title: Effect of increased load of high-strength food wastewater in thermophilic and mesophilic anaerobic co-digestion of waste activated sludge on bacterial community structure.
abstract: In recent years, anaerobic co-digestion (AcoD) has been widely used to improve reactor performance, especially methane production. In this study, we applied two different operating temperatures (thermophilic and mesophilic) and gradually increased the load of food wastewater (FWW) to investigate the bacterial communities during the AcoD of waste activated sludge (WAS) and FWW. As the load of FWW was increased, methane production rate (MPR; L CH4/L d) and methane content (%) in both Thermophilic AcoD (TAcoD) and Mesophilic AcoD (MAcoD) increased significantly; the highest MPR and methane content in TAcoD (1.423 L CH4/L d and 68.24%) and MAcoD (1.233 L CH4/L d and 65.21%) were observed when the FWW mixing ratio was 75%. However, MPR and methane yield in both reactors decreased markedly and methane production in TAcoD ceased completely when only FWW was fed into the reactor, resulting from acidification of the reactor caused by accumulation of organic acids. Pyrosequencing analysis revealed a decrease in bacterial diversity in TAcoD and a markedly different composition of bacterial communities between TAcoD and MAcoD with an increase in FWW load. For example, Bacterial members belonging to two genera Petrotoga (assigned to phylum Thermotogae) and Petrimonas (assigned to phylum Bacteroidetes) became dominant in TAcoD and MAcoD with an increase in FWW load, respectively. In addition, quantitative real-time PCR (qPCR) results showed higher bacterial and archaeal populations (expressed as 16S rRNA gene concentration) in TAcoD than MAcoD with an increase in FWW load and showed maximum population when the FWW mixing ratio was 75% in both reactors. Collectively, this study demonstrated the dynamics of key bacterial communities in TAcoD and MAcoD, which were highly affected by the load of FWW.
authors.affiliation: School of Environmental Science and Engineering, Gwangju Institute of Science and Technology, Buk-gu, Gwangju 500-712, Republic of Korea.
authors.forename: Hyun Min
authors.initials: HM
authors.lastname: Jang
authors.affiliation: Department of Integrated Environmental Systems, Pyeongtaek University, Seodong-daero 3825, Pyeongtaek 450-701, Republic of Korea.
authors.forename: Jeong Hyub
authors.initials: JH
authors.lastname: Ha
authors.affiliation: Biomass and Waste Energy Laboratory, Korea Institute of Energy Research, Yuseong-gu, Daejeon 305-343, Republic of Korea.
authors.forename: Mi-Sun
authors.initials: MS
authors.lastname: Kim
authors.affiliation: Department of Civil and Environmental Engineering, Hanyang University, Seoul 133-791, Republic of Korea.
authors.forename: Jong-Oh
authors.initials: JO
authors.lastname: Kim
authors.affiliation: School of Environmental Science and Engineering, Gwangju Institute of Science and Technology, Buk-gu, Gwangju 500-712, Republic of Korea. Electronic address: youngmo@gist.ac.kr.
authors.forename: Young Mo
authors.initials: YM
authors.lastname: Kim
authors.affiliation: School of Environmental Science and Engineering, Pohang University of Science and Technology, Pohang, Kyungbuk 790-784, Republic of Korea. Electronic address: jmpark@postech.ac.kr.
authors.forename: Jong Moon
authors.initials: JM
authors.lastname: Park
mesh_terms: D000693:Anaerobiosis; D019149:Bioreactors / Q000382:microbiology; D008697:Methane; D012336:RNA, Ribosomal, 16S; D012722:Sewage / Q000382:microbiology*; D062065:Wastewater
chemical_list: D008697:Methane; D012336:RNA, Ribosomal, 16S; D012722:Sewage; D062065:Wastewater
keywords: Anaerobic co-digestion (AcoD); Food wastewater (FWW); Microbial community; Thermophilic and mesophilic anaerobic digestion; Waste activated sludge (WAS)