title: Enhanced volatile fatty acid production from excess sludge by combined free nitrous acid and rhamnolipid treatment.
abstract: VFA production from excess sludge (ES) was greatly enhanced by a low-cost and high-efficient treatment: 0.67mg/L free nitrous acid (FNA) pretreatment combined with 0.04g/g TSS rhamnolipid (RL) addition (FNA+RL), which significantly shortened fermentation time to 3days and increased VFA production to 352.26mgCOD/g VSS (5.42 times higher than raw ES). Propionic and acetic acids were the two leading components (71.86% of the total VFA). Mechanism investigation manifested FNA+RL improved the biodegradability of ES, achieved positive synergetic effect on solubilization, hydrolysis and acidification efficiencies, and inhibited methanation. Microbial community distribution further explained the above phenomena. The bacteria related to polysaccharides/protein utilization and VFA generation, including Clostridium, Megasphaera and Proteiniborus, were mainly observed in FNA+RL, whereas gas-forming bacteria Anaerolineae and acid-consuming bacteria Proteobacteria were assuredly suppressed. Besides, Propionibacterineae associated with propionic acid generation was exclusively enriched in sole RL and FNA+RL.
authors.affiliation: State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin 150090, PR China.
authors.forename: Qing-Lian
authors.initials: QL
authors.lastname: Wu
authors.affiliation: State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin 150090, PR China. Electronic address: guowanqian@hit.edu.cn.
authors.forename: Wan-Qian
authors.initials: WQ
authors.lastname: Guo
authors.affiliation: State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin 150090, PR China.
authors.forename: Xian
authors.initials: X
authors.lastname: Bao
authors.affiliation: State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin 150090, PR China.
authors.forename: He-Shan
authors.initials: HS
authors.lastname: Zheng
authors.affiliation: State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin 150090, PR China.
authors.forename: Ren-Li
authors.initials: RL
authors.lastname: Yin
authors.affiliation: State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin 150090, PR China.
authors.forename: Xiao-Chi
authors.initials: XC
authors.lastname: Feng
authors.affiliation: State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin 150090, PR China.
authors.forename: Hai-Chao
authors.initials: HC
authors.lastname: Luo
authors.affiliation: State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin 150090, PR China.
authors.forename: Nan-Qi
authors.initials: NQ
authors.lastname: Ren
mesh_terms: D001419:Bacteria / Q000378:metabolism; D001673:Biodegradation, Environmental; D057919:Biological Oxygen Demand Analysis; D001709:Biotechnology / Q000191:economics / Q000379:methods; D005232:Fatty Acids, Volatile / Q000096:biosynthesis*; D005285:Fermentation; D006017:Glycolipids / Q000737:chemistry*; D006868:Hydrolysis; D059013:Microbial Consortia / Q000502:physiology*; D009608:Nitrous Acid / Q000737:chemistry*; D011422:Propionates / Q000378:metabolism; D011506:Proteins / Q000378:metabolism; D012722:Sewage / Q000382:microbiology; D012995:Solubility; D014865:Waste Disposal, Fluid / Q000379:methods
chemical_list: D005232:Fatty Acids, Volatile; D006017:Glycolipids; D011422:Propionates; D011506:Proteins; D012722:Sewage; C418382:rhamnolipid; C029658:propionic acid; D009608:Nitrous Acid
keywords: Excess sludge; Free nitrous acid; Pretreatment; Rhamnolipid; Volatile fatty acid