Integrated ultrafiltration membrane unit for efficient petroleum refinery effluent treatment

Abstract

Petroleum refinery effluent (PRE) needs treatment before discharge. One treatment option is the filtration of PRE through membranes but membranes can be become fouled, reducing their efficiency. This study evaluates the improvement of polymeric ultra-filtration (UF) membrane performance by integrating membrane filtration with a Fenton-flocculation process to treat PRE prior to sending it through the membrane. The results show that the integrated-UF membrane system increased the permeate flux by 50% compared to only using the membrane. Similarly, the integrated system increased the chemical oxygen demand, and the oil and grease removal efficiencies by 55 and 4.23%, respectively. The integrated system was further investigated under different conditions of transmembrane pressure (TMP) (1, 1.5, 2 bar) and cross flow velocity (CFV) (250, 300, 600 mL/min). Using Hermia's model, it was found that the cake formation model controlled fouling regardless of the applied TMP and CFV conditions. The extent of fouling was analyzed and characterised via Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy and energy dispersive spectrometry (SEM-EDS). SEM-EDS demonstrated different morphologies between fresh and fouled membrane, where irregularly distributed microparticles/oil droplets on the membrane surface and pores were dominant in the fouled membrane. The inclusion of the pre-treatment stage is therefore, important for improving polymeric UF membrane performance for treating PRE.