title: An efficient and green pretreatment to stimulate short-chain fatty acids production from waste activated sludge anaerobic fermentation using free nitrous acid.
abstract: Short-chain fatty acid (SCFA) production from waste activated sludge (WAS) anaerobic fermentation is often limited by the slow hydrolysis rate and poor substrate availability, thus a long fermentation time is required. This paper reports a new pretreatment approach, i.e., using free nitrous acid (FNA) to pretreat sludge, for significantly enhanced SCFA production. Experimental results showed the highest SCFA production occurred at 1.8 mg FNA/L with time of day 6, which was 3.7-fold of the blank at fermentation time of day 12. Mechanism studies revealed that FNA pretreatment accelerated disruption of both extracellular polymeric substances and cell envelope. It was also found that FNA pretreatment benefited hydrolysis and acidification processes but inhibited the activities of methanogens, thereby promoting the yield of SCFA. In addition, the FNA pretreatment substantially stimulated the activities of key enzymes responsible for hydrolysis and acidification, which were consistent with the improvement of solubilization, hydrolysis and acidification of WAS anaerobic fermentation.
authors.affiliation: College of Environmental Science and Engineering, Hunan University, Changsha 410082, China; Key Laboratory of Environmental Biology and Pollution Control, Hunan University, Ministry of Education, Changsha 410082, China.
authors.forename: Xiaoming
authors.initials: X
authors.lastname: Li
authors.affiliation: College of Environmental Science and Engineering, Hunan University, Changsha 410082, China; Key Laboratory of Environmental Biology and Pollution Control, Hunan University, Ministry of Education, Changsha 410082, China.
authors.forename: Jianwei
authors.initials: J
authors.lastname: Zhao
authors.affiliation: College of Environmental Science and Engineering, Hunan University, Changsha 410082, China; Key Laboratory of Environmental Biology and Pollution Control, Hunan University, Ministry of Education, Changsha 410082, China; Advanced Water Management Centre, The University of Queensland, QLD 4072, Australia. Electronic address: w.dongbo@yahoo.com.
authors.forename: Dongbo
authors.initials: D
authors.lastname: Wang
authors.affiliation: College of Environmental Science and Engineering, Hunan University, Changsha 410082, China; Key Laboratory of Environmental Biology and Pollution Control, Hunan University, Ministry of Education, Changsha 410082, China.
authors.forename: Qi
authors.initials: Q
authors.lastname: Yang
authors.affiliation: College of Environmental Science and Engineering, Hunan University, Changsha 410082, China; Key Laboratory of Environmental Biology and Pollution Control, Hunan University, Ministry of Education, Changsha 410082, China.
authors.forename: Qiuxiang
authors.initials: Q
authors.lastname: Xu
authors.affiliation: College of Environmental Science and Engineering, Hunan University, Changsha 410082, China; Key Laboratory of Environmental Biology and Pollution Control, Hunan University, Ministry of Education, Changsha 410082, China.
authors.forename: Yongchao
authors.initials: Y
authors.lastname: Deng
authors.affiliation: College of Environmental Science and Engineering, Hunan University, Changsha 410082, China; Key Laboratory of Environmental Biology and Pollution Control, Hunan University, Ministry of Education, Changsha 410082, China.
authors.forename: Weiqiang
authors.initials: W
authors.lastname: Yang
authors.affiliation: College of Environmental Science and Engineering, Hunan University, Changsha 410082, China; Key Laboratory of Environmental Biology and Pollution Control, Hunan University, Ministry of Education, Changsha 410082, China.
authors.forename: Guangming
authors.initials: G
authors.lastname: Zeng
mesh_terms: D000693:Anaerobiosis; D002681:China; D058440:Denitrification; D005232:Fatty Acids, Volatile / Q000032:analysis*; D005285:Fermentation; D006868:Hydrolysis; D009608:Nitrous Acid / Q000737:chemistry*; D012722:Sewage / Q000737:chemistry*; D062065:Wastewater / Q000737:chemistry*; D018508:Water Purification / Q000379:methods*
chemical_list: D005232:Fatty Acids, Volatile; D009608:Nitrous Acid; D012722:Sewage; D062065:Wastewater
keywords: Anaerobic fermentation; Free nitrous acid pretreatment; Short-chain fatty acid; Waste activated sludge