Application of constructed wetland for rejuvenation of Delhi stretch of River Yamuna

Background/Question/Methods River Yamuna is one of the major rivers of the Indo-Gangetic plain. The rapid industrialization and urbanization has led to large quantity of discharge of untreated industrial waste and sewage this, river Yamuna’s pollution starts from Tajewala around 150 kilometers upstream from Delhi because of numbers of Industrial cities discharging partially treated effluent. Delhi alone contributes to more than 3,500 MLD (923.0 MGD) of sewage through 15 major drains out-falling in Yamuna. The huge quantity of partially treated and untreated effluent falling in Yamuna in its Delhi stretch, along with its low perennial flow has made Yamuna as one of the most polluted rivers of the India. The water quality in most of the stretch of 21 km of river Yamuna in Delhi region can be classified to E category, i.e. not fit for any designated purpose. The gap in the industrial effluent/sewage generated and its treatment has led to a sever deterioration in the quality of Yamuna water. According to a study only 45% of sewage and 55% of industrial effluent are treated up to secondary level before discharge into the river. The Yamuna is almost dead with no major aquatic life and dissolved oxygen. The value of BOD and COD at some places in this stretch of Delhi is reported to be as high as 40 and 175 mg/l, respectively. Fecal Coli forms and Total Coli forms were also reported to be 989*104 and 1700*104 MPN/100ml respectively i.e. approximately 25 times above the prescribed limit. Results/Conclusions A dynamic constructed wetland simulation model which was specially developed for tropical climate has been applied to design constructed wetlands at the discharge points of six major drain contributing 90% of pollution load on Yamuna. According to this study the BOD load on Yamuna can be reduced by 50-60%., if the recommended sizes of constructed wetlands are planned at out-fall of these drains. It is also envisaged that the proposed constructed wetlands will recuperate the river Yamuna and make its water quality fit for aquatic life.