title: Effect of Calcium Ions on Dewaterability of Enzymatic-Enhanced Anaerobic Digestion Sludge.
abstract: Waste-activated sludge (WAS) solubilized remarkably after enzymatic-enhanced anaerobic digestion, but its dewaterability was deteriorated. In this study, a novel method was performed to improve the dewaterability of enzymatic-enhanced anaerobic digestion sludge by adding CaCl2 (0.01~1.00 g/g total sludge). The capillary suction time (CST), moisture content, and filtrate turbidity were employed to characterize the dewaterability of WAS, and the possible mechanisms involved were clarified. The results showed the dewaterability did not worsen when CaCl2 was added before sludge digestion, and the CST, moisture content, and filtrate turbidity were notably reduced with the increase of CaCl2 dosage. It also shown that calcium ions played an important role in the bioflocculation of digested sludge by neutralizing negative charges on the surface of sludge. In addition, soluble protein initially lowered a little and then observably improved with the addition of CaCl2, while soluble carbohydrate was reduced sharply first and then bounced back afterwards. The interactions between calcium ions and the biopolymer further enhanced the dewatering of sludge through bridging of colloidal particles together.
authors.affiliation: Department of Biological and Environmental Engineering, Changsha University, Changsha, 410003, People's Republic of China, luokungood2006@163.com.
authors.forename: Kun
authors.initials: K
authors.lastname: Luo
authors.forename: Qi
authors.initials: Q
authors.lastname: Yang
authors.forename: Xiao-Ming
authors.initials: XM
authors.lastname: Li
authors.forename: Shi-Ying
authors.initials: SY
authors.lastname: Zhang
authors.forename: Ya
authors.initials: Y
authors.lastname: Pang
authors.forename: Xue
authors.initials: X
authors.lastname: Li
authors.forename: Xing-Sheng
authors.initials: XS
authors.lastname: Liao
mesh_terms: D000693:Anaerobiosis; D001673:Biodegradation, Environmental; D001704:Biopolymers / Q000032:analysis; D002118:Calcium / Q000737:chemistry*; D002122:Calcium Chloride / Q000737:chemistry; D002241:Carbohydrates / Q000032:analysis; D006813:Humidity; D007477:Ions; D009391:Nephelometry and Turbidimetry; D010447:Peptide Hydrolases / Q000378:metabolism*; D011506:Proteins / Q000032:analysis; D012722:Sewage / Q000737:chemistry* / Q000382:microbiology; D012995:Solubility; D012996:Solutions; D055672:Static Electricity; D013997:Time Factors; D014866:Waste Products; D014867:Water / Q000737:chemistry*; D000516:alpha-Amylases / Q000378:metabolism*
chemical_list: D001704:Biopolymers; D002241:Carbohydrates; D007477:Ions; D011506:Proteins; D012722:Sewage; D012996:Solutions; D014866:Waste Products; D014867:Water; D000516:alpha-Amylases; D010447:Peptide Hydrolases; D002122:Calcium Chloride; D002118:Calcium