PERFORMANCE AND WASTEWATER QUALITY ASSESSMENT OF EFFLUENT TREATMENT PLANT OF ATTOCK REFINERY LIMITED, RAWALPINDI

Abstract

The current study has been carried out to apprise the water footprint in terms of water consumption and effluent generation and to assess the performance efficiency of an effluent treatment plant (ETP) at Attock Refinery Limited. The samples were analyzed for wastewater quality parameters from raw and effluent (treated) stream, characterized their concentration load and compared with Punjab Environmental Quality Standards (PEQS) and International Finance Corporation (IFC), World Bank guidelines. Current treatment train mainly consists of API separators, DAF and activated sludge process. Grab samples were collected from DAF-inlet and final effluent outfall and tested for physico-chemical and heavy metals using instrumental methods and atomic absorption spectrometer. The parameters analyzed for the wastewater quality assessment were pH, Temperature, TSS, TDS, BOD5, COD, O&G, Phenols, TN, TP, Free Cyanide, As, Hg, Fe, V, Pb, Ni, Cr and Cu. The results indicated that the treatment plant was effective in reduction of some parameters like TDS, TSS, As and Fe while concentration for Phenols, O&G, BOD5, and COD were above the permissible limits of both EPA and IFC, World Bank. Hg, Cu and free cyanide were detected in one effluent sample each whereas V, Pb, Ni, and Cr were undetected throughout the sampling campaign. Efficacy or performance of treatment system was determined based on pollutant reduction to acceptable discharge limits while Pearson’s coefficient determined the correlation among various parameters. The study concluded that some pollutant parameters are being discharged in the Soan water body very close or in excess to the prescribed limits and an optimization of the treatment system is required by installing advanced (tertiary) treatment units.