A new combination of microfiltration, powdered activated carbon and coagulation for treatment of oily wastewater

In this paper, home-made mullite and mullite-alumina microfiltration membranes fabricated by extrusion and sintering procedures employed in novel microfiltration-powdered activated carbon-coagulation hybrid process for oily wastewater (or oil-in-water emulsion) treatment. Powdered activated carbon and four types of coagulants: aluminum chloride, aluminum sulfate, ferrous chloride and ferrous sulfate plus equal concentration of calcium hydroxide Ca(OH)(2) was added to the oily wastewater in the hybrid process. Powdered activated carbon was used as adsorbent agent in all tests. All experiments were performed under the best operating condition of cross-flow velocity = 1.5 m s(-1), transmembrane pressure = 3 bar and temperature = 35 degrees C. Total organic hydrocarbon rejection and permeate flux of membranes for each test were reported and discussed. Hermia's models for cross-flow microfiltration were used for prediction of permeate flux reduction with time for both membranes in hybrid process. Average errors between experimental and modeling permeate flux were calculated for each model and compared with the other models. Results showed that by using iron salts, total organic hydrocarbon rejection and permeate flux are higher than aluminum salts for both mullite and mullite-alumina membranes. Cake layer formation is dominant fouling mechanism under all coagulant agents and is in good agreement with experimental permeate flux for mullite and mullite-alumina membranes.