Study on Kinetics of Pollutants Removal in Guheshwori Wastewater Treatment Plant, Kathmandu

Settlement in Kathmandu started from riverbanks. With the increase in population, industrialization and various other economic activities, the wastewater generation has increased significantly. The objective of this study is to assess the performance and determine the kinetics of the only functional centralized municipal Wastewater Treatment Plant (WWTP) based on Oxidation Ditch in the capital Kathmandu of Nepal. The removal efficiencies of the Guheshwori WWTP (GWWTP) for Chemical Oxygen Demand (COD) and Biochemical Oxygen Demand (BOD) were found to be 76.12% and 78.51% and 76.13% and 76.18% during pre-monsoon and monsoon period, respectively. The nutrient removal efficiencies considering the phosphate was found to be 47.61% and 55.60% and ammonia-nitrogen was 12.67% and 29.11% during the pre-monsoon and monsoon period, respectively. The current removal efficiencies do not meet the final effluent discharge standards set by the Government of Nepal. The analysis of kinetic values of pollutant removal showed that the yield coefficient (Y), decay coefficient (kd), maximum specific growth rate and saturation constant (Ks) for GWWTP were found to be 0.18 (kg VSS /kg COD) and 0.05 (d-1) 5.26 and 27.26 (mg/l), respectively. These values can be beneficial in upgrading or improving the performance of the plant.