Simultaneously enhanced treatment efficiency of simulated hypersaline azo dye wastewater and membrane antifouling by a novel static magnetic field membrane bioreactor (SMFMBR)

Operation performance and membrane fouling of a novel static magnetic field membrane bioreactor (SMFMBR) for treatment of hypersaline azo dye wastewater was investigated. The results showed that SMFMBRs possessed higher efficiency of dye decolorization, COD removal and detoxification than the control MBR without SMF. The (3#) SMFMBR equipped with 305.0 mT (the highest intensity) SMF displayed the best treatment performance among all the four reactors (named as 0#-3#, equipped with SMFs of 0 mT, 95.0 mT, 206.3 mT and 305.0 mT, respectively). Potentially effective microbes belonging to Rhodanobacter, Saccharibacteria genera incertae sedis, Defluviimonas, Cellulomonas, Cutaneotrichosporon, Candida and Pichia were enriched in three SMFMBRs, in both of suspended sludge and bio-cakes. The relative abundance of Candida and Pichia in suspended sludge of 3# SMFMBR was the highest among all the four reactors, suggesting their successful colonization and potentially persistent effect of bioaugmentation. On the other hand, SMF of higher intensity effectively mitigated membrane fouling. Less production of soluble microbial products (SMP) and extracellular polymeric substances (EPS), lower protein/polysaccharide (PN/PS) ratio in SMP and EPS, looser structure of bio-cakes on membrane surface, as well as lower relative abundance of potential fouling causing microbes (mainly bacteria) in microbial communities were determined in 3# SMFMBR than the other three groups.

Automated summary

The operation performance and membrane fouling of a novel static magnetic field membrane bioreactor (SMFMBR) were investigated for the treatment of hypersaline azo dye wastewater. The results showed that SMFMBRs achieved higher efficiency in dye decolorization, COD removal, and detoxification compared to the control MBR without SMF. Among the four reactors studied, the SMFMBR equipped with the highest intensity of 305.0 mT displayed the best treatment performance. The microbial community analysis revealed the enrichment of potentially effective microbes in the SMFMBRs, including Rhodanobacter, Saccharibacteria genera incertae sedis, Defluviimonas, Cellulomonas, Cutaneotrichosporon, Candida, and Pichia. Furthermore, the higher intensity of SMF effectively mitigated membrane fouling by reducing the production of soluble microbial products and extracellular polymeric substances, altering the structure of bio-cakes on the membrane surface, and decreasing the relative abundance of potential fouling-causing microbes.