se is the TDS concentration in the wastewater, mg/L

CBODLcr ¼ Lcoe�Kcr

xU

Lcr is the CBOD, mg/L 2Lco is the initial CBOD in river at outfall, mg/L

Kcr is the river CBOD removal rate, day−1

NBODLn ¼ Lnoe�Kn

xU

Ln is the NBOD in the river downstream, mg/L 3Lno is the initial NBOD in river at outfall, mg/L

Kn is the river NBOD deoxygenation rate, day−1

Nitrification (NBODU)Ln ¼ 4:57 TKNÞð Ln is the NBODU, mg/L 4

TKN is the total Kjedal nitrogen, mg/L

Nitrification(Org-N→NH3-N)

No ¼ Nooe�KoaxU

No is the Org-N, mg/L 5Noo is the initial concentration of Org-N, mg/L

Koa is the nitrification rate coefficient forconversion of Org-N into ammonium

x is the distance in the river, m

U is the velocity in the river, m/day

Nitrification(NH3-N→NO3-N)

Na ¼ Naoe�KanxUþ

KoaNooKan�Koa

e�KoaxU � e�Kan

xU

� �Na is the NH4-N, mg/L 6Nao is the initial concentration of NH4-N, mg/L

Kan is the nitrification rate coefficient forconversion of NH4-N into NO3-N, day

−1

Un-ionized ammonia fractionNH3½ � Hþ½ �NH4

þ½ � ¼ KK is the equilibrium coefficient 7

pK ¼ 0:09018þ 2;729:92T

Fu is the fraction of un-ionized NH3 (in total NH3)

Fu ¼ NH3½ �NH3½ �þ NH4

þ½ �T is the river temperature

ReaerationO’Connor–Dobbins Ka ¼ 3:93 U0:5

H1:5

H is the average depth, m 8U is the river velocity, m/s

DO (modifiedStreeter–Phelps) D ¼ D0eKat þ KcLo

Ka�Kcr

e�Kcr t � e�Ka tð Þ þ KnLnoKa�Kn

e�Kn t � e�Katð Þ

Kc is the CBOD deoxygenation rate, day−1 9Kcr is the CBOD deoxygenation rate, day−1

Temperature correctionsKað ÞT ¼ Kað Þ20 1:024ð ÞT�20

Kcrð ÞT ¼ Kcrð Þ20 1:047ð ÞT�20

Knð ÞT ¼ Knð Þ20 1:08ð ÞT�20

(Ka)T is the Ka at river temperature, day−1 10a(Ka)20 is the Ka at 20 °C, day−1

(Kcr)T is the Kr at river temperature, day−1 10b(Kcr)20 is the Kr at 20 °C, day−1

(Kn)T is the Kn at river temperature, day−1 10c(Kn)20 is the Kn at 20 °C, day−1

Hydrodynamic model U=aQb B is the river top width, m 11a

H=cQd Q is the river flow, m3/s 11b

B=eQf a, b, c, d, e, and f are the empirical constants 11c

Source: Thomann and Mueller [12], Chapra [13]


3 Formulation of Alternatives

Following alternatives are formulated to come up with themost cost-effective solution for WQM of the Ravi River:

A-1 Conventional wastewater treatmentA-2 Flow augmentationA-3 Wastewater transportationA-4 Low-cost treatmentA-5 Constructed wetlands

The background conditions of the Ravi River for theevaluation of the above alternatives are given in Table 4.

3.1 A-1: Conventional Wastewater Treatment

MA7CD in the Ravi River is 9.2 m3/s, whereas the estimat-ed wastewater flows from all the outfalls and surface drainsfor year 2025 would be about 56 m3/s. It means that thefuture wastewater flows will be about six times higher thanthe minimum critical river flow. Under such conditions,activated sludge process (ASP), trickling filters (TF), andaerated lagoons (AL) are the possible wastewater treatment

options to achieve high treatment efficiencies (i.e., 90 % orgreater).

Formation of slime layer under normal conditions in TFdue to inadequate oxygen generates odor problem.Sometimes, formation of small pools and puddles of wateron the water surface in TF due to inadequate recirculation,aging of media, inappropriate gradation of media, and pres-ence of debris decrease the BOD removal efficiency [16].As far as the nitrification efficiency of TF is concerned,BOD loading rate of as low as 0.08 kg BOD/m3/day isrequired to achieve 90 % efficiency. TF efficiency signifi-cantly reduces to 50 % at a loading of about 0.22 kg BOD/m3/day. Moreover, the area, thickness, and density of bio-film and its wetting efficiency are always difficult to predictprecisely due to variations in BOD to TKN ratios. As thisratio increases, heterotrophic microorganisms cover thegreater portion of the TF packing area and, therefore, thenitrification rate decreases [17]. The data collected at MainOutfall shows quite large diurnal variations in BOD/TKNratio (i.e., 3.3–6.9) [18], which can significantly affect thenitrification rate. Therefore, due to the flexibility in modifi-cations for nitrogen removal up to 98 % and less landrequirements to produce high-quality effluent, ASP is se-lected as the conventional wastewater treatment option.

The NBODU concentration, which is almost equal tothe CBODU in Lahore wastewater (Table 1), is also animportant consideration for selecting a treatment pro-cess. AL are good in nitrogen removal, but to achieveyear-round nitrification (>90 %), keeping the requiredalkalinity and DO concentrations, about 6–7 days ofhydraulic retention time (HRT) is required [17]. Forsuch higher HRT, the land requirements are high [19].Therefore, they are not considered as a potential alter-native to treat large volumes of wastewater from thecity of Lahore [2].

Table 4 Ravi River upstream offirst outfall and QB Link Canalconditions for WQM

Ravi River

MA7CD at Shahadra gauging station=9.2 m3/s

River average temperature during winter low flow season=17 °C

pH07–7.5

DOSATURATION=9.67 mg/L

Actual DORIVER=8.0 mg/L (85 % saturation as per field observations)

BOD5=7.0 mg/L

CBODU=7.9 mg/L

NBODU=5.5 mg/L

QB Link Canal

Average annual flow=395.6 m3/s (1995–2004 data)

BOD5=6.0 mg/L

CBODU=6.7 mg/L

NBODU=4.57 mg/L

Table 3 Biokinetic rates for Ravi River with different levels oftreatment

Type of effluent Kc (day−1) Kn (day

−1)

Raw wastewatera 0.36 0.34

Primary treated 0.24 0.22

Secondary treated 0.12 0.10

Secondary+nitrification 0.07 0.05

Source: Haider and Ali [2]a River rate coefficients (presently river is receiving raw wastewaterwithout any treatment)


3.2 A-2: Flow Augmentation

The average monthly flow in the MR Link Canal rangesbetween 36 and 565 m3/s during the months of April toOctober (1995–2004) [11]. This means that MR Link Canalcan carry up to 565 m3/s. The possibility of flow augmen-tation from MR Link Canal from Siphon through the RaviRiver under low-flow conditions (i.e., MA7CD) to augmentriver flow to achieve the desired DO levels is also investi-gated in this research.

3.3 A-3: Wastewater Transportation

Transportation of NE District, Main Outfall, Gulshan Ravi,Multan Road Outfalls, and Hudiara Drain flows through acollector channel to the QB Link Canal confluence point isanother potential alternative for Ravi River WQM. In thisway, benefit of dilution from QB Link Canal can be utilizedto minimize the cost of wastewater treatment. Average an-nual flow in QB Link Canal is 395.6 m3/s, which is aboutnine times higher than the estimated future wastewater flowfrom the previously mentioned sources of wastewater. DegDrain joins the UCC canal at about 20 km upstream andcommonly utilizes the dilution from UCC. During the canalclosure period, only Deg Drain’s flow enters into the RaviRiver; therefore, wastewater treatment before the confluenceof UCC is the only viable option for the Deg Drain waste-water in this alternative.

3.4 A-4: Low-Cost Treatment

WSP have been extensively used for domestic and industrialwastewater treatment all over the globe for almost a century.There are different types of ponds used to meet variouswater quality objectives (e.g., anaerobic, facultative, andmaturation ponds). The design details are given by variousresearchers [20–22]. BOD removal up to 85 % from facul-tative ponds is frequently reported [23]. WSP system con-sisting of anaerobic and facultative ponds as a rule of thumbproduces an effluent generally suitable for restricted irriga-tion. In case of unrestricted irrigation use, maturation pondsare required to improve the microbiological quality of thewastewater [24].

WSP are also considered as a potential alternative for theRavi River WQM. These are the most commonly used aslow-cost technology particularly in hot climates. Their lowconstruction and operational costs make them more suitablefor developing countries [20]. The Water and SanitationAgency, Lahore Development Authority (WASA-LDA) fi-nalized the plan for WSP construction for the Lahore waste-waters based on the recommendations of the Balfours studyin 1987, but funding could not be arranged till now.Moreover, the proposed WSP construction site lies in the

flood plan, which creates land acquisition, technical, andsocioeconomic issues related to local occupants andirrigation department as well due to large area require-ments [25, 26].

3.5 A-5: Constructed Wetlands

Constructed wetlands are natural wastewater treatment sys-tems and improve water quality through their vegetation,soil, and microbial environment. These systems are morecost-effective than the conventional wastewater treatmentsystems and have lower operation and maintenance(O&M) costs as well. Moreover, they are esthetically pleas-ing and produce less or no odor-related issues in comparisonto the other treatment processes [27]. Their application totreat municipal and industrial wastewaters has been in-creased immensely since 1980 [28].

There are two basic types of constructed wetlands: (1)subsurface flow (SF) wetlands and (2) free water surface(FWS) wetlands. Both types apparently look similar to amarsh and can be constructed using native vegetation andsoils. Wetlands can serve the purpose of wastewater treat-ment and can provide a habitat for a number of species andwildlife as well. They can provide a comparable efficiencyas any other treatment option (e.g., ASP and WSP) if influ-ent is pretreated at the primary level. SF-type wetland sys-tems are designed to keep the water level below the rock orgravel media, whereas the FWS type of systems commonlyconsist of a basin or channels along with a natural or con-structed barrier of clay or other impervious geotechnicalmaterials to avoid the possibility of seepage. The soil isused to keep the roots of vegetation intact, and the shallowwater flows through the system. The details have beenprovided by PWTB, USEPA, and Rowe and Abdel-Magid[28–30].

The wastewater from NE District, Main Outfall, GulshanRavi, and Multan Road Outfalls can be transported up to theHudiara Drain, and after combining the flow with HudiaraDrain, the wastewater (i.e., 44.5 m3/s in year 2025; Table 1)can be treated through FWS after primary treatment beforedischarging into the Ravi River. Downstream of HudiaraDrain, there is a potential site with wide and shallowcross-section and low velocities for the FWS type of wet-lands. This site is near the flood plain, but due to the verywide river cross-section and shallow water depth, evenduring the flood season, the cost of the flood protectionworks would be low. The proposed site also has a mildslope due to the natural topography of the area, so the watercan flow through gravity. Native soil is a well-graded mixtureof sand, silt, and clay, which can provide protection againstseepage. Moreover, there is no rural locality within or nearthe proposed location, thus the possibility of problems as-sociated with insects can also be neglected. The FWS type of


wetland after applying primary treatment is also consideredas a potential alternative for WQM of the Ravi River.

For the design of the FWS system, the following generalequation of water balance is used for a constant depth [29]:

Qi � Qo þ P � ET ¼ 0 ð11Þwhere Qi is the influent wastewater flow, Qo is the effluentwastewater flow, P is the precipitation, and ET is the evapo-transpiration. The maximum allowable hydraulic loadingrate should range between 2.5 and 5 cm/day for FWS.HRT (td) depends on the tolerance of the plant and the depthof water in the wetland. BOD removal rates range between49 and 95 %. The wetland area can be calculated using thefollowing equation [29]:

Ar ¼ Q lnCo � lnCe � 0:6539ð Þ65� d � KT

ð12Þ

where Ar is the wetland area, d is the water depth, Ce is theeffluent BOD5, Co is the influent BOD5, and KT is the first-order reaction rate constant. The area of the constructedwetlands for Hudiara Drain including outfalls and DegDrain is estimated using Eq. 12 with the design informationgiven in Table 5.

4 Cost Estimates of Different Alternatives

The cost of the wastewater treatment depends on the type oftreatment and required degree of treatment (DOT) to meetspecific water quality objectives of the receiving water body.

The reported ranges of the removal efficiencies with level oftreatment from various sources are given in Table 6.

To estimate the present tentative construction and opera-tional cost of the ASP wastewater treatment plant for WQMof the Ravi River, cost estimates of an ASP for the year 2006recommended for the southwest disposal station (alsoknown as Mehmood Booti disposal station) are obtainedfrom WASA-LDA [32]. The design flow of the ASP was250,000 m3/day, and designed at 90 % DOT. Descriptionincluding important design parameters and cost of this treat-ment plant is given in Table 7. The total construction cost ofthe wastewater treatment facility, including bar screen, gritchamber, primary sedimentation tank, aeration tank, second-ary sedimentation tank, tertiary treatment plant, sludgethickener, sludge drying beds, piping system, staff residen-ces, generator room, flood protection bund, landscaping,etc., was 8,935 million Rs, whereas the annual O&M costwas 719 million Rs in year 2006 [32]. As these costs werefor the year 2006, the present costs for the year 2010have been calculated by using 10 % escalation per year.Annual energy requirements are 60.5 million kWh. Thecapital and annual O&M costs after applying escalationare 13,082 million Rs and 1,053 million Rs, respectively, forthe year 2010. The present value of the O&M cost for thefuture years (2010–2025) are calculated by using the presentworth method with a discount rate of 10 %.

Burn used cost functions by associating the capital andO&M costs of the wastewater treatment with the BODremoval efficiencies at 35, 80, 93, and 97 % [33]. The ratiosgiven by Burn between the costs at these percent removalsare used to determine wastewater treatment costs at varyingdegrees of treatment for the southwest wastewater treatmentplant described in Table 7 (Fig. 3). The values of CBODUand NBODU removals given in Fig. 3 correspond to280 mg/L of CBODU and 40 mg/L of TKN (NBODU=

Table 5 Design criteria used for design of wetlands

Pretreatment=primary

Wastewater flow up to Hudiara including outfalls(left side)=44.5 m3/s

Raw water BOD5 up to Hudiara=246 mg/L

Influent BOD5 up to Hudiara Drain=148 mg/L(assuming 40 % reduction from primary treatment)

Effluent BOD5=50 mg/L

Percent removal of CBOD with primary treatment=80 %

Percent removal of TKN=50 %

Mean summer temperature=31 °C

Mean winter temperature=14 °C

Mean annual rainfall=51.4 mm

Wetland slope=0.1 %

K20=0.0057 day−1

KT(Summer)=0.01626 day−1

KT(Winter)=0.00322 day−1

Wetland depth=0.3 m

Porosity=0.75

Source: Rowe and Abdel-Magid [29], USEPA [30]

Table 6 Efficiencies of the waste reduction with varying levels oftreatment

Level of treatment Percent removal

CBOD TKN

Primary treateda 25–40 10–20

Secondary treated (ASP)a 80–90 70–80

Secondary+nitrification (ASP)a 90–98 90–98

WSPb 80–85 50–80

Primary+constructed wetlandsc,d 60–85 40–50

a Thomann and Mueller [13]b IRC [31]c PWTB [28]d USEPA [30]


183 mg/L). The relationship between CBOD and NBODremovals is based on the ranges given in Table 6.

The land requirement for the wastewater treatment plantmentioned in Table 7 is 7.59 ha for 250,000 m3/day ofwastewater flow [32]. Therefore, for 4,847,000 m3/day ofthe wastewater generated from the city of Lahore up toyear 2025, about 147.3 ha of land is required. The costfunction developed using the data given in Table 8 to cal-culate the wastewater treatment costs per kilogram of totalBOD removed at different levels of treatment is shown in

Fig. 3. The wastewater treatment cost in rupees per kilogramof BOD removed at different levels of treatment is given inTable 8.

Collector channel is used in A-3 and A-5 for wastewatertransportation up to the QB Link Canal confluence point.The Japan International Cooperation Agency (JICA) carriedout a study for Lahore water supply, sewerage, and drainingimprovement [34]. They proposed the construction of awastewater treatment facility at Multan Road Outfall, andthe transportation of Main Outfall and Gulshan Ravi waste-water flows with the help of a collector channel up to theMultan Road pumping station (PS) for a combined waste-water treatment facility. The capital cost of this 7.1-km-longcollector channel for a design flow of 14.2 m3/s was 905.5million Rs [34]. This proposed collector channel was cov-ered with reinforced cement concrete slabs. Therefore, thecost of the collector channel per kilometer was8,981,200 Rs/m3/s of flow. The cost analyses of the collec-tor channel to transport wastewater from NE District outfallto QB Link Canal are given in Table 9. The total cost of thecovered collector channel is 16,630 million Rs.

The land requirements of the collector channel are deter-mined by considering a 30-m-wide right-of-way with a 10-m-wide channel, maintenance road, and some reserve areafrom North District Outfalls to Hudiara Drain, whereas awider 35-m strip to cater to the flow of Hudiara Drain isconsidered with a 15-m-wide channel from Hudiara Drain toQB Link Canal (Fig. 1) [34]. The land requirement of thecollector channel is estimated to be 228.7 ha. Additionalland requirements for the ASP type of wastewater facilitiesat Shahadra Outfall and Deg Drain are 30.4 ha [32]. Thus,the total land requirement of this alternative is 259 ha.

As per JICA study for Lahore water supply, sewerage,and draining improvement, the unit cost of WSP as a waste-water treatment alternative was also estimated [34].According to their estimates, the cost of the anaerobic andfacultative ponds in series was 7,351 million Rs for790,000 m3/day of wastewater. The annual O&M cost forsludge disposal for the same flow was 38.7 million Rs. Ifmaturation ponds are also added after facultative ponds inseries, the capital and annual O&M costs becomes 9,556million Rs and 46.4 million Rs, respectively. Therefore, forabout 4,847,000 m3/day of wastewater, the estimated capitaland O&M costs with a discount rate of 10 % for the 15-yeardesign period of the WSP are 58,630 million Rs and 2,165million Rs, respectively, for this alternative.

The land requirements are calculated based on the JICAstudy [34]. For about 1,000,000 m3/day of wastewater flow,around 506 ha of land is required for anaerobic and facul-tative ponds in series. About 605 ha land would be requiredfor maturations ponds with 5 days detention time to treat1,000,000 m3/day of wastewater. Thus, the total land re-quired for 1,000,000 m3/day of wastewater is 1,111.3 ha.

Table 7 Description of southwest WWT plant

Plant description

Type=ASP

Design flow=250,000 m3/day

Influent BOD=200 mg/L

Influent BOD load=50,000 kg/day

Effluent BOD=20 mg/L

Effluent BOD load=5,000 kg/day

Removal efficiency=90 %

Land requirement=7.6 ha

Cost

Capital cost in year 2006=8,935 million Rs

Annual escalation=10 %

Present capital cost=13,082 million Rs (2010)

Annual O&M cost including sludge disposalcost=114 million Rs (excluding energy cost)

Annual energy requirements=60.5 million kWh

Annual energy cost=605 million Rs

Total annual O&M cost in year 2006=719 million Rs

Annual O&M cost for year 2010=1,053 million Rs

Discount rate=10 %

O&M cost for 15 years (2025)=8,009 million Rs(based on present worth method)

Total capital+O&M cost=21,091 million Rs

Source: WASA-LDA [32]

Fig. 3 Total cost function with kilograms of BOD per day removed


Therefore, for the WSP facility (A-4) at all the outfalls andsurface drains, the total land requirement is 5,386.4 ha.

The estimated areas of the FWS type of constructedwetlands is 21,617 ha using Eqs. 11 and 12. The landrequirement of the primary wastewater facility is 46.5 hafor the collected wastewater from the left bank of the riverincluding Hudiara Drain. Additional areas of about 228.7 hafor the collector channel and 1,113.7 ha for WSP atShahadra Outfall and Deg Drain would also be required.Therefore, the total land requirement for A-5 is 4,014.5 ha.The cost estimates of wetlands for local conditions inPakistan are not available; thus, this planning alternative isnot included in cost evaluation. However, water qualitysimulations are carried out to see the impact on DO levelsin the Ravi River.

The land cost of 2,000,000 Rs/ha is reported for WASA-LDA development works as per Land Acquisition ActPunjab [34]. In this study, the same unit cost is used forthe evaluation of the previously mentioned alternatives.

5 Evaluation of Water Quality Management Alternatives

5.1 A-1: Conventional Wastewater Treatment

The most commonly used DO standard in the rivers for thesurvival of fish life is 4 mg/L [12, 13]. However, keeping inview the present critical low-flow conditions of the RiverRavi, simulations are also carried out using the DO model atdifferent degrees of wastewater treatment to achieve 1, 2, 3,

4, and 5 mg/L of DO levels for the purpose of comparison.The background river and QB Link conditions are as givenin Table 4. The simulation results for 1, 4, and 5 mg/L of DOstandards are shown in Fig. 4. It can be seen in the figurethat, even to achieve 1 mg/L of DO levels in the River Raviat MA7CD flow, 67 % BODU removal efficiency are re-quired. Higher efficiencies of 87 and 95 % would be re-quired for 4 and 5 mg/L DO levels, respectively. The graphbetween the minimum DO levels attained at varying degreesof treatment for MA7CD river flow is shown in Fig. 5.

Ammonia toxicity is also a water quality problem in theRavi River. Un-ionized ammonia standards of 0.02 mg/L forthe survival of fish are recommended by the USEPA, whichare being violated even under high-flow conditions in theRavi River due to the discharge of untreated domestic andindustrial wastewaters [10].

The chemical equilibrium with NH4 ions and NH3 iswritten as [9]:

NH4þ $ NH3 þ Hþ ð13Þ

The equilibrium constant for the above equation is 5.56×10−10M/L [35]. NH4

+ ions predominate between pH 6.0 and9.0 in natural water bodies. The reaction is also a function oftemperature. Higher temperatures keep the reaction towardsthe left-hand side (i.e., most of the ammonia in un-ionizedform).

Total ammonia levels in the Ravi River are calculated forfuture conditions (year 2025) and un-ionized ammonia con-centrations are then determined by applying the fractionbetween total ammonia and un-ionized ammonia using Eq.

Table 8 Wastewater treatmentcost for different levels oftreatment

aO&M cost for 15 years(2010–2025)

Sr. no. DOT (%) Wastewater treatment Cost (Rs/kg of BOD removed)

Capital O&Ma Total

1 40 78,100 43,100 121,200

2 60 89,400 52,100 141,500

3 80 113,600 68,200 181,800

4 90 130,600 80,300 210,900

5 >90 160,400 91,800 252,200

Table 9 Cost analysis of collector channel

Reach no. Reach Length (km) Flow (m3/s) Unit costa (Rs/m3/s) Total cost (million Rs)

1 NE District–Gulshan Ravi 8.5 11.3 8,981,200 862.64

2 Gulshan Ravi–Multan Road 10.7 23.5 8,981,200 2,258.3

3 Multan Road–Hudiara Drain 15.0 27.0 8,981,200 3,637.4

4 Hudiara Drain–QB Link Canal 24.7 44.5 8,981,200 9,871.7

Total 16,630.0

a Unit cost for 1 km of collector channel


7. The same river conditions as given in Table 4 are con-sidered for the simulations. The results are shown in Fig. 6.The effect of wastewater treatment on the total nitrogenremoval is given in Table 6. Simulations are carried outafter applying 80 and 90 % NH4-N removal (Fig. 7a, b).These efficiencies for NH4-N removal can be achieved,corresponding to 90 and 95 % CBOD removals.

Rott suggested that the wastewater treatment plants op-erated for NH4-N (ammonia–nitrogen) standards of 1–3 mg/Land minimum effluent DO standards (say 2 mg/L) have a

much superior effluent than conventional secondary treatedeffluent in terms of CBOD5 standards [36]. Therefore, forsuch effluents, time-consuming CBOD5-based waste loadallocations can be altered on the basis of un-ionized ammo-nia standards. On the other hand, NH4-N standards cannotbe based on CBOD5 standards due to the fact that, evenwith 10–15 mg/L of CBOD5, effluent may not necessarilybe meeting ammonia standards. This could be more signifi-cant in the wastewater treatment systems having low de-tention times. However, streams with low pH can assimilate

QRIVER = 9.2 m3/s

SIPHON

98.7KM

North District Outfall PS (26.14KM)

SHAHADRA GS

26.8KM

Shahadra PS(27.9 KM)

Main Outfall (34.1KM)

Gulshan Ravi PS (35.5KM)

Multan Road PS (45.3KM)

RAVI RIVER

Deg Drain(63KM)

Hudiara Drain(60.3KM)

QB Link Canal(85KM)

BALLOKI HW

0.0KM

Deg DrainUCC Canal

ASP WASTEWATER TREATMENT PLANT

Degree of treatment = 95%

0

2

4

6

8

10

0 20 40 60 80 100Distance (Km)

DO

(mg

/L)

Minimum DO level = 5mg/L


0

2

4

6

8

10

0 20 40 60 80 100Distance (Km)

DO

(mg

/L)



0

2

4

6

8

10

0 20 40 60 80 100Distance (Km)

DO

(mg

/L)


Fig. 4 DO simulations with ASP wastewater treatment facility operated at varying DOT for MA7CD


slightly higher ammonia values without violating un-ionizedammonia standards. For such cases, the CBOD5 standardsshould not be established based on un-ionized ammoniastandards, and more detailed waste load allocation studieswould be required [36]. In the case of Ravi River, the un-ionized ammonia standard of 0.02 mg/L requires higherDOT (i.e., 95 % CBODU removal) than for DO standardsof 4 mg/L (i.e., 90 % CBODU removal). However, thisvalue can be relaxed by studying the threshold toxicityconcentration for the site-specific fish species surviving inthe Ravi River under low-flow conditions.

5.2 A-2: Flow Augmentation

It can be seen in Fig. 5 that a very high level of treatment(90 %) is required to obtain the required DO standards of4 mg/L under low-flow conditions (MA7CD). If the riverflow is augmented, the DOT can be reduced. Simulationsare carried out to determine the required flow augmentationto achieve 4 mg/L of DO in the river (Fig. 8).

The simulation results in Fig. 8 show that, without anytreatment, a flow of 416 m3/s of freshwater is required to bediverted fromMRLink Canal to augment the river flow duringwinter low-flow conditions. In the case of primary treatmentwith 40 % of CBODU and 20 % of NBODU removal, about210 m3/s of flow augmentation to the MA7CD flow is re-quired. Furthermore, if diversion of about 19 m3/s of thefreshwater can be made possible through Siphon to the Ravi

River, the required DO standards of 4 mg/L can be achievedwith 80 % of CBOD and 70 % of NBOD removal. However,the required amount of freshwater from MR Link Canal toaugment the River Ravi flow needs to be looked into, keepingin view the availability of water during the low-flow periodwithout affecting the downstream agricultural requirements.

5.3 A-3: Wastewater Transportation

The simulation results of this alternative with the transporta-tion of wastewater are shown in Fig. 9a, b. The average annualflow of 396 m3/s (Table 4) from QB Link Canal can provideabout 1:10 dilution, even at MA7CD (9.2 m3/s) in the RiverRavi. But the river deoxygenation rate coefficient (Kcr) for rawwastewater (Table 3) is too high to maintain the DO above4 mg/L and, therefore, the DO approaches from lesser than4 mg/L at 92 km (i.e., about 7.0 km upstream of Balloki HW)to 2mg/L at Balloki HW (98.7 km). The reaeration rate (Ka) of0.70 day−1 is also low in the last reach (QB Link to BallokiHW) due to more confined slower and deeper river section [8]near the Balloki HW (Fig. 9a). This part of the Ravi River is apotential spawning ground for fish and lower DO levels cansignificantly affect the fish life. One of the options to mitigatethis impact is the provision of the primary treatment facility atthe end of the collector channel before discharging into theRavi River. In this way, 4 mg/L of DO standards can bemaintained up to Balloki HW (Fig. 9b).

Shahadra Outfall being the only discharge point on theright bank of the river, transportation of wastewater fromShahadra is neither a technically feasible nor a financiallyviable option. Deg Drain will remain at the location alreadyspecified before joining UCC Canal (Figs. 4 and 8). At bothlocations, 85 % DOT is required. In case of no treatmentfacility at Shahadra Outfall, the DO level straight awayapproach zero at the confluence point in Ravi River(27.9 km) due to discharge of 175,430 kg/day of totalBOD load. However, QB Link Canal needs to be operatedat an average annual flow of 396 m3/s (Table 4) to providethe required dilution with or without primary treatment ofthe transported wastewater.

Fig. 5 Graph showing required DOT to attain a certain DO level inRavi River at MA7CD river flow

QRiver = 9.2 m3/spH = 7.4TRiver = 17oC

Kan = 0.34 day-1

0.00

0.10

0.20

0.30

20 40 60 80 100Distance (Km)

Un

-ion

ized

NH

3-N

(mg

N/L

)

Un-ionized Ammonia

Un-ionized Ammonia Stand.

Un-ionized NH3-N standard = 0.02mg/L

Fig. 6 Un-ionized ammonia levels in Ravi River at MA7CD in the future year 2025 receiving raw wastewater


5.4 A-4: Low-Cost Treatment Option

Anaerobic, facultative, and maturation ponds in series canprovide 85 % of CBOD and 75 % of NBOD removal(Table 6) [31]. Moreover, maturation ponds effluent is suit-able for irrigation as well. As an alternative of DO manage-ment of Ravi River, simulations are carried out with theWSP type of wastewater treatment facilities at all the out-falls and surface drains. The results are shown in Fig. 10a, b.The results revealed that 3 mg/L of DO at the critical pointscan be achieved with WSP (Fig. 10a). It means that, underlow-flow winter conditions, the wastewater treatmentoptions with higher removal efficiencies (i.e., ASP, TF,AL, etc.) are required to obtain 4 mg/L of DO standards.

The effluent from WSP is suitable for irrigation, thus,if 50 % of the effluent could be used for irrigation nearthe immediate vicinity of the treatment plant site, thenhigher DO standards of 4 mg/L can also be achieveddue to the lesser pollution load entering into the river(Fig. 10b).

5.5 A-5: Constructed Wetlands

The alternative with the FWS type of constructed wetlandsto treat the wastewater from the city of Lahore to achieve

4 mg/L of DO standards is examined (Fig. 11). The resultsshow that required DO standards can be achieved with thisalternative. Transported wastewater needs to be treated up to80 % CBOD removal and 60 % NBOD removal, with wet-lands receiving primary treated effluent (Table 6).

The wastewater from Shahadra Outfall located along theright side of the Ravi River cannot be transported to thewetland site between Hudiara Drain and QB Link Canal.Deg Drain is also entering from the right side to the riverand also obtains the dilution of UCC. Therefore, the waste-water loads generated from these two point sources arerequired to be considered separately. In this alternative,provision of WSPs at both of these locations is adopted.Thus, at Shahadra and Deg Drains, 85 % DOT can beachieved with WSP. In this alternative, required DO stand-ards of 4 mg/L can be achieved and the effluent can also beused for irrigation purposes.

6 Evaluation of Water Quality Management Alternatives

The analyses based on the capital, O&M, and land costs for15 years (2010–2025) of all the alternatives described pre-viously are estimated, and the results are summarized inTable 10. These are tentative estimates and are used to

QRiver = 9.2 m3/spH = 7.4

TRiver = 17oCUn-ionized NH3 = 0.78% of total NH3-NNH3-N removal = 80%

Kan = 0.05day-1

0.00

0.01

0.02

0.03

0.04

0.05

20 40 60 80 100

Distance (Km)

Un

-ion

ized

NH

3-N

(mg

N/L

)

Un-ionized Ammonia


Un-ionized NH3 standard = 0.02mg/L

QRiver = 9.2 m3/spH = 7.4

TRiver = 17oCUn-ionized NH3 = 0.78% of total NH3-NNH3-N removal = 90%

Kan = 0.05day-1

0.00

0.01

0.02

0.03

0.04

20 40 60 80 100

Distance (Km)

Un

-ion

ized

NH

3-N

(mg

N/L

)

Un-ionized Ammonia


Un-ionized NH3 standard = 0.02mg/L

(a)

(b)

Fig. 7 a Un-ionized ammonia levels in Ravi River at MA7CD in the future year 2025 with 80 % ammonia removal. b Un-ionized ammonia levelsin Ravi River at MA7CD in the future year 2025 with 90 % ammonia removal


evaluate different alternatives. A graphical representation ofthe summary of cost analysis is shown in Fig. 12.

The cost analysis of A-1 shows that, due to extreme low-flow conditions in the Ravi River, even to achieve 2 mg/L ofDO standards, 346,731 million Rs are required (Fig. 4).From 2 to 4 mg/L, 30 % more cost (454,530 million Rs)

in terms of the removal of BODU (CBODU+NBODU) loadis required (Table 10). However, required un-ionized am-monia standards of 0.02 mg/L can be achieved with 95 %CBOD and 90 % ammonia removal, which means attainingDO standards of 5 mg/L rather than 4 mg/L (Figs. 4 and 7).Energy requirements of ASP are higher than all the other

SIPHON

98.7KM


SHAHADRA GS

26.8KM





RAVI RIVER

Deg Drain(63KM)


QB Link Canal(85KM)

BALLOKI HW

0.0KM

Deg DrainUCC Canal

ASP WASTEWATER TREATMENT PLANT

Degree of treatment = 0%Flow augmentation = 416 m3/s

0

2

4

6

8

10

0 20 40 60 80 100Distance (Km)

DO

(m

g/L

)

Min DO standard = 4mg/L


Flow Augmentation = 210 m3/s

0

2

4

6

8

10

0 20 40 60 80 100Distance (Km)

DO

(m

g/L

)

Minimum DO Standard = 4mg/L

Degree of treatment = 80%Flow Augmentation = 19 m3/s

0

2

4

6

8

10

0 20 40 60 80 100Distance (Km)

DO

(m

g/L

)

Minimum DO standard = 4mg/L

Fig. 8 Simulations to determine the required flow augmentation to achieve 4 mg/L DO


alternatives. There will be a need of skilled labor during theO&M phase, which can be met by proper training of theO&M staff.

The Ravi River low-flow conditions (i.e., MA7CD) mayrequire a very high DOT, which is a very expensive andenergy-demanding option. In the flow augmentation alter-native (A-2) to maintain 4 mg/L of minimum DO standardswithout any treatment, a huge volume of freshwater(416 m3/s) is required to be diverted from MR Link Canal,which may not be possible under the present state of scarcity

of water in Pakistan. However, the possibility of primarytreatment facilities with an augmented flow of 210 m3/s canbe further investigated (Fig. 8). With 80 % degree of waste-water treatment (346,731 million Rs) and only 19 m3/s flowaugmentation (A-2.2), 4 mg/L of DO can be achievedas compared to 90 % treatment (454,530 million Rs) inthe case of MA7CD (A-1.2). In this way, 4 mg/L DOcan be achieved with about 30 % lower costs than A-1.2 if this extra amount of freshwater could be madepossible.

QRIVER = 9.2 m3/s

SIPHON

98.7KM


SHAHADRA GS

26.8KM




RAVI RIVER


QB Link Canal(85KM)

BALLOKI HW

0.0KM


Deg Drain(63KM)

Deg DrainUCC Canal

COLLECTOR CHANNEL

ASP WWT PLANT

PRIMARY TREATMENT PLANT

River Flow (MA7CD) = 9.2 m3/sDOT at Shahadra & Deg Drain = 85%DOT for Transported WW = 0%

0

2

4

6

8

10

0 20 40 60 80 100

Distance (Km)

DO

(m

g/L

)


River Flow (MA7CD) = 9.2 m3/sDOT at Shahadra & Deg Drain = 85%DOT for Transported WW = 40%

0

2

4

6

8

10

0 20 40 60 80 100

Distance (Km)

DO

(mg

/L)


(a)

(b)

Fig. 9 a Wastewater transportation up to the QB Link Canal confluence point without any treatment. b Wastewater transportation up to the QBLink Canal confluence point with primary treatment


Transportation of wastewater (A-3) from the city ofLahore through collector channels to the confluence pointof QB Link Canal is a cost-effective option (Fig. 8a, b).Overall cost of A-3.1 (184,377 million Rs) with primarytreatment facility before the confluence of QB Link Canal isabout 2.5 times lower than A-1.2 (454,530 million Rs)(Fig. 8a). The required O&M is also less than A-1.2.However, dredging may be needed after 1 or 2 years toclean the collector channel. Without primary treatmentfacility, the cost of A-3.2 (103,163 million Rs) is about4.4 times less than A-1.2 to achieve 4 mg/L DO inRavi River (Fig. 9b). Through this channel, the possi-bility of reusing the transported wastewater for the

irrigation along the channel can also be investigatedwith some lower level of wastewater treatment depend-ing upon cropping pattern and type of crop (should notbe raw vegetables).

WSP as an alternative for WQM of the River Ravi comesout to be a low-cost alternative (Table 10), although the landrequirements are very large as compared to the other alter-natives. It can be seen in Fig. 10 that 3 mg/L DO standardscan be achieved with the WSP technology at a cost of65,819 million Rs, which is about 3.5 times less as com-pared to ASP (A-1.3). Furthermore, the effluent quality issufficiently suitable to meet irrigation water qualityrequirements.

River Flow (MA7CD) = 9.2 m3/sDegree of treatment = 83 %

0

2

4

6

8

10

0 20 40 60 80 100Distance (Km)

DO

(mg

/L)

Min. DO Standards = 4mg/L

QRIVER = 9.2 m3/s

SIPHON

98.7KM


SHAHADRA GS

26.8KM





RAVI RIVER

Deg Drain(63KM)


QB Link Canal(85KM)

BALLOKI HW

0.0KM

Deg DrainUCC Canal

WSP (ANAEROBIC +FACULTATIVE + MATURATION)

River Flow (MA7CD) = 9.2 m3/sDegree of treatment = 83 %

0

2

4

6

8

10

0 20 40 60 80 100Distance (Km)

DO

(mg

/L)

Min. DO Standards = 4 mg/L

(a)

(b)

Fig. 10 a Simulation results of DO management alternative with WSP. b Simulation results of DO management alternative with reuse of 50 % ofWSP effluent


7 Conclusions

Model calculations carried out for WQM of the Ravi Rivershow that removal efficiencies of 85 and 90 % are requiredfor 3 and 4 mg/L DO levels, respectively. To achieve 5 mg/L

of DO standards, high removals of both CBODU andNBODU (95 %) are required.

Ammonia toxicity is also a water quality problem in theRavi River. Un-ionized ammonia standards of 0.02 mg/L forthe survival of fish are being violated even under high-flow

QRIVER = 9.2 m3/s

SIPHON

98.7KM


SHAHADRA GS

26.8KM




RAVI RIVER


QB Link Canal(85KM)

BALLOKI HW

0.0KM


Deg Drain(63KM)

Deg Drain

UCC Canal

COLLECTOR CHANNEL

WSP

PRIMARY WWTP

CONSTRUCTED WETLAND

River flow (MA7CD) = 9.2 m3/s

0

2

4

6

8

10

0 20 40 60 80 100Distance (Km)

DO

(m

g/L

)

Min. DO Standards = 4mg/L

Fig. 11 Simulation results of DO management alternative with constructed wetlands

Table 10 Cost evaluation ofWQM alternatives for the RaviRiver

DOT degree of treatment, PTprimary treatment

Alternative Description Cost (million Rs)

Capital O&M Land Total

A-1: Minimum DOT required at MA7CD River flow

A-1.1 5 mg/L DO stand with 95 % DOT 377,841 216,246 320 594,407




A-2: Flow augmentation (to achieve 4 mg/L DO stand)

A-2.1 416 m3/s river flow with 0 % DOT – – – –

A-2.2 210 m3/s river flow with 40 % DOT 63,949 35,291 116 99,356

A-2.2 19 m3/s river flow with 80 % DOT 216,477 129,963 291 346,731

A-3: Wastewater transportation

A-3.1 4 mg/L DO stand with PT 115,840 67,932 605 184,377

A-3.2 4 mg/L DO stand without PT 63,567 39,084 512 103,163

A-4: Low-cost treatment option

A-4.1 WSP with 3 mg/L DO stand at MA7C 58,630 2,165 10,648 71,443


conditions in the river due to the discharge of untreateddomestic and industrial wastewaters. The simulation resultsshow that 90 % ammonia removal is required to meet thedesired un-ionized ammonia standards. This removal resultsin 5 mg/L DO level in the Ravi River.

A flow augmentation of about 19 m3/s through MR LinkCanal with 80 % of CBOD removal can achieve 4 mg/L DOstandards with 30 % lower cost than the conventional treat-ment cost at MA7CD flow conditions. In case of no waste-water treatment, 416 m3/s of flow augmentation is requiredto achieve 4 mg/L DO standards. The flow that can bediverted from MR Link Canal to the Ravi River will dependon the availability of the water in the River Chenab, down-stream irrigation requirements, and may require remodelingof MR Link Canal as well. Transportation of wastewaterfrom the city of Lahore through collector channels withprimary treatment facility at the confluence point of QBLink Canal is a cost-effective option with about 2.5 timeslower cost than the alternative with ASP at all the outfallsand surface drains. However, issues related to O&M of thechannel including dredging and land required for its right-of-way need to be resolved.

WSP as an alternative for WQM of the Ravi River comesout to be a low-cost alternative, if the desired DO standardsare reduced to 3 mg/L. In addition, it has large land require-ments with associated acquisition problems. In this connec-tion, by reusing about 50 % of the WSP’s effluent forirrigation, 4 mg/L DO standards can be achieved as a resultof reduction in pollution load being discharged into the RaviRiver. However, to meet un-ionized ammonia standards,higher NBOD removals are required, which can only beobtained by conventional ASP. Thus, for highly pollutedrivers with such extreme flow variations as in case of theRavi River, meeting un-ionized ammonia standards canreduce the efforts required to develop CBOD-based wasteload allocations, provided that un-ionized ammonia standards

are established after investigating the threshold toxicity of thefish species living in the river.

Acknowledgments The study was funded by the University of En-gineering and Technology, Lahore as part of a Ph.D. research of thefirst author. The support of the laboratory staff in the sample collectionand laboratory analysis is acknowledged.

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* Minimum DO Standards, ** Primary Treatment

Fig. 12 Summary of costevaluation of different RaviRiver WQM alternatives


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http://dx.doi.org/10.1002/hyp.9528

http://www.leeds.ac.uk/civil/ceri/water/tphe/publicat/pdm/india/india.html

http://www.leeds.ac.uk/civil/ceri/water/tphe/publicat/pdm/india/india.html

http://www.epa.gov/PRD/NRMRL

http://www.epa.gov/PRD/NRMRL

Documents

Evaluation of Water Quality Management Alternatives to Control Dissolved Oxygen and Un-ionized Ammonia for Ravi River in Pakistan