Fouling characteristics and cleaning strategies of NF membranes for the advanced treatment of antibiotic production wastewater.

The nanofiltration (NF) membrane fouling characteristics and cleaning strategies were investigated through a laboratory-scale NF fouling test treating membrane bioreactor (MBR) effluent and MBR-granular activated carbon (GAC) effluent of an antibiotic production wastewater by DK and NF90 membranes, respectively. Results showed that organic fouling is the main NF membrane fouling for treating both the MBR effluent and MBR-GAC effluent. Soluble microbial by-product (SMP)-like and aromatic protein-like substances were the dominant components in the foulants, whereas humic-like substances had little contribution to the NF fouling. The fouling of DK was more severe than that of NF90. However, foulants respond by UV were more easily to foul NF90 membrane. It could get satisfactory effect using combined cleaning of acid (HCl, pH 2.0∼2.5) and alkali (NaOH + 0.3 wt% NaDS, pH 10.0∼10.5). The favorable cleaning strategy is "acid + alkali" for treating MBR-GAC effluent, while it is "alkali + acid" for treating MBR effluent.