Evaluation of Sand Filter as a Non-conventional Post Treatment of Oil Refinery Wastewater: Effect of Flow Rate

Abstract

This work aims to evaluate the treatment efficiency and feasibility of a sand filter as a post treatment for a primary treated effluent from activated sludge process (ASP) of oil refinery wastewater (ORWW) at different flow rates. There are several factors influencing the treatment efficiency of the used sand filter including; wastewater characteristics, sand media and flow rates. The treatment unit consists of opaque sand filter column fabricated from PVC material. It was fed by a primary treated effluent from ASP of ORWW. The average concentrations of raw ORWW for turbidity, Chemical oxygen demand (COD), Biological oxygen demand (BOD), Total suspended solids (TSS) and phenol were 419 NTU, 409 mgO2/L, 118 mgO2/L, 111 mg/L and 2 mg/L, respectively. The sand filter was operated at three different flow rates namely; 120 L/h, 240 L/h and 360 L/h. The experimental results proved that 240 L/h is the optimum flow rate. The achieved removal values at this flow rate were 79.04%, 55.82% and 63.55 for turbidity, COD and TSS, respectively. The treated permeate complies with the National Regulatory Standards for irrigation and/or safe discharge on water streams after slight disinfection.