메탄생성 미생물 군집변화의 다변량분석을 통한 돈분뇨 2단 혐기소화공정 해석

Abstract

Laboratory experiments were conducted to investigate two-stage anaerobic digestion of swine wastewater. In this study, the two-stage methanogenic reactor was operated by acidogenic reactor with HRT of 2 days and 50 oC and methanogenic reactor to vary hydraulic retention time (HRT) with 35 oC. In the optimized thermophilic-acidogenic stage throughout the entire experimental period, VS was reduced by 13.8% (±1.6%)

however, COD hardly decreased because of the thermophilic hydrolysis of major organic materials, such as carbohydrates, proteins, and lipids, without any significant consumption of volatile fatty acids (VFAs). In the methanogenic stage, COD was reduced by 65.8 (±1.1)% compared to a 47.4 (±2.9)% reduction in VS reduction efficiency, indicating the gradual increase in methane production and the gradual decrease in methane yield during a HRT between 25 and 10 days. This was probably due to the fact that methanogens consume a substantial amount of the VFAs produced as a result of the degradation of major organic materials by bacteria.Change of methanogen community, associated with changes in chemical profiles, was investigated and monitored by quantitative real-time PCR (QPCR) based on archaeal denaruting gel gradient electrophoresis (DGGE). Methanoculleus bourgnesis, belonging to Mehtanomicrobiales (MMB) was predominant during a HRT between 25 and 10 days, while Methanobrevibacter sp. AbM4, belonging to Methanobacteriales (MBT) was predominant during a HRT between 10 and 5 days. Overall 16S rRNA gene concentration also gradually decreased with decline of HRT. In order to understand correlation between methanogen community and environmental variables, redundancy analysis (RDA) was conducted by software CANOCO 4.5.A 20 m3 pilot-scale two-stage anaerobic reactor was operated in continuously for 70 days. The plant was seeded with mesophilic anaerobic sludge (Chemical Oxygen Demand (COD), 12.44 g/L) obtained from a full-scale treatment plant for municipal wastewater treatment. During the start-up period for 15days, the flow rate in reactor was kept increasing from HRT of 50 to 20 days. Although COD and VS residual concentration was already constant at average 54.4 (±3.8) g/L and 24.8 (±2.2)g/L, biogas production has still increased from 3.3 to 11.7 m3/m3/d.