title: Inhibiting excessive acidification using zero-valent iron in anaerobic digestion of food waste at high organic load rates.
abstract: Excessive acidification occurs frequently in food waste (FW) anaerobic digestion (AD) due to the high carbon-to-nitrogen ratio of FW. In this study, zero-valent iron (ZVI) was applied to prevent the excessive acidification. All of the control groups, without ZVI addition (pH∼5.3), produced little methane (CH4) and had high volatile fatty acids/bicarbonate alkalinity (VFA/ALK). By contrast, at OLR of 42.32gVS/Lreactor, the pH of effluent from the reactors with 0.4g/gVSFWadded of ZVI increased to 7.8-8.2, VFA/ALK decreased to <0.1, and the final CH4 yield was ∼380mL/gVSFWadded, suggesting inhibition of excessive acidification. After adding powdered or scrap metal ZVI to the acidogenic reactors, the fractional content of butyric acid changed from 30-40% to 0%, while, that of acetic acid increased. These results indicate that adding ZVI to FW digestion at high OLRs could eliminate excessive acidification by promoting butyric acid conversion and enhancing methanogen activity.
authors.affiliation: Key Laboratory for Solid Waste Management and Environment Safety, Ministry of Education of China, School of Environment, Tsinghua University, Beijing 10084, China.
authors.forename: Xin
authors.initials: X
authors.lastname: Kong
authors.affiliation: Key Laboratory for Solid Waste Management and Environment Safety, Ministry of Education of China, School of Environment, Tsinghua University, Beijing 10084, China.
authors.forename: Yonghong
authors.initials: Y
authors.lastname: Wei
authors.affiliation: Key Laboratory for Solid Waste Management and Environment Safety, Ministry of Education of China, School of Environment, Tsinghua University, Beijing 10084, China.
authors.forename: Shuang
authors.initials: S
authors.lastname: Xu
authors.affiliation: Key Laboratory for Solid Waste Management and Environment Safety, Ministry of Education of China, School of Environment, Tsinghua University, Beijing 10084, China. Electronic address: jgliu@tsinghua.edu.cn.
authors.forename: Jianguo
authors.initials: J
authors.lastname: Liu
authors.affiliation: Shenzhen Environmental Microbial Application and Risk Control Key Laboratory, Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055, China.
authors.forename: Huan
authors.initials: H
authors.lastname: Li
authors.affiliation: Key Laboratory for Solid Waste Management and Environment Safety, Ministry of Education of China, School of Environment, Tsinghua University, Beijing 10084, China.
authors.forename: Yili
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Key Laboratory for Solid Waste Management and Environment Safety, Ministry of Education of China, School of Environment, Tsinghua University, Beijing 10084, China.
authors.forename: Shuyao
authors.initials: S
authors.lastname: Yu
mesh_terms: D019342:Acetic Acid / Q000032:analysis / Q000737:chemistry / Q000378:metabolism; D000693:Anaerobiosis; D001639:Bicarbonates / Q000032:analysis / Q000737:chemistry / Q000378:metabolism; D019149:Bioreactors; D020148:Butyric Acid / Q000032:analysis / Q000737:chemistry / Q000378:metabolism; D002244:Carbon / Q000032:analysis / Q000378:metabolism; D005232:Fatty Acids, Volatile / Q000032:analysis / Q000737:chemistry / Q000378:metabolism; D005502:Food; D006863:Hydrogen-Ion Concentration; D007501:Iron / Q000737:chemistry*; D008697:Methane / Q000032:analysis / Q000737:chemistry / Q000378:metabolism; D018505:Waste Management / Q000379:methods*
chemical_list: D001639:Bicarbonates; D005232:Fatty Acids, Volatile; D020148:Butyric Acid; D002244:Carbon; D007501:Iron; D008697:Methane; D019342:Acetic Acid
keywords: Anaerobic digestion; Excessive acidification; Food waste; Inhibition; Zero-valent iron