Coagulation followed by Ion exchange to treat domestic sewage

Abstract

The pollutants contained in domestic sewage (DS) was separated using coagulation in first stage followed by ion exchange (IE) in second stage. The coagulants FeCl3, Alum and Al2(SO4)3.16H2O were used for treatment. Among these, performance of Al2(SO4)3.16H2O and FeCl3 was equally good in term of chemical oxygen demand (COD) removal at their optimum pH and optimum dose. COD values were reduced to 78 and 80 mg/dm3 with Al2(SO4)3.16H2O and FeCl3 from initial value 256 mg/dm3. The FeCl3 coagulant treated DS was further treated using IE process, which was able to reduce hardness upto 10 mg/dm3 from initial value 580 mg/dm3. Settling of FeCl3 treated sludge was found to best and design of settler has been presented from experimental data.