低分子有机酸去除猪粪中铜锌的效率研究

为探究低分子有机酸对猪粪中重金属的去除效果,通过振荡浸提法研究了柠檬酸、酒石酸、草酸和苹果酸在不同浓度、时间、pH值和固液比条件下对猪粪中Cu和Zn的去除效果。结果表明,猪粪中Cu、Zn的去除率均随有机酸浓度的增加呈线性上升趋势。当有机酸浓度为0.20 mol·L-1时,草酸作用下的Cu和Zn去除率分别为42.37%和47.63%,而柠檬酸作用下二者分别为27.19%、77.17%。动力学试验表明,猪粪中Cu、Zn去除率随反应时间的延长呈倒数上升趋势,在240 min时二者均达到较高去除率;Cu、Zn的去除主要在酸性条件下进行,在pH值为2.00时它们的去除率分别高达41.89%和68.14%,而后随pH值增加而迅速降低;固液比为1∶10时二者均可达到较高去除率。此外,猪粪经有机酸浸提后呈酸性,且TP和TK含量显著降低,分别为8.97~10.87 g·kg~(-1)和4.97~6.23 g·kg~(-1),但其TN含量无显著变化,且有机质含量相对略微增加。由此可知,低分子有机酸是一种能有效修复猪粪Cu、Zn污染的潜力材料。

Removal of copper and zinc from swine manure using low-molecular-weight organic acids

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.