Chemical cleaning of mullite ceramic microfiltration membranes which are fouled during oily wastewater treatment

In this study, chemical cleaning of home-made mullite ceramic membranes which are fouled during oily wastewater treatment was investigated. The high performance and low cost mullite membranes were prepared by local low cost kaolin clay using extrusion method and the characteristic of the fabricated membranes was studied by different methods such as SEM, XRD, mean pore size and porosity analysis. Four types of chemical cleaning agents were selected for chemical in place cleaning of the fouled mullite membrane: Acid (sulfuric acid (H2SO4)), surfactant (sodium dodecyl sulfate (SDS)), chelating agent (ethylene diamine tetra acetic acid (EDTA)) and alkaline (sodium hydroxide (NaOH)). The fouled membranes were cleaned with single, binary and ternary solution of these chemical agents with the concentrations of 5 mM and 10 mM under the best operating conditions. After first cleaning step, membranes cleaned with vinegar and sodium bicarbonate solution as a novel chemical cleaning agent and named as second cleaning step. Results showed that by using single component chemical agent, EDTA and SDS with concentration of 5 and 10 mM were the best cleaning agents which have flux recovery about 31.265% and 57.778% respectively after two steps of cleaning. Binary solution of SDS + EDTA with the concentration of 5 mM was the best cleaning agent among binary and ternary cleaning solution agents which led to 41.802% and 65.163% flux recovery in the first and second cleaning steps of chemical clanging process respectively.