EVALUATION OF GREEN HOUSE GASES EMISSIONS FROM SEWAGE TREATMENT PLANTS IN DELHI

Abstract

Sewage treatment plants are considered as sources of GHGs (greenhouse gases) production mainly methane, carbon dioxide and nitrous oxide which are produced during biological sewage treatment process and off-site electricity production which is a major source of CO2 generation. Reducing the green house gases from the sewage treatment plants is a major concern. The day to day increase in the global temperature is an alarming situation and the most prominent cause of which is increase in the emission of green house gases. In this study, it has been attempted to evaluate the emissions of green house gases from some of the major sewage treatment plants of Delhi. It has been observed that the indirect GHGs emission because of the generation of power at off-site is much more than the direct on-site GHGs emission as a result of sewage treatment by the Activated Sludge Process. The power consumption of the concerned plants are obtained the respective plants. The total power consumption of Okhla, Keshopur and Yamuna Vihar sewage treatment plants are obtained by the addition of the BSES electricity bills for each month(January-2014 to December-2014) provided by the engineers at the respective plants. The power consumption includes the power consumed by all phases i.e. the six phases of Okhla plant, three phases of Keshopur plant and two phases of Yamuna Vihar plant. The Keshopur STP has the highest GHGs emissions of 18640 tCO2/yr and emissions from Yamuna Vihar sewage treatment plant is lowest at 4159 tCO2/yr. Although the plants are centralized and well managed but in case of power failure there is no back up. The highest emissions from Keshopur STP is due to more power consumption for operating various operational units as compared to other sewage treatment plants. All the calculations are done based on IPCC 2006 guidelines. The direct GHGs from all the four STPs are same as the MCF factor value for all the activated sludge process based treatment plants is same as provided by Delhi Jal Board and by the respective treatment plants.