Abstract In this study, anaerobic membrane bioreactor (AnMBR) was applied for the treatment of a model slurry of high-strength organic solid waste. Continuous monitoring of reactor performances by chemical analyses… Click to show full abstract
Abstract In this study, anaerobic membrane bioreactor (AnMBR) was applied for the treatment of a model slurry of high-strength organic solid waste. Continuous monitoring of reactor performances by chemical analyses and fine-scale tracing of the AnMBR sludge microbiome by high-throughput 16S rRNA gene sequencing were conducted during the long-term operation with increased organic loading rates (OLRs) up to 5.26 kgCOD m−3 day−1. Stable treatment was achieved at the highest OLR for over 170 days. The chemical oxygen demand removal rate of around 99%, membrane flux of 3.31 ± 0.40 L m−2 h−1, and biogas production rate of 31.1 ± 4.8 L day−1 were observed. The latter two parameters were improved after the sludge retention time (SRT) control, showing 4.76 ± 0.25 L m−2 h−1 and 34.5 ± 6.9 L day−1, respectively. The principal coordinate and taxonomic analyses of the sequence data showed that the sludge microbiome was changed drastically in response to both the OLR increase and SRT control. The species-level characterization showed that the relative abundances of aceticlastic methanogens, e.g., Methanosaeta concilii, decreased at high OLRs, whereas those of hydrogenotrophic methanogens, such as Methanolinea mesophila, as well as a syntrophic bacterium Smithella propionica, increased under the high OLRs and SRT control conditions. These results strongly suggest that the effective treatment of the high-strength organic solid waste slurry was mediated via the syntrophic methanogenesis pathway in the AnMBR.
               
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