Oily wastewater treatment by adsorption–membrane filtration hybrid process using powdered activated carbon, natural zeolite powder and low cost ceramic membranes

In this research, four types of low cost and high performance ceramic microfiltration (MF) membranes have been employed in an in-line adsorption–MF process for oily wastewater treatment. Mullite, mullite-alumina, mullite-alumina-zeolite and mullite-zeolite membranes were fabricated as ceramic MF membranes by low cost kaolin clay, natural zeolite and α-alumina powder. Powdered activated carbon (PAC) and natural zeolite powder in concentrations of 100–800 mg L⁻¹ were used as adsorbent agent in the in-line adsorption–MF process. Performance of the hybrid adsorption–MF process for each concentration of PAC and natural zeolite powder was investigated by comparing quantity of permeation flux (PF) and total organic carbon (TOC) rejection during oily wastewater treatment. Results showed that by application of 400 mg L⁻¹ PAC in the adsorption–MF process with mullite and mullite-alumina membranes, TOC rejection was enhanced up to 99.5% in comparison to the MF only process. An increasing trend was observed in PF by application of 100–800 mg L⁻¹ PAC. Also, results demonstrated that the adsorption–MF process with natural zeolite powder has higher performance in comparison to the MF process for all membranes except mullite-alumina membranes in terms of PF. In fact, significant enhancement of PF and TOC rejection up to 99.9% were achieved by employing natural zeolite powder in the in-line adsorption–MF hybrid process.