Key performance indicators for evaluating the efficiency of wastewater treatment plant through process performance model

Wastewater treatment facilities mitigate pollutants to comply with the standards established by the regulating bodies. Monitoring of wastewater treatment plants (WWTPs) is essential for maintaining social, environmental, and economic sustainability. The performance of WWTP is generally measured by the percentage removal of key pollutants, which gives a false impression of treatment efficiency, especially for pollutants at low concentrations. The pollutants vary based on many factors, and there is no standardised method for evaluating the efficiency of WWTP in India. The current study focuses on process performance by measuring the output quality. The sewage, after treatment, is separated into two distinct parts: effluent and sludge. Hence, both effluent and sludge quality characteristics are measured to evaluate the process performance. This study explores a systematic methodology for identifying key performance indicators (KPIs) to measure the efficiency of WWTP through process performance for a sustainable future. Biochemical Oxygen Demand (BOD), Chemical Oxygen Demand (COD), Total Suspended Solids (TSS), Total Nitrogen (TN), Total Phosphorus (TP), and Faecal coliform (FC) are identified as robust effluent quality characteristics. In contrast, Nitrogen, Phosphorus, Potassium, Heavy metals, and Faecal Coliform are recognised as sludge quality characteristics. The relative weightage of each parameter is calculated through a questionnaire survey using the Analytic Hierarchy Process (AHP) for its prioritisation. Monitoring KPIs not only improves the plant’s treatment capacity but also promotes sustainability. Further, these KPIs facilitate continuous improvement and support decision-making in wastewater treatment processes.