Biogas potential and methanogenic community shift in in-situ anaerobic sewage sludge digestion with food waste leachate
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ARTICLE
Biogas potential and methanogenic community shift in in‑situ anaerobic sewage sludge digestion with food waste leachate additions Ji Su Bae1, Yeo Myung Yoon2, Seon Kyoung Shin1, Dong Jin Lee1* and Dong Cheol Seo3,4*
Abstract The objective of this study was to determine methane yields (MY) of organic wastes in biogasification facilities according to the mixing ratio of food waste/food waste leachate and sewage sludge. One biogasification facility that treated sewage sludge only was compared with three biogasification facilities treating sewage sludge and food waste. The theoretical MY was derived based on analyses of carbohydrate, fat, and protein to examine the efficiency of the biogasification facility. The average actual MY was 0.424 Sm3CH4/kg volatile solids, which corresponded to 83.7% of theoretical MY. In the case of combined anaerobic digestion (CD) mixing with food waste/food waste leachate, inhibitory factors (volatile fatty acids [VFAs], total nitrogen [TN], and organic matter contents) showed the tendency to have relatively higher values in CD facilities than in the biogasification facility treating sewage sludge only. Mean concentrations of VFAs and TN in the anaerobic digester effluent, and the organic loading rate were 406 mg/L, 3,721 mg/L, and 1.62 kg volatile solids/m3 day, respectively. The influence of anaerobic digester effluent was in charge of 10% within the influent environmental loading rate from the sewage treatment plants associated with the biogasification facilities. Analyses of the microbial community showed that a remarkable change in the structure of methanogens was directly related to different MY in each plant. In particular, Methanoculleus and Methanosaeta increased with an increasing ratio of food waste/food waste leachate to sludge, while Methanococcus and Methanosarcina decreased. In conclusion, CD showed steady operational conditions and high efficiency of MY by injecting food waste/food waste leachate into the anaerobic digester. It met the current criteria for integrated treatment of organic waste in biogasification facilities in South Korea. Keywords: Methane yield, Sewage sludge, Anaerobic digestion, Metagenome, Volatile solids Introduction Due to social aspects such as population growth, urbanization, and industrialization, the amount of organic wastes (containing sewage sludge and food waste) has *Correspondence: [email protected]; [email protected] 1 Environmental Resources Research Department, National Institute of Environmental Research, Environmental Research Complex, Incheon 22689, Republic of Korea 4 Division of Applied Life Science (BK21 Plus) & Institute of Agriculture and Life Science, Gyeongsang National University, Jinju 52828, Republic of Korea Full list of author information is available at the end of the article
been increasing annually in South Korea [1, 2]. In 2014, 10,112 ton/d of sewage sludge was generated, with an annual growth rate of 4.6% during the previous decade. Food waste was produced at a rate of 13,697.4 ton/d which accoun
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