title: Effect of acetic acid in recycling water on ethanol production for cassava in an integrated ethanol-methane fermentation process.
abstract: Recently, the integrated ethanol-methane fermentation process has been studied to prevent wastewater pollution. However, when the anaerobic digestion reaction runs poorly, acetic acid will accumulate in the recycling water. In this paper, we studied the effect of low concentration of acetic acid (≤25 mM) on ethanol fermentation at different initial pH values (4.2, 5.2 or 6.2). At an initial pH of 4.2, ethanol yields increased by 3.0% and glycerol yields decreased by 33.6% as the acetic acid concentration was increased from 0 to 25 mM. Raising the concentration of acetic acid to 25 mM increased the buffering capacity of the medium without obvious effects on biomass production in the cassava medium. Acetic acid was metabolized by Saccharomyces cerevisiae for the reason that the final concentration of acetic acid was 38.17% lower than initial concentration at pH 5.2 when 25 mM acetic acid was added. These results confirmed that a low concentration of acetic acid in the process stimulated ethanol fermentation. Thus, reducing the acetic acid concentration to a controlled low level is more advantageous than completely removing it.
authors.affiliation: Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, China E-mail: maozg@jiangnan.edu.cn; School of Biological Science and Technology, University of Jinan, Jinan 250022, China.
authors.forename: Xinchao
authors.initials: X
authors.lastname: Yang
authors.affiliation: Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, China E-mail: maozg@jiangnan.edu.cn.
authors.forename: Ke
authors.initials: K
authors.lastname: Wang
authors.affiliation: Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, China E-mail: maozg@jiangnan.edu.cn.
authors.forename: Jianhua
authors.initials: J
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, China E-mail: maozg@jiangnan.edu.cn.
authors.forename: Lei
authors.initials: L
authors.lastname: Tang
authors.affiliation: Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, China E-mail: maozg@jiangnan.edu.cn.
authors.forename: Zhonggui
authors.initials: Z
authors.lastname: Mao
mesh_terms: D019342:Acetic Acid / Q000737:chemistry / Q000378:metabolism*; D018533:Biomass; D000431:Ethanol / Q000378:metabolism*; D005285:Fermentation; D005990:Glycerol / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D002365:Manihot / Q000378:metabolism*; D008697:Methane / Q000378:metabolism*; D059027:Recycling; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D062065:Wastewater; D014874:Water Pollutants, Chemical / Q000378:metabolism*
chemical_list: D019342:Acetic Acid; D000431:Ethanol; D005990:Glycerol; D008697:Methane; D062065:Wastewater; D014874:Water Pollutants, Chemical