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| Removal of heavy metals from pig manure by organic acids |
| Received:April 12, 2017 |
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| KeyWord:pig manure;heavy metal;organic acid;speciation;fertility |
| Author Name | Affiliation | E-mail | | DU Li-qiong | School of Environmental Science and Engineering, Nankai University, Tianjin 300350, China | | | LIU Dong-fang | School of Environmental Science and Engineering, Nankai University, Tianjin 300350, China | dongfangl@nankai.edu.cn | | HUANG Wen-li | School of Environmental Science and Engineering, Nankai University, Tianjin 300350, China | | | WEI Xiao-cheng | School of Environmental Science and Engineering, Nankai University, Tianjin 300350, China | | | YANG Dan | School of Environmental Science and Engineering, Nankai University, Tianjin 300350, China | |
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| Abstract: |
| The aim of this study was to investigate the effects of four organic acids, including citric acid, oxalic acid, tartaric acid, and malate, on heavy metals(Cu, Zn, and Mn) removal from pig manure by chemical extraction. The pig manure used in this experiment was obtained from a livestock farm in Tianjin. The treatment cost associated with the use of organic acids and use value of pig manure after extraction were also analyzed. The results showed that citric acid and oxalic acid had better leaching efficiency for heavy metals. Under optimum operation conditions, the removal efficiencies of Cu, Zn, and Mn reached 57.90%, 73.76%, and 79.56%, respectively, using citric acid and 62.72%, 59.39%, and 40.04%, respectively, using oxalic acid. The extracted Zn and Mn were primarily derived from carbonate and the Fe-Mn oxide and organic fractions, whereas Cu was primarily derived from organic fractions. The treatment cost of heavy metals increased as the solid-liquid ratio decreased, reaching RMB 126.07 and 384.24 yuan per ton using citric acid and oxalic acid, respectively, when the solid-liquid ratio was 1:5. The contents of organic matter, nitrogen, phosphorus and potassium in treated pig manure were about 815.80, 17.61, 5.49 and 0.36 g·kg-1 respectively. In general, citric acid and oxalic acid could remove heavy metals from pig manure effectively, and the pig manure after leaching had high nutrient content and fertility. |
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