The use of coagulation-direct filtration for secondary municipal effluents reclamation

Tertiary treatment processes are essential for reclamation and reuse of wastewaters. The objective of this work was the examination of coagulation and direct filtration on the reclamation potential of secondary effluents from a municipal wastewater treatment plant. A sand filter was used and its efficiency was examined by measuring the absorbance at 254 nm, COD, turbidity, phosphorus and ammonium nitrogen content of the effluents. The effect of coagulation on removal of pollutants from secondary effluents was investigated by the addition of inorganic salts of iron and aluminium. It was found that the addition of coagulants enhanced the removal of organic matter and phosphorus, but resulted in a higher pressure drop through the filter.