Heavy metals removal from municipal solid waste incineration fly ashes by electric field enhanced washing with citric acid/ammonium citrate
DENY Yi1,2,, LI Shuyuan1, WANG Jiqin2, TIAN Yang2, YI Xiaoxia2, WANG Rong2,3, YANG Feihua4, WANG Zhaojia4, SHU Jiancheng2, SUN Zhi5, CHEN Mengjun2,, 1.Solid Waste and Chemical Management Technology Center of the Ministry of Ecological Environment, Beijing 100000, China 2.Key Laboratory of Solid Waste Treatment and Resource Recycle, Ministry of Education, Southwest University of Science and Technology, Mianyang 621010, China 3.School of National Defense Science and Technology, Southwest University of Science and Technology, Mianyang 621010, China 4.State Key Laboratory of Solid Waste Reuse for Building Materials, Beijing 100041, China 5.Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China
Abstract:Citric acid and ammonium citrate were applied to further enhance the removal of heavy metals from municipal solid waste incineration fly ashes by electric washing. The effects of initial pH, auxiliary agent concentration and current density on the removal rate of heavy metals from fly ash were studied, and the leaching risk of treated fly ash was discussed. These results indicate that both citric acid and ammonium citrate aided electric enhanced washing could significantly remove heavy metals from fly ashes, and the removal rate increases with the decrease of initial pH and the increase of auxiliary agent concentration and current density. At optimum conditions, with the addition of citric acid auxiliary agent, the removal rates of Pb, Cd and Ni in the fly ash are all higher than 90%, while the removal rates of Zn, Cu and As are 83.12%, 72.68% and 71.86% respectively. When ammonium citrate is used as an auxiliary agent, the removal rates of Cd, Cu, Ni, Zn, As and Pb removal rates are 91.51%, 88.18%, 86.43%, 77.94%, 69.57% and 69.07%, respectively. The fly ash treated with the two auxiliary agents has no leaching toxicity since their leaching concentrations either could not be detected or at an extremely lower level. The results provide references for electric field washing removal and enhancement of heavy metals in fly ash. Key words:municipal solid waste/ incineration fly ashes/ heavy metals/ electric field enhanced washing.
图1电场强化脱除实验装置示意图 Figure1.Experimental apparatus of electric field enhanced washing system
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1.Solid Waste and Chemical Management Technology Center of the Ministry of Ecological Environment, Beijing 100000, China 2.Key Laboratory of Solid Waste Treatment and Resource Recycle, Ministry of Education, Southwest University of Science and Technology, Mianyang 621010, China 3.School of National Defense Science and Technology, Southwest University of Science and Technology, Mianyang 621010, China 4.State Key Laboratory of Solid Waste Reuse for Building Materials, Beijing 100041, China 5.Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China Received Date: 2020-09-09 Accepted Date: 2021-01-21 Available Online: 2021-04-23 Keywords:municipal solid waste/ incineration fly ashes/ heavy metals/ electric field enhanced washing Abstract:Citric acid and ammonium citrate were applied to further enhance the removal of heavy metals from municipal solid waste incineration fly ashes by electric washing. The effects of initial pH, auxiliary agent concentration and current density on the removal rate of heavy metals from fly ash were studied, and the leaching risk of treated fly ash was discussed. These results indicate that both citric acid and ammonium citrate aided electric enhanced washing could significantly remove heavy metals from fly ashes, and the removal rate increases with the decrease of initial pH and the increase of auxiliary agent concentration and current density. At optimum conditions, with the addition of citric acid auxiliary agent, the removal rates of Pb, Cd and Ni in the fly ash are all higher than 90%, while the removal rates of Zn, Cu and As are 83.12%, 72.68% and 71.86% respectively. When ammonium citrate is used as an auxiliary agent, the removal rates of Cd, Cu, Ni, Zn, As and Pb removal rates are 91.51%, 88.18%, 86.43%, 77.94%, 69.57% and 69.07%, respectively. The fly ash treated with the two auxiliary agents has no leaching toxicity since their leaching concentrations either could not be detected or at an extremely lower level. The results provide references for electric field washing removal and enhancement of heavy metals in fly ash.
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