Physical and chemical cleaning for nanofiltration/reverse osmosis (NF/RO) membranes in treatment of tertiary palm oil mill effluent (POME) for water reclamation

Treatment of palm oil mill effluent (POME) with membranes can cause membrane fouling due to the presence of suspended solids and organic matters. The objective of this paper is to evaluate the performance of three types of membranes (NF270, XLE, and BW30) after the physical and chemical cleaning. Continuous chemical cleaning was conducted with NaOH and with HCl to clean the fouled membrane so as to elucidate the chemical cleaning protocols and cleaning efficiency. Flushing with ultra-pure (UP) water enabled the recovery of the fluxes of XLE and BW 30 membranes, as reflected by the mild decline (~1%) in the flux recovery for the XLE and BW 30 membranes. XLE and BW 30 membranes have exhibited consistent rejection capabilities throughout the 3-cycle filtration period. Conversely, NF 270 has failed to regain its rejection capability in the long run. Whereas, for chemical cleaning, the initial flux of NF 270 after cleaning with 0.1% NaOH rose dramatically compared to the initial flux in the first filtration cycle due to changes in the surface morphology. Conversely, NaOH cleaning had fully recovered the initial flux of the XLE and BW 30 membranes without compromise the rejection capabilities of both membranes. Based on the cleaning efficiency and permeate quality, it can be concluded that the BW 30 membrane with ultra-pure water (UP) and NaOH cleanings afforded the best and most consistent performance in the long run but HCl is not a preference for the cleaning of this membrane in the water reclamation due to the low flux recovery