XVII th World Congress of the International Commission of Agricultural and Biosystems Engineering (CIGR)

Transcription

1 XVII th World Congress of the Interntionl Commission of Agriculturl nd Biosystems Engineering (CIGR) Hosted by the Cndin Society for Bioengineering (CSBE/SCGAB) Québec City, Cnd June 13-17, 2010 RIPARIAN CONSTRUCTED WETLADNS FOR IMPROVING WATER QUALITY IN A POLLUTED RIVER IN SOUTHEASTERN MEXICO HERNÁNDEZ, M.E., RUIZ-ENZÁSTIGA P. 1 Biotechnologicl Mngement of Resources Network. Institute of Ecology. Crreter Antigu Cotepec # 351, El Hy, C.P , Xlp, Vercruz Mexico.elizbeth.hernndez@inecol.edu.mx CSBE Presented t ABSTRACT Sordo River is hevily polluted strem becuse it receives untreted urbn sewge. Riprin Constructed wetlnds CW re n dequte lterntive to improve wter qulity in polluted rivers in developing countries. The objective of this study ws to compre the efficiency of surfce flow wter CW (SSFCW) nd subsurfce flow CW (SFCW) to improve wter qulity in the Sordo River. The CW cells mesured 1.5 m length, 0.25 m wide nd 0.6 m depth, four cells were set up for SFCW (uplnd soils, 0.4 m deep, free wter flow column of 10 cm) nd four for SSFCW (volcnic grvel 0.04 m dimeter, 0.4 m depth, wter flow 10 cm below surfce). Two cells of ech type were plnted with Typh sp nd two cells were left without plnts s controls, hydrulic retention time ws 5 dys. From June to November 2009, concentrtion of mmoni nitrogen (N-NH 4 ) in the river wter rnged from 2-18 mg L -1, Chemicl Oxygen Demnd (COD) rnged from mg l -1, Phosphtes (P-PO 4 ) rnged from mg L -1 nd nitrtes (N-NO 3 ) rnged from 0.5 to 7 mg L -1. Both, SSFCW nd SFCW were efficient in P-PO 4 removl (63-93%) but the SSFCW without plnts ws significntly less efficient (20-83%). COD removl efficiency ws similr in SSFCW nd SFCW (27-51% nd 28-73% respectively) nd only the SFCW without plnts showed significntly lower efficiencies (21-45%). For N-NH 4, SSFCW showed significntly higher removl efficiencies (48-95%) thn SFCW (9-70%). It ws concluded tht SSFCW re n ecologicl lterntive to improve wter qulity in this river. Keywords: wter pollution, eutrophiction, strem restortion, sewge INTRODUCTION In Ltin Americ, only 14 % of the totl wstewter receives tretment (Mrtijn y Redwood, 2005). The Mexicn Generl Lw for Environmentl Equilibrium ws encted in 1988 nd wter dischrge regultions were published in However, becuse of the lck of lw enforcement nd the economic crisis, severl rivers in the country re hevily polluted from both industril nd domestic wstewters (Alvárez et l, 2006). Currently, river pollution is country wide environmentl problem tht still needs to be solved. Within this context, it is necessry to find ecologiclly nd economic lterntives to tret both point source pollution nd non point source pollution, in order to improve wter qulity in Mexicn rivers. CIGR XVII th World Congress Québec City, Cnd June 13-17,

2 Constructed wetlnds (CW) re n dequte lterntive to improve wter qulity. Compred with conventionl wstewter tretments, CW re more economicl, they need less mintennce, they do not consume fossil fuels; they show flexibility for treting severl types of wstewter nd different pollutnts lodings (Kdlec, 1996). In ddition, CW provide good esthetics (Brix, 1997). There re two types of CWs, the surfce wter flow CW (SFCW) where wter flows bove the substrte nd the subsurfce CW, where the wter flows below the surfce substrte. Both types of CWs hve been pplied successfully to improve wter qulity nd the criteri for choosing the type of CW, depends of the lnd vilbility, pollutnt loding nd the vilble funding. The cost of SSFCW might be 1.6 higher thn SFCW (Knight, et l., 2003). CWs hve been successfully used to tret point source nd non point source pollution in developed countries (Greenwy nd Wooley, 1999, Kovsic et l., 2000, Vymzl, 2001, Belmont nd Metclfe, 2003, Mikls, 2007). More recently, CWs hve been investigted to improve wter qulity in polluted rivers in developing countries in Asi (Jin, et l, 2001, Kim, et l., 2006, Run et l., 2006, Jung nd Chen, 2007).In Ltin Americ, despite of the multiple benefits tht CWs provide, they hve been less pplied thn in Europe nd USA (Vymzl nd Kropfelov, 2008). We propose the introduction of riprin constructed wetlnds to improve wter qulity in polluted rivers in Mexico. However, the design of these systems in our region still needs mesocosm studies. In this regrds, is importnt to know wht type of CW is dequte to be built in the riprin zones to improve wter qulity. The im of this study ws to compre the COD nd nutrient removl efficiency in SSFCW nd SFCW treting wter from polluted river in southestern Mexico. MATERIAL AND METHODS Study site This study ws conducted in the centrl prt of Vercruz Stte in Southestern Mexico. The mesocosms CW were locted in greenhouse of the Botnicl Grden Frncisco Jvier Clvijero in Xlp (97 01 W N), the cpitl of Vercruz Stte. They were fed with wter from the Sordo River. This river is third order strem tht origintes in the tropicl mountin rinforest upstrem from the botnicl grden, downstrem, it joins the Pixquic River nd finlly it merges to L Antigu River which flows into the Gulf of Mexico. The re of L Antigu river wtershed is 2827 Km 2 (Cstro-Fontn, 2004). Mesocosm CWs The experimentl rry of CW cells (1.5 m length, 0.25 m wide nd 0.6 m depth) ws s follows: four cells were set up for SFCW (substrte uplnd soils, 0.4 m deep, free wter surfce flow column of 10 cm) nd four for HSSFCW (volcnic grvel 0.04 m dimeter, 0.4 m depth, wter flow 10 cm below surfce). Two cells of ech type were plnted with Typh sp nd two were left without plnts s controls. CWs were fed with wter from the river, which receives untreted urbn sewge nd industril wstewters. Wter ws pumped to 500 L homogeniztion tnk nd its flow rte ws djusted for ech cell to hve Hydrulic Retention Time (HRT) of 5 dys. Smpling nd nlyticl methods CIGR XVII th World Congress Québec City, Cnd June 13-17,

3 200 ml wter smples were tken in the homogeniztion tnk (immeditely fter wter ws pumped from the river) nd in the outlet of ech CW cell. Wter smpling ws performed twice week from June to November Chemicl Oxygen Demnd (COD) ws mesured using the oxidtion of K 2 Cr 2 O 7 micromethod (APHA, 1998); mmoni nitrogen ws nlyzed by the Nessler method (APHA, 1998); phosphtes were quntified using the scorbic cid method ccording to Sndell nd Onsh (1978); nitrtes were quntified ccording to Robrge et l. (1983). All these nlyses were performed in unfiltered wter smples. Sttisticl nlyses Sttisticl nlyses were performed with SPSS version 12 for Windows. Kolmogrov- Smirnov, Lilliefors nd Shpiro-Wilk s tests were used to check normlity. The dt fit norml distributions. One wy nlysis of vrince (ANOVA) with Tukey HSD multiple comprison tests were used to investigte significnt differences of COD nd nutrient removl efficiencies mong the tretments. RESULTS AND DISCUSION Plnt growth The increse in plnt height ws very similr in both types of CWs (Figure 1). Typh sp. height incresed from My to July in SFCW nd from My to August in SSCW, fter this, the size of the plnts did not increse. Figure 1. The increse of Typh sp height in constructed wetlnds treting river wter with different type of wter flow. SFCW, Surfce flow constructed wetlnd, SSFCW Subsurfce flow constructed wetlnd; Vlues re men (n=60) Pollutnt concentrtion nd removl COD CIGR XVII th World Congress Québec City, Cnd June 13-17,

4 COD concentrtion in the wter from the Sordo River rnged from 2 to 430 mg L -1 with the higher concentrtions observed in August (Figure 2). COD concentrtions in the effluents of CWs vried during the study period nd sometimes COD concentrtion ws higher in the effluents thn in the river. This is explined by chnges in the redox potentil in the substrte. In uplnd soils nd grvel, iron nd mngnese occur s oxidized forms (Fe +3 nd Mn +4 ) which re insoluble, when soils re flooded, redox potentil decresed nd these ions were reduced to Fe +2 nd Mn +2 which re soluble nd they were wshed out from the wetlnds (Mitsch nd Gosselink 2007). Fe +2 nd Mn +2 re chemiclly oxidized, therefore they contributed to higher concentrtion of COD in the CW effluents. Monthly verge removl percentge of COD rnged from 6 to 82 % (Tble 1), nd no significnt differences were observed between the CWs, except in September when SFCW-C showed significntly lower removl of COD in comprison with the other tretments. Figure 2. COD concentrtion in the river wter nd in the effluents of constructed wetlnds from June to November SFCW, Surfce flow constructed wetlnd; SFCW C, Non-plnted surfce flow constructed wetlnd (control); SSFCW Subsurfce flow constructed wetlnd; SSFCW-C Non-plnted subsurfce flow constructed wetlnd (control). Vlues re verge ± SE (n=2). N-NH 4 CIGR XVII th World Congress Québec City, Cnd June 13-17,

5 Ammoni nitrogen concentrtion in the river rnged from 2 to 18 mg L -1, with higher concentrtion in June nd August. Concentrtion of this ion in the effluents from CWs ws lwys lower thn in the river nd differences mong the CWs were observed. SSFCW showed the highest removl efficiency of mmoni nitrogen, followed by SSFCW-C, SFCW nd SFCW-C (Tble 1). In the SSFCW there were not significnt differences between the plnted nd non plnted microcosm, which indictes tht the removl of mmoni nitrogen in this type of wetlnds involved physicl processes. Figure 3. N-NH 4 concentrtion in the river wter nd in the effluents of constructed wetlnds from June to November SFCW, Surfce flow constructed wetlnd; SFCW C, Non-plnted surfce flow constructed wetlnd (control); SSFCW Subsurfce flow constructed wetlnd; SSFCW-C Non-plnted subsurfce flow constructed wetlnd (control). Vlues re verge ± SE (n=2). The Tiwnese Environmentl Protection Agency, determined tht rivers with N-NH 4 concentrtion higher thn 3 mg L -1 re considered hevily polluted. The recommended concentrtion of N-NH 4 in wter bodies to protect qutic life is 0.5 mg L -1 (Fritz, 1990). According with this, the Sordo River is hevily polluted nd the qutic life in the smpling sttion is in dnger. Tble 1. Averge monthly removl percentge of nutrients nd COD in plnted nd nonplnted wetlnds with different types of wter flow, treting wter from the Sordo River. CIGR XVII th World Congress Québec City, Cnd June 13-17,

6 Month Type of CW Removl % COD N-NH 4 N-NO 3 P-PO 4 June SFCW 27.7 ± ± ± ± 1.7 SFCW-C 21.4 ± ± ± ± 1.5 SSFCW 28.3 ± ± ± ± 1.3 SSFCW -C 26.3 ± ± ± ± 4.1 b July SFCW 11.3 ± ± 15.7 c 63.4 ± ± 22.3 SFCW-C 16.7 ± ± 6.5 b 73.8 ± ± 21.7 SSFCW 18.7 ± ± 8.5 c 60.9 ± ± 21.2 SSFCW -C 22.4 ± ± 12.3 bc 58.9 ± ± 17.3 b August SFCW 51.5 ± ± 7.4 c 59.5 ± ± 0.9 SFCW-C 45.5 ± ± ± ± 1.9 SSFCW 44.4 ± ± 0.6 b 61.8 ± ± 1 SSFCW -C 51.9 ± ± 4.8 b 58.1 ± ± 9 September SFCW 40.5 ± 16.3 b 20.1 ± ± ± 2.3 SFCW-C 21.5 ± 8.8 b 9.4 ± ± ± 1.4 SSFCW 73.2 ± 12.1 c 82.9 ± 3.2 b 76.5 ± ± 1.2 SSFCW -C 82.8 ± 10.2 c 56.5 ± 10.9 b 60.0 ± ± 9.5 b October SFCW 42.3 ± ± 9 SFCW-C 17.1 ± ± 4 b 64.8 ± ± ± ± 1.9 SSFCW 53.4 ± ± 0.7 c 77.8 ± ± 1.7 SSFCW -C 44.7 ± ± 2.8 c 56.5 ± 19 November SFCW 26.3 ± 10.9 SFCW-C 6.1 ± 4.4 SSFCW 43.1 ±13.8 SSFCW -C 37.1 ± 12.6 b 66.5 ± 6.1 b 55.2 ± ± ± ± 5 b 88.9 ± ± ± 0.9 c 84.6 ± ± ± 1.2 c 64.4 ± ± 8.1 b SFCW, Surfce flow constructed wetlnd; SFCW -C Non-plnted surfce flow constructed wetlnd (control); SSFCW Subsurfce flow constructed wetlnd; SSFCW -C Non-plnted subsurfce flow constructed wetlnd (control). Vlues re verge ± SE (n=16).different letters indicte significnt differences between the rows (P < 0.05). N-NO 3 Nitrte-nitrogen concentrtion in the river rnged from 0.5 to 7 mg L -1, showing the highest concentrtion in July (Figure 4). Removl efficiency of this ion ws not CIGR XVII th World Congress Québec City, Cnd June 13-17,

7 significntly different mong the two types of CWs. The US Environmentl Protection Agency (EPA) hs since dopted the 10 mg L -1 (Reilly et l, 2000) stndrd s the mximum contminnt level (MCL) for nitrte-nitrogen, thus, N-NO 3 in the Sordo river is not importnt contminnt. Figure 4. N-NO 3 concentrtion in the river wter nd in the effluents of constructed wetlnds from June to November SFCW, Surfce flow constructed wetlnd; SFCW C, Non-plnted surfce flow constructed wetlnd (control); SSFCW Subsurfce flow constructed wetlnd; SSFCW-C Non-plnted subsurfce flow constructed wetlnd (control). Vlues re verge ± SE (n=2). P-PO 4 Phosphte concentrtion in the river rnged from 0.5 to 5 mg L with the highest concentrtions in June nd August. Concentrtions in the effluents from CWs were lwys lower thn in the river (Figure 5).Removl percentge of this ion rnged from 21 to 97% nd ws the SSFCW-C systems tht showed significntly lower phosphte removl efficiency. This indicted tht when the substrte ws grvel, plnts hve n importnt role in the removl of this ion. However when the substrte ws soil, the removl ws similr in plnted nd non plnted CWs, which indicted tht in SFCW, phosphtes were removed by physicl methods such s dsorption. A concentrtion of mg L -1 is recommended to void eutrophiction in wter bodies (Wetzel, 1981).Phosphte concentrtion in the Sordo River is thousnd times higher thn the recommended vlue, nd CWs were ble to decrese the concentrtion to cceptble levels. CIGR XVII th World Congress Québec City, Cnd June 13-17,

8 Figure 5. P-PO 4 concentrtion in the river wter nd in the effluents of constructed wetlnds from June to November SFCW, Surfce flow constructed wetlnd; SFCW C, Non-plnted surfce flow constructed wetlnd (control); SSFCW Subsurfce flow constructed wetlnd; SSFCW-C Non-plnted subsurfce flow constructed wetlnd (control). Vlues re verge ± SE (n=2). CONCLUSION The Sordo River is hevily polluted by domestic wstewter ccording with the concentrtions of COD, N-NH 4 nd P-PO 4. Constructed wetlnds decresed N nd P loding in the river wter. SSCWs were more efficient in mmoni nitrogen removl thn SFCWs. Acknowledgements. Funding for this project ws provided by the Mexicn Ntionl Council for Science nd Technology-CONACYT through the Ntionl Reserch System-SNI-Undergrdute project # nd the Bsic Science project # The uthor thnks to the Botnicl Grden Frncisco Jvier Clvijero the support provided. REFERENCES Álvrez,J.P.A.,J.E.R. Pnt, C.R. Ayl, nd E.H. Acost Índice de Clidd del gu en l cuenc del Rio Amjc, Hidlgo, México: Dignóstico y predicción. Revist Interncionl de Botánic, 75:71-88 APHA, Americn public Helth Assocition, 3er edition Stndrd Methods for the Exmintion of Wter nd wstewter. Wshington, D.C. APHA-AWWA-WPCF. Belmont, M.A. nd C.D. Metclfe Fesibility of using ornmentl plnts (Zntedeschi, ethiopic) in subsurfce flow tretment wetlnds to remove nitrogen, chemicl oxygen demnd nd nonyphenol ethoxylte surfctnts lbortory scle study. Ecologicl Engineering 21: CIGR XVII th World Congress Québec City, Cnd June 13-17,

9 Brix, H Do mcrophytes ply role in constructed wetlnds tretments. Wter Science nd Technology 5 (5): Cstro-Fontn, D.G Gis nd cloud forest conservtion in Mexico: connecting GIS nd strem visul ssessment protocols. Mster thesis. Royl Institute of Technology, Stockholm, Sweden. pp 8 Frits, V.L The Wter Encyclopedi. Lewis Publishers Greenwy M. nd A. Woolley Constructed wetlnds in Queenslnd: performnce efficiency nd nutrient bioccumultion. Ecologicl Engineering 12: Jing, S.R. Y.F. Lin, D.Y Lee nd T.W. Wng Nutrient removl from polluted river wter by using constructed Wetlnds. Bioresource Technology. 76: Jung D.F. nd P.C. Chen Tretment of polluted river wter by new constructed wetlnd. Interntionl Journl of Environmentl Science Technology, 4: Kdlec, R.H. nd L.R. Knight, 1st edition Tretment Wetlnds. Ann Arbor, MI: Lewis Publishers Inc. Kim S.J., S.W. Hong Y.S. Choi W.K. Be nd S.H. Lee An innovtive constructed wetlnd system for smll strem wter restortion. Wter Prctice & Technology, (1) 2: Knight, R.L., W.E. Wlton, G.F.O. Moreir, W.K Reisen nd R. Wss Strtegies for effective mosquito control in constructed tretment wetlnds. Ecologicl Engineering, 21: Kovcic, D., A.M.B. Dvid, L.E. Gentry, K.M. Strks nd R.A. Cooke Effectiveness of constructed wetlnds in reducing nitrogen nd phosphorus export from griculturl tile dringe. Journl of Environmentl Qulity, 29, Mrtijn, E. nd M. Redwood Wstewter in devoliping countries- limittions for frmers to dopt pproprite prctices. Irrigtion nd Dringe. 54: Mikls, S., Hrrington, R., Crroll, P. nd Mustf, A The integrted constructed wetlnds (ICW) concept. Wetlnds, 27, Mitsch, W.J. nd J. Gosselink, 4th edition Wetlnds. John Wiley nd Sons Inc. Nuev York 581pp. Reilly, J.F., A.J. Horne nd C.D. Miller Nitrte removl for drinking wter supply with lrge free-surfce constructed wetlnds prior to groundwter rechrge. Ecologicl Engineering 14: Rofrge E. nd Jonson B Wter nd wste wter nlysis for nitrte vi nitrttion of slicylic cid. Communiction in Soil Science nd Plnt Anlyzes 14(12): Run, X., Y. Xue J. Wu L. Ni M. Sun nd X. Zhng Tretment of Polluted River Wter Using Pilot-Scle Constructed Wetlnds. Bulletin of Environmentl Contmintion nd Toxicology. 76: CIGR XVII th World Congress Québec City, Cnd June 13-17,

10 Sndell, E. nd H. Onish Photometric determintion of trces of metls. John Wiley nd Sons Inc. USA. p Vymzl, J Constructed wetlnds for wstewter tretment in the Czech Republic. Wter Science nd Technology) 11-12): Vymzl, J. nd L. Kropfelov, 1st edition.2008.wstewter tretment in constructed wetlnds with horizontl sub-surfce flow. Springer. The netherlnds Wetzel, R., 1st edition Limnologí..Omeg. Brcelon, Espñ. 679 pp. CIGR XVII th World Congress Québec City, Cnd June 13-17,