The removal of phosphates from laundry wastewater using alum and ferrous sulphate as coagulants

Phosphates are derived from a wide variety of sources including the atmosphere, agriculture, urban drainage domestic and industrial wastewater. Domestic and industrial wastewater such as from laundry and dry cleaning services release high concentration of phosphates through detergents used into the land and water environment. This work was aimed at studying the removal of phosphates from laundry wastewater using alum and ferrous sulphate as coagulants for treatment. Samples of wastewater were collected from two laundry companies in Lagos State, Nigeria. The physicochemical parameters measured were pH, total dissolved solids, total solids, total suspended solids, biochemical oxygen demand (BOD), chemical oxygen demand (COD), COD: BOD and phosphate removal. Using ferrous sulphate and aluminium sulphate as coagulants, the phosphates were precipitated from the waste water samples. The results obtained from locations A and B were pH (9.10 and 10.20), total solids (800.00 and 900.00 mg/l), total suspended solids (200 and 400 mg/l), total dissolved solids (600 and 500 mg/l), biochemical oxygen demand (276.70 and 134.00 mg/l), chemical oxygen demand (716.00 and 664.00 mg/l) and phosphate removal (26.0 and 30.0%) respectively. These results were compared with the Federal Environmental Protection Agency limits (FEPA, Nigeria) and found to be higher than the recommended standards. Thus, these results suggested adverse effects on the environment and impairment of the health of aquatic life where such waste water is being discharged. In conclusion, the use of alum in phosphates removal from laundry wastewater provided better results than ferrous sulphate