Waste water discharge impact modeling with QUAL2K, case study: the Zayandeh-rood River

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1 9th Internatonal Congress on Envronmental Modellng and Software Brgham Young Unversty BYU ScholarsArchve 5th Internatonal Congress on Envronmental Modellng and Software - Ottawa, Ontaro, Canada - July 21 Jul 1st, 12: AM Waste water dscharge mpact modelng wth QUAL2K, case study: the Zayandeh-rood Rver Nader Nakhae Amr Etemad Shahd Follow ths and addtonal works at: Nakhae, Nader and Shahd, Amr Etemad, "Waste water dscharge mpact modelng wth QUAL2K, case study: the Zayandeh-rood Rver" (21). 9th Internatonal Congress on Envronmental Modellng and Software Ths Event s brought to you for free and open access by the Cvl and Envronmental Engneerng at BYU ScholarsArchve. It has been accepted for ncluson n 9th Internatonal Congress on Envronmental Modellng and Software by an authorzed admnstrator of BYU ScholarsArchve. For more nformaton, please contact scholarsarchve@byu.edu.

2 Internatonal Envronmental Modellng and Software Socety (EMSs) 21 Internatonal Congress on Envronmental Modellng and Software Modellng for Envronment s Sake, Ffth Bennal Meetng, Ottawa, Canada Davd A. Swayne, Wanhong Yang, A. A. Vonov, A. Rzzol, T. Flatova (Eds.) Waste water dscharge mpact modelng wth QUAL2K, case study: the Zayandeh-rood Rver Nader Nakhae (1), Amr Etemad Shahd (2) (1) Nader_Nakhae@cvleng.ust.ac.r (2) etemad@ust.ac.r Abstract: One of the most sgnfcant hydrologcal resources are rvers (especally for drnkng water). Stream smulaton or modelng s a common cost-effectve way for water qualty montorng and predctng the future qualty of rvers and streams. Ths paper descrbes and demonstrates the applcaton of the U.S envronmental protecton agency s water qualty model, QUAL2K, to The Zayandehrood Rver, one of the bggest Rvers n Iran and Mddle East, and also a way to ncrease dssolved oxygen n order to optmze the water qualty, smulaton of affxng a wer and even more. Frst of all, the rver s hydraulc factors such as roughness are precsely calbrated and subsequently wth the frst set of data accordng to bochemcal oxygen demand and dssolved oxygen the model s calbrated. In the next step along wth above mentoned calbraton, valdaton s done wth the second set of data. Afterwards to fnd out f wers wll amelorate water qualty, a crtcal condton appled wth 2% ncrease n loads whch enforced to the model to smulate effect of wers on the water qualty n ths predcament. Investgaton of results n calbraton and especally valdaton showed that zayandehrood s water qualty s poor downstream of ndustral areas due to waste water dscharges and dssolved oxygen s even under 5 mg/l n downstream hence bochemcal oxygen demand s hgh downstream of ndustral plants. On the other hand smulatng affect of wers n crtcal condtons ndcates that ths method wll ncrease dssolved oxygen (DO) downstream of the wer. Key words: QUAL2K, Local oxygenaton, Zayandehrood Rver, Wer 1. INTRODUCTION: A bg amount of agrcultural, muncpal and ndustral wastewaters dscharges to water bodes around the world. These dscharges of degradable wastewaters n water bodes result n decrease n water qualty generally and partcularly DO (Dssolved Oxygen) concentratons. Accordng to above mentoned problems of wastewater dscharges, t s mportant to manage the water qualty of hydrologcal sources and predct the mpact of contamnants on them. Rvers and streams are one of man sources that suffer a bg amount of pollutant loads and wastewater around the world. Mathematcal models are a way to descrbe relatons between waste loads and water bodes and to descrbe concentraton of each contamnant due to the recevng water body s characterstcs. One of wdely used mathematcal models for streams and rvers s USEPA s QUAL2E- UNCAS (Brown and Barnwell, 1987). Several nadequateness of Q2E has been reported durng these years whch lead to developng a new verson. Qual2k s the newest verson of Qual seres whch developed to cover lmtatons of prevous versons. Although, Qual2k s lmted n smulatng streams and rvers qualty n a one-dmensonal steady state condton, t ncludes DO nteracton wth fxed plants and t taken bottom algae nto account wth CBOD (Carbonous Bochemcal Oxygen Demand).

3 A water qualty modelng study on The Nakdong Rver n Korea performed by both Qual2k and Qual2e, dsplayed that the latest verson of these seres were more accurate due to feld measurements than the former one (Park and Lee, 21). Another applcaton of Qual2k for water qualty modelng n The Bagmat Rver showed that, the model represented the feld data pretty accurate. In ths study varous water qualty management optons taken nto account to control DO, such as polluton loads modfcaton and local oxygenaton (by affxng wers). Apparently local oxygenaton s effectve n rasng DO levels (Kannel et al, 26). The Qual2k can not take groundwater contrbuton of stream nto account. Therefore, n some cases contamnant s concentraton underestmates (Azzellno et al, 26). The Zayandehrood Rver, located n hearth of Iran, s smulated wth Q2K model. A former study wth Q2E whch appled on The Zayandehrood Rver showed that ndustral, muncpal and agrcultural wastes decrease the concentraton of DO and ncrease concentraton of CBOD n some reaches. However, t has been reported that lack of hydraulc data and naccurate qualty measurements was a problem. In ths report The Rver had been dvded nto 8 reaches (Abrshamch et al, 25). The QUAL2K has been chosen for ths study because; the flow condton s almost steady n The Zayandehrood Rver. However, few studes have reported on smulatng the water qualty of The Zayandehrood Rver, but, there s lttle nformaton avalable on gvng qualty control management optons. Another advantage of ths nvestgaton s that The Rver s separated n 18 reaches whch s more detaled and accurate n compare wth former studes. In ths study wth two sets of more detaled hydraulc data and relatvely more accurate feld measurements data of DO and CBOD that are newer than prevous studes on ths case, the Rver frst and foremost has been calbrated and then valdated. Due to poor condton of water qualty whch have been generated from frst step (low DO concentraton), t s necessary to control the stuaton wth performng dfferent ways of management n order to prevent the qualty from worse stuatons. A way that appled n ths smulaton s local oxygenaton wth wer whch has been a good choce for mprovng water qualty levels by ncreasng the amount of DO. The man purposes and objectves n ths nvestgaton were: to test the model s ablty on smulatng stream s qualty, to dagnose wastewater dscharges mpact on streams, to take the affect of local oxygenaton nto consderaton. 2. STUDY AREA AND METHOD 2.1 Study Area The Zayandehrood Rver s one of the bggest rvers n Mddle East whch located n the center of Iran around Isfahan cty. It emanate from Dmeh sprng whch s located wthn 14 km dstance from Isfahan. The rver s length s about 36 km wth a dranage area around 2 42 km (Fgure 1). From The Zayandehrood Reservor an adjusted flow s releasng and tll Kaleh Brdge t s clean because of mountanous area and also due to no dscharge. Water flows n a valley n ths reach and agrcultural farms are not dstrbuted n these parts.

4 Fgure 1- The Zayandehrood Rver locaton and dranage area As above mentoned condton, water wll stay clean untl Kaleh Brdge but after ths area varous pollutant loads are dscharges to rver and the qualty becomes really poor. Afterwards, the Zayandehrood Rver wll flow toward the Varzaneh vllage and after that t wll dvde nto several branches and run through Ghav-khoon Swamp and fnally drans nto t. There are so many bg and small ndustral plants that pollute the rver drectly or ndrectly. Not only they dscharge ther waste wth an ncomplete treatment nto the rver, but also, Bunch of them dscharges ther raw waste. In parallel wth above mentoned dscharges, some other plants may not dscharge ther waste nto the rver but the contamnants may leak to the rver by pollutng the ground water sources. There are several ctes and vllages along the rver whch dscharge ther raw or partally treated wastewater nto the rver (Abrshamch et al., 25). The Abshar Treatment plant whch located n east of Isfahan cty dscharge muncpal wastewater of Isfahan and some other smaller ctes around after treatment but ths plant s output s poor because of low capacty as some tmes raw waste dscharges to the rver. From ths pont onwards the qualty of water begns to decrease rapdly as DO concentratons become low and CBOD rse. These problems and Zayandehrood Rver s vtal role ndcate that a water qualty management requred for ths stuaton n order to predct the future qualty and also to mpede the water qualty of gettng worse. 2.2 Modelng tool In The Qual2k model the Rver wll be dvded nto several reaches and each reach wll be dvded nto equal segments. These segments are model s shortest parts of smulaton. Ths model can smulate fate and transport of so many parameters and contamnants such as temperature, BOD, DO, phytoplankton, varous knds of nutrents, PH and etc. Qual2k has a general mass balance equaton (1) for a consttuent concentraton C n a water column of reach :

5 dc dt Q V Q Q E 1 ab, 1 c c c ( c c ) ( c c V VI V V ) E W V S m 3 m 3 ), V = Where Q = Flow at reach ( ), s Q = Abstracton flow at reach ( ab, s Volume of reach (m 3 mg ), W = Loadng of pollutant to reach ( ), s S = Sources and mg. s snks of the pollutant ncludng reactons and mass transfer ( 3 ), m =Dsperson E m 3 coeffcent between reaches and +1 ( s ), E Dsperson coeffcent between 1 reaches -1and ( m 3 ) and t= tme (s). s 2.3 Method The Zayandehrood Rver has been dvded nto 18 reaches accordng to feld measurements of the Rver s characterstcs. All the reaches are dvded nto several elements whch they are roughly 1km each. Actually, there are 9 measurng ponts that measure the Rver s characterstcs: depth, wdth, velocty and flow (Table1). Destnaton between each of these ponts s consdered as two reaches that the slope of these two are equal but rvers wdth n them are dfferent due to mentoned measurng ponts. There are two set of data from dry and wet season whch appled to calbrate and valdate the model. After these two steps, a 2 percent ncrease wll be appled to waste loads because; t wll help the modelng to be more realstc about future populaton and also ndustral and agrcultural development around Isfahan cty. Wth ths condton appled to the model a crtcal scenaro wll be smulated. From ths part onwards, water qualty management opton (local oxygenaton) wll be taken nto account. Reach\ Measurng pont upstream Length Wdth Slope (km) (m) 1\Tanzm \Zamankhan \Kaleh \Dzcheh \Lenj \Moosan \Choom \Shahkaram \Varzaneh Table 1- Reaches and measurng ponts wth detals

6 3. RESULT AND DESCUSSION 3.1 Model calbraton The model has been calbrated wth feld measurements data of January 23 whch was a dry weather season n ths nvestgaton. Frst of all as long as the Q2K model needs all parameters of the Manng formula, t s necessary to calbrate the manng factor (n. roughness). In order to do so, wth avalable data of flow and depth of measurng ponts at January 23 the Hydraulc calbraton has been appled and estmated roughness of each reach has been calculated. Afterwards, accordng to DO and CBOD feld measurements of January 23, the model has been calbrated. An acceptable match of model and feld data can be seen. The result showed after Kaleh brdge that ndustral loads dscharge to The Rver, DO concentraton starts to drop slghtly (Fgure 2),whle, BOD concentraton undergo a sharp ncrease (Fgure 3). The model has been underestmated the DO concentraton. As t has been mentoned, t happened n former studes n dry weather season because of underground water contrbuton DO(mgO2/L) DO (mgo2/l) data Do mg/l Fgure 2- DO concentraton (mg/l) January 23 (Calbraton ) CBODf (mgo2/l) CBODf (mgo2/l) data 25. BOD mg/l Fgure 3- BOD concentraton (mg/l) January 23 (Calbraton ) 3.2 Model valdaton The next step s to verfy the model wth calbrated parameters. In order to do so another set of data from August 24 (wet weather season) has been appled to the model. DO and CBOD smulaton n ths part showed a pretty good match wth measured data. Same as calbraton, a gradual reducton n DO concentraton s happenng after kaleh area (Fgure

7 3), hence, CBOD amount s gong up dramatcally after ths area (Fgure 4), all because of bg amount of muncpal, agrcultural and partcularly ndustral loads. As t can be seen the Do concentraton s under 5 mg/l n roughly half of rver s length whch s really poor. Ths amount of DO s not sutable even for fsheres survval and t s n class 3 of USEPA s surface water qualty classfcaton. Ths class of water qualty can only be use for agrcultural purposes DO(mgO2/L) DO (mgo2/l) data 8 DO mg/l Fgure 4- DO concentraton (mg/l) August 24 (Valdaton ) CBODf (mgo2/l) CBODf (mgo2/l) data 25. BOD mg/l Fgure 5- BOD concentraton (mg/l) August 24 (Valdaton) 3.3 crtcal stuaton scenaro To estmate future qualty of the rver, at ths step, 2 percent ncrease s appled to all loads and from 182 km from downstream of The Zayandehrood Rver, DO concentraton s under 5 mg/l whch s n class 3 of USEPA s mentoned classfcaton (agrcultural purposes only). To solve ths problem and to ncrease water qualty, local oxygenaton s consdered as a soluton. 3.4 qualty control management opton: local oxygenaton To control ths knd of stuatons an opton that consdered n ths study s local oxygenaton. The goal s to ncrease DO concentraton to more than 5 mg/l accordng to mentoned classfcaton and 7 wers have to be affxed to The Zayandehrood Rver to acheve ths goal (Fgure 6). The type of wer that has been chosen to smulate s regular step. Detals of each wer can be seen n (Table 2).

8 DO mg/l Fgure 6- DO concentraton wth 2% ncrease of loads and local oxygenaton. From 6km of The Rver, because of low flow and velocty, several wers needed to move DO concentraton up to 5 mg/l. heght of each wer s approxmated due to upstream and downstream depth of the wer s locaton to have an optmum output. Wer Locaton (Km) Heght (m) 1- Regular step Regular step Regular step Regular step Regular step Regular step Regular step 4.5 Table 2- wer detals Apparently, Local oxygenaton s an acceptable way to mprove water qualty n streams and t can help rvers to endure bgger loads of degradable wastewater snce DO amount s more. 4. CONCLUSSION Water qualty management has become a serous anxety for envronmental engneers. Wastewater dscharges to water sources s clmbng up these days and ths stuaton s n desperate need of control and management. Qual2k modelng software s a common mathematcal model to control water qualty of streams. Ths model has been used to smulate DO and BOD concentraton n The Zayandehrood Rver n Iran. Calbraton and valdaton that appled wth feld measurement data, demonstrate that ths Rver has been n a poor qualty condton and needed some management opton. However, Qual2k n calbraton and valdaton procedure showed that ths model s perfectly relable n modelng Streams when detaled and complex data are not avalable due to acceptable match wth measured data. To be more realstc about future condton, 2 percent ncrease appled to waste loads whch s an acceptable rase due to populaton ncrease and ndustral development. Ths crtcal scenaro leads to local oxygenaton n order to ncrease water qualty. 7 wers have been smulated to move DO concentraton up to at least 5 mg/l. ths nvestgaton performed that local oxygenaton can be an authentc opton for water qualty management. 5. REFRENCES

9 A.Azzellno, R.Salvett, R.Vsmara, L.Bonomo, 26, Combned use of the EPA-QUAL2E smulaton model and factor analyss to assess the source apportonment of pont and non pont loads of nutrents to surface waters. Scence of total envronment 371 (26) A.Abrshamch, M.Tajrshy, P.Shafean, 25,Uncertanty analyss n qual2e model of zayandehrood rver, water env research 77, 279(25) Brown, L.C., Barnwell, T.O., The Enhanced Stream Water Qualty Models QUAL2E and QUAL2E-UNCAS (EPA/6/3-87-7). U.S. Envronmental Protecton Agency, Athens, GA, 189 pp. Chapra, S.C., Surface Water Qualty Modelng. McGraw-Hll, New York. Haghgh.M.R, A.Abrshamch, Ebolghasem, Ghoresh, 1997, Water qualty assessment and polluton sources of zayandehrood rver, techncal report, sfahan unversty of tech. Prakash Raj Kanne,, S. Lee,, Y.-S. Lee, S.R. Kanel, G.J. Pelleter 25, Applcaton of automated QUAL2Kw for water qualty modelng and management n the Bagmat Rver, Nepal, ecologcal modellng 22 (27)-517 Seok Soon Park, Yong Seok Lee,22, A water qualty modelng study of the Nakdong Rver, Korea, Ecologcal Modellng 152 (22) 65 75