EFFECTS OF GASEOUS H2 AND CO2 REMOVAL ON THERMOPHILIC ANAEROBIC DIGESTION
The effects of gaseous H2 and CO2 removal on thermophlic anaerobic digestion were studied by investigating their roles in changing physicochemical characteristics of the niche, reaction rates, metabolic pathways and microorganisms. Three thermophilic anaerobic sequenced bioreactors (ASBR) i.e. R0 without gas removal, R1 with H2 depleted and R2 with H2/CO2 removed were set up. In R1, partial pressure of H2 was decreased from 10-2 atm to 10-4 atm through a dehydrogenation column. In R2, by N2 sparging, partial pressure of H2 (pH2) and CO2 (pCO2) dropped from 10-2 atm to 10-3 atm and 0.35±0.05 atm to 0.03±0.02 atm, respectively. The results demonstrated that removal of gaseous H2 and CO2 could enhance the stability of thermophilic anaerobic digestion. H2 removal accelerated glucose degradation thermodynamically. Under low pH2, butyrate-type fermentation dominated while hydrogenotrophic methanogenesis declined. The loss of H2 impaired CO2 reduction, thus reduced CH4 yield while increased CO2 generation. Accompanied by H2 removal, CO2 removal in the stable state apparently increased pH to an extent that it exceeded the optimum pH range for methanogens under low organic loading rate. Therefore, it delayed methanogenesis and didnt improve the performance of the ASBR. Gas sparging promoted the mixing, facilitated the entrapped H2 and CO2 release to the gas and increased CO2 production. SEM analysis indicated that H2 and CO2 removal reduced the microbial diversity and caused a shift of the dominant anaerobes in the glucose-fed ASBRs.
hydrogen partial pressure carbon dioxide partial pressure N2 sparging thermophilic anaerobic digestion
L.P. HAO P.J. HE F. L(U) L.M. SHAO
Institute of Waste Treatment and Reclamation, College of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai 200092, China
国际会议
北京
英文
1143-1148
2010-05-17（万方平台首次上网日期，不代表论文的发表时间）