ASSIMILATIVE CAPACITY OF NAJAFGARH DRAIN, NEW DELHI

Abstract

Water being a renewable source of energy has the capacity to regenerate itself i.e. it has the capability to go under self-purification and can assimilate the loadings upto a threshold level. If the waste loadings increase beyond standard limits, there is a decrease in dissolved oxygen which affects the ecosystem and DO deficit increases and the capacity of the water body to assimilate the organic waste decreases. Keeping in consideration the similar problem, the present dissertation is concerned with the deteriorating assimilation capacity of the River Yamuna (Delhi) which is 22 kilometre stretch. Within this 22 kilometre stretch 18 drains meet the main river and ott which 15 drains were considered (rest under no flow conditions). Streeter Phelps Equation was used to get the BOD profiling of the complete stretch and this done by calculating the changes in the biological oxygen demand after the confluence of drains and variations in biological oxygen demand with respect to distance. DO deficit along the whole stretch was observed in the range 8.57-11.2 mg/i and BOD ranges from 27-51 .7 mg/l and dissolved oxygen is almost nil along the entire length of the river during the lean period. These results ensure that the Delhi segment of River Yamuna has lost its regenerative capacity. Effective measures need to be taken like engineered methods to control the point pollution sources (effluent aeration, direct aeration, augmentation of low flows, engineered structures with algal mats), control methods for non-point sources (improved agricultural practices, accelerated nutrient outflow, constructed wetlands) and ensure implementation of zero discharge policy ( reducing the Coliform content by incorporating the effective tertiary treatment like UV disinfection in the sewage treatmenplant. All these remedial measures will directly/indirectly affect the assimilation capacity and implementation of these measures may help in "Yamuna Rejuvenation".