In this study, treatability of wastewaters generated from a water-based paint and allied products industry has been investigated. As the industry already houses a treatment facility that consists of a coagulation-flocculation unit followed by an activated sludge process, the experimental study focuses on using the existing treatment plant in the most efficient way. In this context the COD removal efficiencies and operating costs of different coagulants i.e., sodium bentonite, alum, FeCl3 and FeSO4 have been evaluated. By assessing the refractory COD content of the subsequent activated sludge system outlet, the coagulant yielding the optimal output has been addressed. The outcomes reveal that the optimum result can be obtained by applying 50 mg L-1 of FeCl3 coagulant at the original pH of the effluent.