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| Removing Cu and Zn from pig manure via the leaching method with EDTA, saponin, and their mixture |
| Received:March 08, 2018 |
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| KeyWord:pig manure;EDTA;saponin;heavy metal;speciation |
| Author Name | Affiliation | E-mail | | LI Zhen-dong | College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China | | | LIU Dong-fang | College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China | dongfangl@nankai.edu.cn | | HUANG Wen-li | College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China | | | WEI Xiao-cheng | College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China | | | SUN Yu | College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China | |
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| Abstract: |
| The aim of this study is to explore the feasibility of using EDTA, saponin, and their mixture as eluting agents to remove heavy metals from livestock manure. The pig manure used in the experiment was obtained from a large-scale farm. The effects of EDTA, saponin, and their mixture(E-S mixture) on the removal of Cu and Zn from pig manure under different conditions, such as various concentrations, pH levels, liquid-solid ratios, and reaction time, were studied. The binding forms of heavy metals and the agricultural value of pig manure were analyzed before and after the treatment. Results showed that Cu and Zn could be efficiently leached out from pig manure by both EDTA and the E-S mixture. Under optimum operating conditions, the leaching efficiency of Cu and Zn were 75.28% and 89.26%, respectively, with EDTA and 81.44% and 91.27%, respectively, with the E-S mixture. The extracted Cu and Zn were primarily derived from the exchangeable forms and some carbonate fractions using saponin, and all fractions of heavy metals were removed using EDTA and the E-S mixture excluding the residual fraction. The average contents of organic matter, total nitrogen, total potassium, and total phosphorus in the treated pig manure were 897.93, 20.15, 0.64, and 8.66 g·kg-1, respectively. The study indicates that chemical leaching with EDTA and the E-S mixture is highly efficient in the removal of Cu and Zn from pig manure. EDTA and the E-S mixture remove most of the heavy metals in unstable forms. In addition, the treated pig manure retain a high nutrient content and fertility and does not need to be further processed. |
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