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| Removal of copper and zinc from swine manure using low-molecular-weight organic acids |
| Received:April 25, 2017 |
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| KeyWord:low-molecular-weight organic acid;swine manure;heavy metal;removal rate |
| Author Name | Affiliation | E-mail | | SHU Mei-hui | College of Environmental Sciences, Sichuan Agricultural University, Chengdu 611130, China | | | ZHANG Shi-rong | College of Environmental Sciences, Sichuan Agricultural University, Chengdu 611130, China | rsz01@163.com | | WANG Gui-yin | College of Environmental Sciences, Sichuan Agricultural University, Chengdu 611130, China | | | ZHONG Qin-mei | College of Environmental Sciences, Sichuan Agricultural University, Chengdu 611130, China | | | XU Xiao-xun | College of Environmental Sciences, Sichuan Agricultural University, Chengdu 611130, China | | | LI Ting | College of Resources, Sichuan Agricultural University, Chengdu 611130, China | |
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| Abstract: |
| It is necessary to remove heavy metals from swine manure before it can be safely used to fertilize farmland. This study was conducted to investigate the effects of concentration, contact time, pH, and the solid-liquid ratio of citric, tartaric, oxalic, and malic acids on the efficiency of the removal of Cu and Zn from swine manure by chemical leaching. The results indicated that the Cu and Zn removal efficiencies increased linearly when the concentration of the organic acids was increased. When the concentration reached 0.20 mol·L-1, oxalic acid was effective at extracting Cu(42.37%) and Zn(47.63%), whereas the efficiency of citric acid was different with regard to Cu(27.19%) and Zn(77.17%). Moreover, the kinetics tests demonstrated that the Cu and Zn removal efficiencies increased reciprocally with prolongation of contact time, and reached a relative balance at a contact time of 240 min. Furthermore, the extraction of heavy metals by organic acids was more effective under acidic conditions and decreased with increasing pH; The removal efficiencies of Cu and Zn were 41.89% and 68.14% at pH 2.00, respectively. The metal removal efficiency at a solid-liquid ratio of 1:10 was relatively high. After extraction with organic acids, the swine manure turned acidic, and its TP and TK content decreased to 8.97~10.87 g·kg-1 and 4.97~6.23 g·kg-1, respectively. Nevertheless, there was no remarkable change in TN content, and there was a slight rise in the organic matter content. Therefore, our study suggests that low-molecular-weight organic acids have the potential to remove Cu and Zn from swine manure. |
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