Enzymatic cleaning in ultrafiltration of wastewater treatment plant effluent

Membrane fouling is still one of the most important issues in membrane filtration applications. Organic (macro) molecules such as polysaccharides and proteins are the main components of extracellular polymeric substances (EPS) which contribute to irreversible membrane fouling in ultrafiltration of wastewater treatment plant (WWTP) effluent. In this study, irreversible fouling by proteins as constituents of WWTP effluent was investigated by testing a new enzymatic cleaning protocol at pilot scale. Overall the tested enzymatic cleaning protocol showed a better performance in the recovery of clean water flux (CWF) than its basic alkaline cleaning protocol, which implied that proteins may play an important role in the development of irreversible fouling in this research. Application of the new enzymatic cleaning protocol at low temperatures (25-30°C) resulted in recovery of CWF of 100%. If metal complexes were formed during ultrafiltration of conditioned (pre-filtered) WWTP effluent by coagulant dosing, the application of an acid cleaning previous to the enzymatic cleaning is suggested.