Treatment of Toxic Organics in Industrial Wastewater using Activated Sludge Process

Document Type: Original Research Paper


1 Department of Environmental Studies, Sindh Madressatul Islam University, Karachi, Pakistan

2 Institute of Environmental Studies, University of Karachi, Karachi, Pakistan


In Pakistan besides pesticide contamination from agricultural field, the manufacturing industries
are also contributing relatively high quantities of toxic pesticides into the environment. These pesticides may
be toxic, mutagenic or carginogenic and may be bioaccumulated or biomagnified by the biota. Because of
persistent nature of pesticides, its removal from environmental system become difficult. The effective operation of wastewater treatment plant plays an important role in minimizing the release of toxic compounds into the environment. Research on the removal of toxic organics using the biological treatment plants is limited. In this study the bacterial isolate, IES-PS-1, was used to assess its potential for Cypermethrin degradation in activated sludge process. The experimental findings indicate that by maintaining the optimum operating conditions in the reactor, the removal efficiency significantly improved and > 88 % degradation observed at 80 mg/L dose. However, the complete removal of Cypermethrin, determined by High Performance Liquid Chromatography (HPLC), occurred at 20mg/L during 48 hour treatment. In addition, a considerable reduction in the sludge volume and chemical oxygen demand (COD) was also observed, producing an acceptable effluent quality with stable residual solids. These findings would be valuable in operating the wastewater treatment system for toxic waste removal.