title: Influence of calcium compounds as a compression framework on activated sludge dewaterability and calorific value.
abstract: Calcium compounds have been known to be important for enhancing aggregation and dewaterability of activated sludge. In this study, the effect of calcium compounds (CaO, Ca(OH)2, CaCl2, CaSO4and CaCO3, respectively) on sludge dewaterability and calorific value was investigated. Upon addition of CaO, Ca(OH)2, CaCl2, CaSO4and CaCO3(112 mg/g dry sludge) into activated sludge, after compressed filtration the moisture content of sludge was found to be 49.7%, 55.7%, 57.1%, 65.3% and 56.5%, respectively. The addition of calcium compounds altered the structure of sludge by CaCO3and Ca(OH)2production, which improved sludge filterability and provided frameworks and water passages during compression. Furthermore, sludge conditioned by CaO addition had better dewaterability than other calcium compounds. The heat generated from the CaO hydration and high pH might damage flocs' structure and improve dewaterability of sludge. Moreover, it was found that excess addition of calcium compounds led to low calorific value in combustion process. The study concluded that CaO is the optimal additive for sludge further dewatering by compressed filtration.
authors.affiliation: a Dalian National Laboratory for Clean Energy , Dalian Institute of Chemical Physics, Chinese Academy of Sciences , Dalian , People's Republic of China.|b School of Environmental Sciences and Engineering , Nanjing Tech University , Nanjing , People's Republic of China.
authors.forename: Yang
authors.identifier: http://orcid.org/0000-0001-5922-1164
authors.initials: Y
authors.lastname: Yu
authors.affiliation: a Dalian National Laboratory for Clean Energy , Dalian Institute of Chemical Physics, Chinese Academy of Sciences , Dalian , People's Republic of China.
authors.forename: Huangzhao
authors.initials: H
authors.lastname: Wei
authors.affiliation: a Dalian National Laboratory for Clean Energy , Dalian Institute of Chemical Physics, Chinese Academy of Sciences , Dalian , People's Republic of China.
authors.forename: Yonghui
authors.initials: Y
authors.lastname: Yu
authors.affiliation: a Dalian National Laboratory for Clean Energy , Dalian Institute of Chemical Physics, Chinese Academy of Sciences , Dalian , People's Republic of China.
authors.forename: Li
authors.initials: L
authors.lastname: Yu
authors.affiliation: a Dalian National Laboratory for Clean Energy , Dalian Institute of Chemical Physics, Chinese Academy of Sciences , Dalian , People's Republic of China.
authors.forename: Sen
authors.initials: S
authors.lastname: Wang
authors.affiliation: a Dalian National Laboratory for Clean Energy , Dalian Institute of Chemical Physics, Chinese Academy of Sciences , Dalian , People's Republic of China.
authors.forename: Chenglin
authors.initials: C
authors.lastname: Sun
mesh_terms: D017610:Calcium Compounds / Q000737:chemistry*; D005374:Filtration; D012722:Sewage; D014865:Waste Disposal, Fluid; D014867:Water
chemical_list: D017610:Calcium Compounds; D012722:Sewage; D014867:Water
keywords: Activated sludge; calorific value; combustion gas; compressed filtration; dewaterability