Chemical cleaning of utafiltration membrane after treatment of oily wastewater

Oily wastewaters in Tehran refinery has become a big issue of water and environment pollution to be solved urgently. Ultrafiltration (UF) membranes play an important role in the treatment and reuse of oily wastewaters. Fouling of UF membranes is typically caused by inorganic and organic materials present in wastewaters that adhere to the surface and pores of the membrane and results in deterioration of performance (reduce membrane flux) with a consequent increase in costs of energy and membrane replacement. In the experiments, polyacrylonitrile and outlet wastewater of the API unit of Tehran refinery as membrane and feed were used, respectively. Fouling and cleaning experiments wereperformed with oily wastewater and selected cleaning agents using a laboratory scale cross flow test unit. The results showed that metal chelating agent (EDTA) and an anionic surfactant (SDS) were able to clean the fouled UF membrane effectively by optimizing chemical (pH) and physical (cleaning time, cross flow velocity (CFV) and temperature) conditions during cleaning. Flux recovery and resistance removal found to were improve with increasing CFV, temperature, pH, cleaning time and concentration of the cleaning chemicals. In this paper, the cleaning mechanism is also investigated.

Keywords:

Oily wastewater , Cleaning , UF , Fouling