Performance study of mullite and mullite–alumina ceramic MF membranes for oily wastewaters treatment

In this paper, results of an experimental study on separation of oil from actual and synthetic oily wastewaters with mullite and mullite–alumina tubular ceramic membranes are presented. Mullite and mullite–alumina microfiltration (MF) symmetric membranes were synthesized from kaolin clay and α-alumina powder. The effects of different operating parameters such as pressure (0.5–4 bar), cross flow velocity (0–2 m/s), temperature (15–55 °C), oil concentration (250–3000 ppm) and salt concentration (0–200 g/L) on permeation flux (PF), fouling resistance (FR), fouling and rejection (R) of mullite and mullite–alumina membranes for treatment of synthetic wastewaters were investigated. In order to determine the best operating conditions, 250–3000 ppm condensate gas in water emulsions was employed as synthetic oily wastewaters using mullite membrane. At the best operating conditions (3 bar pressure, 1.5 m/s cross flow velocity and 35 °C temperature), performance of mullite and mullite–alumina membranes for treatment of real and synthetic wastewaters were also compared. The results for treatment of emulsions showed that the mullite ceramic membrane has the highest R (93.8%) and the lowest FR (28.97%). Also, the mullite–alumina ceramic membrane with 75% alumina performs high PF (244 L/m2 h) and low R (81.3%). Also for all the membranes, R for the real wastewater is lower than that for the synthetic wastewaters.