title: Change of pH during excess sludge fermentation under alkaline, acidic and neutral conditions.
abstract: The change in pH during excess sludge (ES) fermentation of varying sludge concentrations was investigated in a series of reactors at alkaline, acidic, and neutral pHs. The results showed that the changes were significantly affected by fermentative conditions. Under different conditions, pH exhibited changing profiles. When ES was fermented under alkaline conditions, pH decreased in a range of (10±1). At the beginning of alkaline fermentation, pH dropped significantly, at intervals of 4h, 4h, and 5h with sludge concentrations of 8665.6mg/L, 6498.8mg/L, and 4332.5mg/L, then it would become moderate. However, under acidic conditions, pH increased from 4 to 5. Finally, under neutral conditions pH exhibited a decrease then an increase throughout entire fermentation process. Further study showed short-chain fatty acids (SCFAs), ammonia nitrogen and cations contributed to pH change under various fermentation conditions. This study presents a novel strategy based on pH change to predict whether SCFAs reach their stable stage.
authors.affiliation: Key Laboratory of Beijing for Water Quality Science and Water Environment Recovery Engineering, Engineering Research Center of Beijing, Beijing University of Technology, Beijing 100124, PR China.
authors.forename: Yue
authors.initials: Y
authors.lastname: Yuan
authors.affiliation: Key Laboratory of Beijing for Water Quality Science and Water Environment Recovery Engineering, Engineering Research Center of Beijing, Beijing University of Technology, Beijing 100124, PR China. Electronic address: pyz@bjut.edu.cn.
authors.forename: Yongzhen
authors.initials: Y
authors.lastname: Peng
authors.affiliation: Key Laboratory of Beijing for Water Quality Science and Water Environment Recovery Engineering, Engineering Research Center of Beijing, Beijing University of Technology, Beijing 100124, PR China.
authors.forename: Ye
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Key Laboratory of Beijing for Water Quality Science and Water Environment Recovery Engineering, Engineering Research Center of Beijing, Beijing University of Technology, Beijing 100124, PR China.
authors.forename: Baodan
authors.initials: B
authors.lastname: Jin
authors.affiliation: Key Laboratory of Beijing for Water Quality Science and Water Environment Recovery Engineering, Engineering Research Center of Beijing, Beijing University of Technology, Beijing 100124, PR China.
authors.forename: Bo
authors.initials: B
authors.lastname: Wang
authors.affiliation: Key Laboratory of Beijing for Water Quality Science and Water Environment Recovery Engineering, Engineering Research Center of Beijing, Beijing University of Technology, Beijing 100124, PR China.
authors.forename: Shuying
authors.initials: S
authors.lastname: Wang
mesh_terms: D000143:Acids / Q000737:chemistry*; D000468:Alkalies / Q000737:chemistry*; D000641:Ammonia / Q000032:analysis; D002118:Calcium / Q000032:analysis; D005227:Fatty Acids / Q000032:analysis; D005285:Fermentation; D006863:Hydrogen-Ion Concentration; D008274:Magnesium / Q000032:analysis; D009584:Nitrogen / Q000032:analysis; D012722:Sewage / Q000737:chemistry*
chemical_list: D000143:Acids; D000468:Alkalies; D005227:Fatty Acids; D012722:Sewage; D000641:Ammonia; D008274:Magnesium; D009584:Nitrogen; D002118:Calcium
keywords: Acidic fermentation; Alkaline fermentation; Excess sludge fermentation; Neutral fermentation; pH change