title: Hydrolysis and volatile fatty acids accumulation of waste activated sludge enhanced by the combined use of nitrite and alkaline pH.
abstract: Volatile fatty acids (VFAs) production from anaerobic digestion of waste activated sludge (WAS) is often limited by the slow hydrolysis and/or poor substrate availability. Increased attention has been given to enhance the hydrolysis and acidification of WAS recently. This study presented an efficient and green strategy based on the combined use of nitrite pretreatment and alkaline pH to stimulate hydrolysis and VFA accumulation from WAS. Results showed that both proteins and polysaccharides increased in the presence of nitrite, indicating the enhancement of sludge solubilization and hydrolysis processes. Mechanism investigations showed that nitrite pretreatment could disintegrate the sludge particle and disperse extracellular polymeric substances (EPS). Then, anaerobic digestion tests demonstrated VFA production increased with nitrite treatment. The maximal VFA accumulation was achieved with 0.1 g N/L nitrite dosage and pH 10.0 at a sludge retention time (SRT) of 7 days, which was much higher VFA production in comparison with the blank, sole nitrite pretreatment, or sole pH 10. The potential analysis suggested that the combined nitrite pretreatment and alkaline pH is capable of enhancing WAS digestion with a great benefit for biological nutrient removal (BNR).
authors.affiliation: Jiangsu Key Laboratory of Chemical Pollution Control and Resources Reuse, School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing, 210094, Jiangsu province, China.
authors.forename: Cheng
authors.initials: C
authors.lastname: Huang
authors.affiliation: Jiangsu Key Laboratory of Chemical Pollution Control and Resources Reuse, School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing, 210094, Jiangsu province, China.
authors.forename: Congcong
authors.initials: C
authors.lastname: Liu
authors.affiliation: Jiangsu Key Laboratory of Chemical Pollution Control and Resources Reuse, School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing, 210094, Jiangsu province, China. sunxyun@njust.edu.cn.
authors.forename: Xiuyun
authors.initials: X
authors.lastname: Sun
authors.affiliation: Jiangsu Key Laboratory of Chemical Pollution Control and Resources Reuse, School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing, 210094, Jiangsu province, China.
authors.forename: Yinglu
authors.initials: Y
authors.lastname: Sun
authors.affiliation: Jiangsu Key Laboratory of Chemical Pollution Control and Resources Reuse, School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing, 210094, Jiangsu province, China.
authors.forename: Rui
authors.initials: R
authors.lastname: Li
authors.affiliation: Jiangsu Key Laboratory of Chemical Pollution Control and Resources Reuse, School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing, 210094, Jiangsu province, China.
authors.forename: Jiansheng
authors.initials: J
authors.lastname: Li
authors.affiliation: Jiangsu Key Laboratory of Chemical Pollution Control and Resources Reuse, School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing, 210094, Jiangsu province, China.
authors.forename: Jinyou
authors.initials: J
authors.lastname: Shen
authors.affiliation: Jiangsu Key Laboratory of Chemical Pollution Control and Resources Reuse, School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing, 210094, Jiangsu province, China.
authors.forename: Weiqing
authors.initials: W
authors.lastname: Han
authors.affiliation: Jiangsu Key Laboratory of Chemical Pollution Control and Resources Reuse, School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing, 210094, Jiangsu province, China.
authors.forename: Xiaodong
authors.initials: X
authors.lastname: Liu
authors.affiliation: Jiangsu Key Laboratory of Chemical Pollution Control and Resources Reuse, School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing, 210094, Jiangsu province, China. wanglj@njust.edu.cn.
authors.forename: Lianjun
authors.initials: L
authors.lastname: Wang
mesh_terms: D005232:Fatty Acids, Volatile / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D009573:Nitrites / Q000737:chemistry; D011134:Polysaccharides / Q000737:chemistry; D011506:Proteins / Q000737:chemistry; D012722:Sewage / Q000737:chemistry*
chemical_list: D005232:Fatty Acids, Volatile; D009573:Nitrites; D011134:Polysaccharides; D011506:Proteins; D012722:Sewage
keywords: Acidification; Alkaline digestion; Anaerobic digestion; Hydrolysis; Nitrite; Waste activated sludge