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Anaerobic digestion of chemically enhanced primary treatment (CEPT) sludge and the microbial community structure


The effectiveness and treatment conditions of FeCl3- and AlCl3-coagulated municipal sewage sludge from chemically enhanced primary treatment (CEPT) using anaerobic digestion (AD) and the structure of microbial community were investigated. The results based on 297 measurements under different operational conditions demonstrate good average AD performance of CEPT sludge, that is, percent volatile solid reduction of 58 %, specific biogas production (or biogas yield) of 0.92 m3/kg volatile solids (VS) destroyed, and methane content of 65.4 %. FeCl3 dosing, organic loading rate, temperature, and hydraulic retention time all significantly affected AD performance. FeCl3 dosing greatly improved specific methane production (methane yield) by 38–54 % and significantly reduced hydrogen sulfide (H2S) content in biogas (from up to 13,250 to <200 ppm), contributing to higher methane recovery and simplified biogas cleaning for power generation. Metagenomic analysis suggested that anaerobic digesters of both CEPT sludge and combined primary and secondary sludge were dominated by Bacteroidetes, Proteobacteria, Firmicutes, Actinobacteria, Thermotogae, and Chloroflexi. However, Methanomicrobia methanogens were better enriched in the anaerobic digesters of CEPT sludge than in the combined sludge. Further, different sources of CEPT sludge with various chemical properties nurtured shared and unique microbial community composition. Combined, this study supports AD as an efficient technology for CEPT sludge treatment and poses first insights into the microbial community structure.

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The authors thank Collaborative Research Fund (CRF, C7044-14G) for financial support. Feng Ju and Yubo Wang would like to thank the University of Hong Kong (HKU) for the postgraduate scholarship.

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Correspondence to Tong Zhang.

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This article does not contain any studies with human participants or animals performed by any of the authors. The authors declare that they have no conflict of interest.

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Ju, F., Wang, Y., Lau, F.T.K. et al. Anaerobic digestion of chemically enhanced primary treatment (CEPT) sludge and the microbial community structure. Appl Microbiol Biotechnol 100, 8975–8982 (2016).

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  • Anaerobic digestion
  • CEPT
  • Biogas production
  • Solid reduction
  • Microbial community
  • Metagenomics