Journal of Biology and Nature

This study focused on evaluating the performance of a Sewage Treatment Plant (STP) located in Joginder Nagar, Himachal Pradesh. The plant operates using the extended aeration activated sludge process and has a treatment capacity of 1.735 million liters per day (MLD). To understand its efficiency, samples were collected monthly from both the inlet and outlet points of the plant between January and June 2025. These samples were tested for a range of physio-chemical parameters including Odor, Color, Temperature, pH, Free CO_2, Alkalinity, Total Dissolved Solids (TDS), Conductivity, Turbidity, Total Hardness (TH), Calcium, Magnesium, Biological Oxygen Demand (BOD), Chemical Oxygen Demand (COD) and Dissolved Oxygen (DO).  The findings revealed that while the STP moderately reduced turbidity, COD, and TDS levels, and showed some improvement in DO levels, it also exhibited several limitations. Persistent issues such as unpleasant odor, inconsistent BOD levels, and unaltered calcium and magnesium concentrations were observed in the treated effluent which considered to be a big operational challenge. These inconsistencies suggest that the treatment process is only partially successful in bringing the effluent within acceptable quality standards.Overall, the study highlights that although the STP does offer some degree of pollutant reduction, there remains a need for further improvement, especially in terms of biological stability and odor control. With proper upgrades and regular monitoring, the STP can perform more effectively and meet environmental standards and Enhancing the system’s efficiency could help it better comply with Central Pollution Control Board (CPCB) norms and contribute to safer water discharge into the environment.