Efficiency of Sequential Batch Reactor (SBR) based sewage treatment plant and its discharge impact on Dal Lake, Jammu & Kashmir, India

Abstract

Dal Lake is the second largest and most beautiful Lake in the state of Jammu and Kashmir and is the major centre of tourist activities. Due to the continuous increase in the population, the generation of domestic wastewater also increased. The present study was carried out to assess the efficiency of Sequential Batch Reactor (SBR) based Sewage Treatment Plant (STP) located at Brari Numbal and its discharge impact on the physicochemical properties of Dal Lake. The sample was collected from the selected sampling sites (inlet and outlet of SBR based STP, upstream, confluence zone, and downstream of Dal Lake) for five months (November 2019 to March 2020) and analysed using the standard methodologies. The plant shows maximum removal efficiency for BOD (79.85%) although the effluent BOD was found above the standard limit. The minimum removal efficiency of the plant was observed in the case of pH (3.46%). The gain in the case of DO was observed +851.55%. All the sites of Dal Lake were found polluted but the confluence zone and downstream were more polluted in comparison to the upstream due to the discharge of STP outlet into Dal Lake with higher BOD and COD (21.39% increase in BOD, 43.29% increase in COD; 80.10% increase in iron, 65.61% increase in ammonical nitrogen, and 101% increase in phosphate concentration). Besides this, discharge of the huge quantity of untreated wastewater from the city into the lake is also responsible for the degraded water quality of Dal Lake. It can be concluded that efficiency of the plant was in moderate condition and it needs further modifications. This is the first study showing the impact of SBR-STP effluent on Dal Lake.