电动力修复Pb污染土壤的实验研究

发布时间：2018-08-17 15:04

【摘要】：上个世纪我国工业快速发展,因规划设计和经济结构不合理等原因,至使一些处于城区内的生产场地出现了环境问题。某公司大量回收废旧电池堆放于厂区内,经机械磨损和腐蚀,大量重金属及酸等电解质溶液渗出,致使堆放场地的重金属污染,经测定其中Pb含量高达900-1800mg/Kg,严重超出土壤背景值。本文采用电动力学法通过实验室模拟和实际污染相结合的方法,考察电动力学修复该污染土壤的可行性,研究了电动力修复时间、电压梯度、交换电极方向、间歇通电和阴极p H值控制对重金属去除效果的影响,并在最佳实验条件下,研究电动力修复对土壤土壤肥力的影响。通过一系列的实验研究得到以下结果:(1)重金属Pb去除率随修复时间及电压的增大不断升高,电能消耗随之增高。当修复时间和电压为96h、1.0 V/cm时,土壤中Pb从1500mg/kg降为941mg/kg,去除率为37.25%,电能消耗80.5 k W·h/g。(2)间歇通电和交换电极方向修复方式可以有效降低电能消耗,提高重金属去除率。实验得到最佳间歇通电方式为通24h停12h通24h停12h通24h,此种修复方式下重金属去除率45.3%,电能消耗33.53k W·h/g。实验设定交换电极方向频率为48h,此条件下Pb去除率升高到64.5%,电能消耗为44.43 k W·h/g。(3)阴极p H控制方式可有效防止阴极p H值过高导致的重金属沉淀,土壤中Pb去除率大幅度提高,由1500mg/kg降为390mg/kg,去除率为74%,电能消耗32.6k W·h/g。在此修复方式下,Pb去除率最高且能耗最低,因此确定最佳实验条件为电压1.0 V/cm、时间96h、0.1mol/L HNO3为循环阴极液。此条件下土壤中速效氮、速效磷、速效钾含量均有不同程度的升高,修复后速效氮、磷、钾平均含量分别高于初始含量17.66mg/kg,37.25mg/kg,59.04mg/kg。研究表明,电动力修复不但可以有效去除土壤中重金属,还可有效提高土壤肥力,是一种环境友好的修复技术,因此电动力修复还可广泛应用于农用土壤及其他类型污染土壤的修复。
[Abstract]:The rapid development of China's industry in the last century caused environmental problems in some production sites located in urban areas due to unreasonable planning and design and economic structure. A large number of recycled batteries were stacked in the factory area, and after mechanical wear and corrosion, a large number of heavy metals and acid electrolyte solutions seepage out, resulting in heavy metal pollution in the storage site, the Pb content of which is as high as 900-1800 mg / kg, which seriously exceeds the soil background value. In this paper, the feasibility of electrodynamic remediation of contaminated soil was investigated by means of laboratory simulation and actual pollution. The time of electrodynamic remediation, voltage gradient and the direction of exchange electrode were studied. The effects of intermittent electrification and cathodic pH control on the removal of heavy metals were studied. Under the optimum experimental conditions, the effects of electrodynamic remediation on soil fertility were studied. The following results were obtained through a series of experimental studies: (1) the removal rate of heavy metal Pb increased with the increase of repair time and voltage, and the power consumption increased. When the repair time and voltage were 96 h ~ (-1) V/cm, the Pb content in soil decreased from 941 mg / kg to 941 mg / kg, the removal rate was 37.25%, and the power consumption was 80.5 kW 路h / g 路g. (2) intermittent electrification and repair in the direction of exchange electrode could effectively reduce the power consumption and increase the removal rate of heavy metals. The results showed that the best intermittent mode of power supply was 24 h, 12h, 12h, 24h, and the removal rate of heavy metals was 45.3%, and the energy consumption was 33.53kW / h 路g. When the direction frequency of the exchange electrode is set at 48 h, the removal rate of Pb is increased to 64.55.The power consumption is 44.43 kHz / g. (3) the cathodic pH control method can effectively prevent heavy metal precipitation caused by excessive cathodic pH value, and the removal rate of Pb in soil can be greatly increased. The 1500mg/kg is reduced to 390 mg / kg, the removal rate is 74%, and the power consumption is 32.6 kh / g. In this way, the removal rate of Pb is the highest and the energy consumption is the lowest. Therefore, the optimum experimental conditions are as follows: voltage 1.0 V / cm, time 96 h 0.1 mol / L HNO3 as circulating cathode solution. Under this condition, the contents of available nitrogen, available phosphorus and available potassium in soil were all increased in varying degrees. The average content of available nitrogen, phosphorus and potassium after restoration was higher than that of initial content of 17.66 mg / kg ~ 37.25 mg / kg ~ (-1) ~ 59.04 mg / kg ~ (-1) 路kg ~ (-1). The results show that electrodynamic remediation can not only effectively remove heavy metals in soil, but also improve soil fertility effectively. It is an environmentally friendly remediation technology. Therefore, electrodynamic remediation can also be widely used in agricultural soil and other types of contaminated soil remediation.
【学位授予单位】：中国矿业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X53

【参考文献】