title: Biogas recirculation for simultaneous calcium removal and biogas purification within an expanded granular sludge bed system treating leachate.
abstract: Biogas, generated from an expanded granular sludge bed (EGSB) reactor treating municipal solid waste (MSW) leachate, was recirculated for calcium removal from the leachate via a carbonation process with simultaneous biogas purification. Batch trials were performed to optimize the solution pH and imported biogas (CO2) for CaCO3 precipitation. With applicable pH of 10-11 obtained, continuous trials achieved final calcium concentrations of 181-375 mg/L (removal efficiencies≈92.8-96.5%) in the leachate and methane contents of 87.1-91.4% (purification efficiencies≈65.4-82.2%) in the biogas. Calcium-balance study indicates that 23-986 mg Ca/d was released from the bio-system under the carbonized condition where CaCO3 precipitating was moved outside the bioreactor, whereas 7918-9517 mg Ca/d was trapped into the system for the controlled one. These findings demonstrate that carbonation removal of calcium by biogas recirculation could be a promising alternative to pretreat calcium-rich MSW leachate and synergistically to improve methane content.
authors.affiliation: School of Environmental and Chemical Engineering, Shanghai University, 333 Nanchen Road, Shanghai 200444, PR China.
authors.forename: Jinghuan
authors.initials: J
authors.lastname: Luo
authors.affiliation: School of Environmental and Chemical Engineering, Shanghai University, 333 Nanchen Road, Shanghai 200444, PR China.
authors.forename: Xueqin
authors.initials: X
authors.lastname: Lu
authors.affiliation: School of Environmental and Chemical Engineering, Shanghai University, 333 Nanchen Road, Shanghai 200444, PR China. Electronic address: liujianyong@shu.edu.cn.
authors.forename: Jianyong
authors.initials: J
authors.lastname: Liu
authors.affiliation: School of Environmental and Chemical Engineering, Shanghai University, 333 Nanchen Road, Shanghai 200444, PR China.
authors.forename: Guangren
authors.initials: G
authors.lastname: Qian
authors.affiliation: School of Environmental and Chemical Engineering, Shanghai University, 333 Nanchen Road, Shanghai 200444, PR China.
authors.forename: Yongsheng
authors.initials: Y
authors.lastname: Lu
mesh_terms: D056804:Biofuels; D057919:Biological Oxygen Demand Analysis; D019149:Bioreactors; D002118:Calcium / Q000302:isolation & purification*; D006863:Hydrogen-Ion Concentration; D012722:Sewage; D062611:Solid Waste
chemical_list: D056804:Biofuels; D012722:Sewage; D062611:Solid Waste; D002118:Calcium
keywords: Biogas purification; Biogas recirculation; Calcium removal; EGSB; MSW leachate