Treatment of pharmaceutical wastewater (herbal) by a coagulation/flocculation process

Pharmaceutical factory wastewater (herbal nature) poses pollution problem due to its high COD and BOD. Moreover the characteristics of the wastewater depicts wide variation due to variation in the type of medicines manufactured and raw material utilization. Addition of solvents and oils as per the requirement also add to the pollution load. Because of this problems the conventional treatment units which employ activated sludge process (ASP) and trickling filter for the pharmaceutical factory (herbal) effluent treatment usually malfunctions. It was thus proposed to subject the wastewater to physico-chemical treatment, using different coagulants and coagulant aids. Commonly available coagulants like lime, alum, ferrous sulphate, ferric chloride, polyaluminium chloride (PAC) and also polyelectrolyte were studied. Results indicated that this wastewater is amenable to physico-chemical treatment, and can be applied both as a pretreatment technology or as a polishing treatment. Lime : Alum : Polyelectrolyte resulted in good and most economical removals of SS, COD and BOD of 69.75%, 82.51% and 86.72%, respectively, at a dose of 300:100:0.1 mg/l, respectively. The paper discusses in detail the results obtained with other coagulants and their comparative efficiency.