Evaluation of pH regulation in carbohydrate-type municipal waste anaerobic co-fermentation: Roles of pH at acidic, neutral and alkaline conditions

• DOI: 10.1016/j.scitotenv.2022.158327
• Publication Date: 2022-08-28T04:50:46Z
• Authors: Chuan Shi; Jinyuan Ma; Houkai Wu; Juan Luo; Yue Liu; Kun Li; Yuexi Zhou; Kaijun Wang
• Keywords: Sewage; Ethanol; Extracellular Polymeric Substance Matrix; Carbohydrates; Carbon Dioxide; Hydrogen-Ion Concentration; Fatty Acids, Volatile; 6. Clean water; 12. Responsible consumption; Bioreactors; Ammonia; Fermentation; 11. Sustainability; Anaerobiosis; Lactic Acid; Acids

This study investigated and evaluated the roles of acidic (pH 4.0), neutral (pH 7.0) and alkaline (pH 10.0) in anaerobic co-fermentation of sewage sludge and carbohydrate-type municipal waste. CO2, CH4 and H2 are produced in acidic, neutral and alkaline fermentation, respectively. The neutral co-fermentation contained the vast number of aqueous metabolites as total of 22.12 g/L, with the advantage of over 50 % biodegradable components in extracellular polymeric substance and over 80 % hydrolysis rate. Acidic and alkaline pH facilitated ammonia release, with the max concentration of 0.46 g/L and 0.44 g/L, respectively. Microbial analysis indicated that pH is the key parameter to impact microbial activity and drive microbial community transition. The high abundance of Lactobacillus, Bifidobacterium and Clostridium was associated with harvest of ethanol, lactic acid and acetate in acidic, neutral and alkaline fermentation. Meanwhile, the floc feature showed better dewaterability (zeta potential -8.48 mV) and poor nutrient convey (distribution spread index 1.03) in acidic fermentation. In summary, acidic and alkaline fermentation were prioritised for targeted spectrum. Neutral fermentation was prioritised for high production. This study presented an upgraded understanding of the pH role in fermentation performance, microbial structure and sludge behaviour, which benefits the development of fermentation processing unit.