有机酸对猪粪中重金属的浸提

Removal of heavy metals from pig manure by organic acids

为了解有机酸对猪粪中重金属的去除效果,以天津某畜禽养殖场猪粪为研究对象,利用化学浸提法,考察了柠檬酸、草酸、酒石酸和苹果酸四种有机酸对去除猪粪中重金属Cu、Zn和Mn的影响,确定了最佳有机酸种类和运行条件,并分析了有机酸的浸提成本和后续猪粪的农用性能。结果表明,柠檬酸和草酸对重金属的去除效果较好,在最佳条件下,柠檬酸对重金属Cu、Zn和Mn的去除率分别为57.90%、73.76%、79.56%,草酸对重金属的去除率分别为62.72%、59.39%、40.04%。有机酸以去除有机结合态Cu为主,而碳酸盐结合态、铁锰氧化物结合态和有机结合态的Zn、Mn重金属浓度都显著降低。重金属去除成本随固液比的降低而升高,固液比为1∶5时,柠檬酸和草酸对重金属的处理成本分别为126.07、384.24元·t^(-1)。浸提后猪粪中有机质、氮、磷、钾含量分别约为815.80、17.61、5.49、0.36 g·kg^(-1)。研究表明,柠檬酸和草酸浸提能较为有效地去除猪粪中的重金属,且浸提后的猪粪仍具有较高的营养价值和肥力。

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 ob-tained 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 and62.72%, 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^-1respectively. 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.