Chemical precipitation is a widely applied approach for a liquid fraction of digestate(LFD)of agricultural waste but its large-scale application requires low-cost and efficient precipitating agents and novel process d...Chemical precipitation is a widely applied approach for a liquid fraction of digestate(LFD)of agricultural waste but its large-scale application requires low-cost and efficient precipitating agents and novel process design.This study evaluated novel approach for the efficient removal of contaminants from the LFD using fly ash-based chemical precipitation,followed by filtration and CO_(2) mineralization.The technical feasibility of this approach was evaluated using pH and electrical conductivity(EC),and removal efficiencies of total phosphorus(TP),chemical oxygen demand(COD)and heavy metals during the treatment.The fly ash used in this study showed a promising performance as a chemical precipitation agent for COD and TP removal from the treated LFD involving complex effects of precipitation and adsorption.CO_(2) bubbling after fly ash-based chemical precipitation provided further COD and TP removal by carbonation reactions between CO_(2) and the excessive alkaline minerals in fly ash.Although addition of fly ash to untreated LFD increased pH from 8.3 to 12.9 and EC from 7.01 to 13.7 mS·cm^(−1),CO_(2) bubbling helped neutralize the treated LFD and reduce the EC,and concentrations of toxic ions by carbonation reactions.The fly ash-based chemical precipitation and CO_(2) mineralization had>93%COD and>98%TP removal efficiencies,and resulted in an EC of<2 mS·cm^(−1) and a neutral pH in the treated LFD,as well as the high purity calcite product.展开更多
基金supports from the Jinhua Polytechnic(SGYC11070201X004)Jinhua City Public Welfare Application Research Project(2022-4-002)Fundamental Research Funds for the Central Universities(2662020GXD002).
文摘Chemical precipitation is a widely applied approach for a liquid fraction of digestate(LFD)of agricultural waste but its large-scale application requires low-cost and efficient precipitating agents and novel process design.This study evaluated novel approach for the efficient removal of contaminants from the LFD using fly ash-based chemical precipitation,followed by filtration and CO_(2) mineralization.The technical feasibility of this approach was evaluated using pH and electrical conductivity(EC),and removal efficiencies of total phosphorus(TP),chemical oxygen demand(COD)and heavy metals during the treatment.The fly ash used in this study showed a promising performance as a chemical precipitation agent for COD and TP removal from the treated LFD involving complex effects of precipitation and adsorption.CO_(2) bubbling after fly ash-based chemical precipitation provided further COD and TP removal by carbonation reactions between CO_(2) and the excessive alkaline minerals in fly ash.Although addition of fly ash to untreated LFD increased pH from 8.3 to 12.9 and EC from 7.01 to 13.7 mS·cm^(−1),CO_(2) bubbling helped neutralize the treated LFD and reduce the EC,and concentrations of toxic ions by carbonation reactions.The fly ash-based chemical precipitation and CO_(2) mineralization had>93%COD and>98%TP removal efficiencies,and resulted in an EC of<2 mS·cm^(−1) and a neutral pH in the treated LFD,as well as the high purity calcite product.
