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Performance of a forward osmotic membrane bioreactor for anaerobic digestion of waste sludge with increasing solid concentration
- Zhao, Jing, Li, Yunqian, Pan, Shuang, Tu, Qianqian, Zhu, Hongtao
- Journal of environmental management 2019 v.246 pp. 239-246
- Actinobacteria, Bacteroidetes, Chloroflexi, Proteobacteria, anaerobic digestion, biogas, crystals, fouling, ions, magnesium, magnesium ammonium phosphate, magnesium chloride, membrane bioreactors, methane, methane production, microbial communities, organic matter, osmosis, sludge, total solids
- A forward osmotic membrane bioreactor for sludge anaerobic digestion (ad-OMBR) could realize high-solid digestion via drawing moisture out by forward osmosis (FO). Methane production and microbial community evolution were monitored in an ad-OMBR as the total solids (TS) content was gradually increased. With magnesium chloride (MgCl2) and cellulose triacetate (CTA) membrane as a draw solution and FO membrane, respectively, the ad-OMBR exhibited better performance than the conventional digester, with higher solid content, organic degradation and methane content in biogas. The conductivity of the ad-OMBR did not increase, potentially because of the formation of struvite crystals aided by the reverse-fluxed Mg2+ ions. Microbial diversity increased along with the increase in solid content based on the Shannon index, while the most operational taxonomic units were obtained in the 8% TS sludge Although phylum Firmicutes decreased when the TS content was raised to 11%, the relative abundance of Proteobacteria, Chloroflexi, Actinobacteria, and Bacteroidetes, which could also degrade organic matter, increased with increasing TS in ad-OMBR. FO membrane fouling in ad-OMBR was highly reversible.