title: Anaerobic digestion of chemically enhanced primary treatment (CEPT) sludge and the microbial community structure.
abstract: 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 m(3)/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.
authors.affiliation: Environmental Biotechnology Lab, Department of Civil Engineering, The University of Hong Kong, Hong Kong, China.
authors.forename: Feng
authors.initials: F
authors.lastname: Ju
authors.affiliation: Environmental Biotechnology Lab, Department of Civil Engineering, The University of Hong Kong, Hong Kong, China.
authors.forename: Yubo
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Drainage Services Department, The Government of the Hong Kong Special Administrative Region, Hong Kong, China.
authors.forename: Frankie T K
authors.initials: FT
authors.lastname: Lau
authors.affiliation: Drainage Services Department, The Government of the Hong Kong Special Administrative Region, Hong Kong, China.
authors.forename: W C
authors.initials: WC
authors.lastname: Fung
authors.affiliation: Environmental Biotechnology Lab, Department of Civil Engineering, The University of Hong Kong, Hong Kong, China.
authors.forename: Danping
authors.initials: D
authors.lastname: Huang
authors.affiliation: Environmental Biotechnology Lab, Department of Civil Engineering, The University of Hong Kong, Hong Kong, China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Xia
authors.affiliation: Environmental Biotechnology Lab, Department of Civil Engineering, The University of Hong Kong, Hong Kong, China. zhangt@hku.hk.
authors.forename: Tong
authors.initials: T
authors.lastname: Zhang
mesh_terms: D000077410:Aluminum Chloride; D017607:Aluminum Compounds / Q000378:metabolism; D000693:Anaerobiosis; D001419:Bacteria / Q000145:classification* / Q000378:metabolism*; D056804:Biofuels; D058448:Biota; D011232:Chemical Precipitation; D002712:Chlorides / Q000378:metabolism; D005290:Ferric Compounds / Q000378:metabolism; D056186:Metagenomics; D012722:Sewage / Q000382:microbiology*
chemical_list: D017607:Aluminum Compounds; D056804:Biofuels; D002712:Chlorides; D005290:Ferric Compounds; D012722:Sewage; D000077410:Aluminum Chloride; C024555:ferric chloride
keywords: Anaerobic digestion; Biogas production; CEPT; Metagenomics; Microbial community; Solid reduction