3种植物水浸提液对工业园区污水处理厂污泥中重金属的淋洗效果

为探讨植物材料淋洗去除工业园区污水污泥中重金属的可行性，选用马桑（Coriaria nepalensis）、枳椇子（Hovenia acerba）和乌药（Lindera aggregata）的水浸提液作为淋洗剂，采用振荡淋洗实验研究了不同淋洗剂浓度和pH、淋洗时间和温度对其去除供试污泥中重金属的影响，并确定淋洗的最佳参数。结果表明，当3种淋洗剂浓度从20 g·L-1上升到80 g·L-1或淋洗温度从15 ℃增至55 ℃时，重金属去除率均呈先升高后稳定的趋势。同时，淋洗效果还受淋洗剂pH和淋洗时间的影响。基于淋洗效果、技术应用和经济成本，枳椇子、乌药和马桑水浸提液淋洗的最佳参数分别为pH 7、80 g·L-1、25 ℃、180 min，pH 4、100 g·L-1、25 ℃、180 min和pH 4、80 g·L-1、25 ℃、180 min，此时各淋洗剂重金属去除率总体表现为Cd>Cu>Pb>Ni。其中枳椇子和乌药对Cd去除率较高，分别为73.12%和82.60%，但Ni去除率仅为23.34%和19.42%；与前2种植物材料相比，马桑对Pb（36.40%）和Ni（27.88%）的去除率高，但对Cd（30.11%）和Cu（30.38%）的去除率相对较低。淋洗后污泥中Cu和Pb含量均可达农用污泥A级标准（CJ/T 309-2009），乌药淋洗后Cd及马桑淋洗后Ni含量可达到A级标准，其他淋洗剂情况下Cd和Ni含量可达到B级标准。此外，植物水浸提液淋洗污泥还能有效保留甚至增加其养分，降低可交换态、碳酸盐结合态和铁锰结合态重金属含量。研究表明，马桑、枳椇子和乌药在淋洗去除污泥中重金属和实现污泥土地应用上有一定潜力。

Leaching of heavy metals from sewage treatment plant sludge in industrial park by three washing agents extracted from plant materials

To explore the feasibility of removing heavy metals from the industrial sludge by water extracts of plant materials, three water extracts of Coriaria nepalensis(CN), Hovenia acerba (HA) and Lindera aggregata(LA) were used to remove heavy metals from the industrial sludge at different concentrations and pH, reaction times and temperatures. The results show that the heavy metal removal efficiencies by these three agents first increased, and then tended to stabilize at the agent concentrations of 20 ~ 80 g·L-1 or the reaction temperature of 15 ~ 55 ℃. Meanwhile, the heavy metal removal efficiencies were also affected by the pH of agents and the reaction time. On the basis of the leaching effects, the technical application and the cost, the optimum parameters of leaching, such as pH, agent concentrations, reaction times and temperatures, were pH 7, 80 g·L-1, 180 min and 25 ℃ for HA, pH 4, 100 g·L-1, 180 min and 25 ℃ for LA, and pH, 4, 80 g·L-1, 180 min and 25 ℃ for CN. Under these conditions, the removal efficiencies of heavy metal for three agents were Cd>Cu>Pb>Ni. Among the three agents, HA and LA leaching presented 73.12% and 82.60% Cd removal, while 23.34% and 19.42% Ni removal, respectively. CN leaching caused 36.40% Pb and 27.88% Ni removal, but the relatively low removal efficiencies for Cd (30.11%) and Cu (30.38%). The residual Cu and Pb concentrations in leached sludge by the three extracts complied with the agricultural standard for sludges (class A) (CJ/T 309-2009). Relatively, Cd and Ni concentrations in leached sludge by LA and CN satisfied with class A, while their concentrations in the other cases complied with class B. In addition, the nutrients in plant water extracts leached sludge was effectively retained or even raised, and the heavy metals in the exchangeable fraction, carbonate-bound fraction and Fe-Mn oxides-bound fraction decreased. Therefore, CN, HA and LA leaching could be the potential to remove heavy metals from industrial sludge and reuse sludge for agriculture.