E.K. TETTEH AND S. RATHILAL
Abstract
Acidification-coagulation-dissolved air flotation (DAF) configured pre-treatment process was employed on a laboratory DAF batch process for the treatment of oil refinery wastewater. The key factors such as acidified conditions, pH and coagulant dosage were used to evaluate three different acids. About 75% removal of the contaminants such as chemical oxygen demand (COD),soap oil and grease (SOG), total suspended solids (TSS) and turbidity was achieved. This was attained within pH of 4 to 6, while using Polyaluminium sulphate (PAS) at a coagulant dosage of 5 mg/L and flotation time of 15 minutes. Among the acids investigated, phosphoric acid showed significant efficiency. With phosphoric acid being identified as the effective acid at pH 5, with an increased coagulant dosage from 5 to 10 mg/L, contaminant removal was about 80%.Thus, the process of acidification in advanced oil refinery wastewater treatment is essential, as well as coagulation for effective treatability performance.