title: Enhanced anaerobic digestion of waste activated sludge digestion by the addition of zero valent iron.
abstract: Anaerobic digestion is promising technology to recover energy from waste activated sludge. However, the sludge digestion is limited by its low efficiency of hydrolysis-acidification. Zero valent iron (ZVI) as a reducing material is expected to enhance anaerobic process including the hydrolysis-acidification process. Considering that, ZVI was added into an anaerobic sludge digestion system to accelerate the sludge digestion in this study. The results indicated that ZVI effectively enhanced the decomposition of protein and cellulose, the two main components of the sludge. Compared to the control test without ZVI, the degradation of protein increased 21.9% and the volatile fatty acids production increased 37.3% with adding ZVI. More acetate and less propionate are found during the hydrolysis-acidification with ZVI. The activities of several key enzymes in the hydrolysis and acidification increased 0.6-1 time. ZVI made the methane production raise 43.5% and sludge reduction ratio increase 12.2 percent points. Fluorescence in situ hybridization analysis showed that the abundances of hydrogen-consuming microorganisms including homoacetogens and hydrogenotrophic methanogens with ZVI were higher than the control, which reduced the H2 accumulation to create a beneficial condition for the sludge digestion in thermodynamics.
authors.affiliation: Key Laboratory of Industrial Ecology and Environmental Engineering, Ministry of Education, School of Environmental Science and Technology, Dalian University of Technology, Dalian 116024, China.
authors.forename: Yinghong
authors.initials: Y
authors.lastname: Feng
authors.affiliation: Key Laboratory of Industrial Ecology and Environmental Engineering, Ministry of Education, School of Environmental Science and Technology, Dalian University of Technology, Dalian 116024, China. Electronic address: zhangyb@dlut.edu.cn.
authors.forename: Yaobin
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Industrial Ecology and Environmental Engineering, Ministry of Education, School of Environmental Science and Technology, Dalian University of Technology, Dalian 116024, China.
authors.forename: Xie
authors.initials: X
authors.lastname: Quan
authors.affiliation: Key Laboratory of Industrial Ecology and Environmental Engineering, Ministry of Education, School of Environmental Science and Technology, Dalian University of Technology, Dalian 116024, China.
authors.forename: Suo
authors.initials: S
authors.lastname: Chen
mesh_terms: D000693:Anaerobiosis; D056804:Biofuels; D004798:Enzymes / Q000378:metabolism; D005227:Fatty Acids / Q000378:metabolism; D006859:Hydrogen / Q000378:metabolism; D006868:Hydrolysis; D017404:In Situ Hybridization, Fluorescence; D007501:Iron; D008697:Methane / Q000378:metabolism; D059013:Microbial Consortia; D011134:Polysaccharides / Q000378:metabolism; D011506:Proteins / Q000378:metabolism; D012722:Sewage / Q000382:microbiology; D014865:Waste Disposal, Fluid / Q000379:methods*
chemical_list: D056804:Biofuels; D004798:Enzymes; D005227:Fatty Acids; D011134:Polysaccharides; D011506:Proteins; D012722:Sewage; D006859:Hydrogen; D007501:Iron; D008697:Methane
keywords: Anaerobic digestion; Methane production; Sludge reduction; Waste activated sludge; Zero-valent iron