Abstract
Physico-chemical and biological approaches were studied on the mixed-industrial effluent running through the closed drainage system (CDS) within an industrial zone and the study was run separately. The mixed-industrial effluent comprised effluents from various industries that have been treated at their own treatment plant system and should have met the regulated limits before discharging into the CDS. But in this case it happened adversely. The aim of this study was to compare the ability of both approaches in treating the mixed-effluent based on the COD removal. The biological study was carried out at 0.5 mg/L dissolved oxygen (DO) concentrations in bench scale activated sludge with the addition of granular activated carbon (GAC), at 4 hours hydraulic retention time (HRT). Inorganic coagulant; Alum and poly-aluminum chloride (PACl) each in combination with three different types of powder activated carbon (PAC) used in the physico-chemical treatment. The experiments were operated at inherent pH of the mixed-industrial effluent. The results for physico-chemical treatment shows that if the pH of the mixed-industrial effluent remains unaltered, a higher dosage of both alum and polyaluminium chloride (PACl) are needed to reduce COD value by 17.5% and 30.2% for PAC type A, 31.5% and 67.4% for PAC type B, 36.1% and 43.6% for PAC type C respectively. The results obtained under suspended-fixed growth system illustrate about 72% of the COD been removed.
