Electrokinetic Remediation Of Pb Contaminated Soils

Many industrial enterprises in downtown appeared serious environmental problems for irrational economic structure and other reasons in China. A Pb resource recycling company, recycled a large number of waste batteries and stacked in the factory. Large amounts of heavy metals, acid and alkali solution oozed from waste batteries after a long period of mechanical wear and corrosion. These waste migrated into soil and caused heavy metal pollution, Pb concentration was 900-1800 mg/kg, it was substantially higher than the soil background values. This paper was based on the background, by the method of electrokinetic remediation and combined laboratory simulation and actual pollution to study the feasibility of electrodynamics remediation method, influence of remediation time, applied voltage, exchanging of electrode direction, intermittent electricity and cathode p H controlling on remediation efficiencies. The experiment tried to find out the best experimental conditions, and to research the influence on soil fertility. Through a series of experiments get the following conclusion:(1)Heavy metal removal rate increased with the increasing of remediation time and voltage, energy consumption increased too. When remediation time and voltage is 96 h, 1.0V/cm, Pb removal rate is 37.25%, energy consumption is 80.5 k W·h/g.(2)The method of exchanging electrode direction and intermittent electricity method are adopted to reduce energy consumption electricity and increase Pb removal rate. The best intermittent electricity method is on 24 h off 12 h on 24 h off 12 h on 24 h, Pb removal rate is 45.3%, energy consumption is 33.53 k W·h/g. Exchanging frequency is 48 h, Pb removal rate increase to 64.5%, energy consumption is 44.43 k W?h/g.(3)The method of cathode p H controlling can prevent the precipitation of heavy metals, Pb removal rate increased significantly, Pb removal rate is 74%, energy consumption is 32.6 k W?h/g. Under this conderation, the Pb removal rate is the highest and the energy consumption is the lowest, so the best experimental conderation is 1.0 V/cm, 96 h and 0.1mol/L HNO3 as cycle cathode liquid. The content of soil available nitrogen, available phosphorus and available potassium is increase to varying degrees. The average content of available nitrogen, available phosphorus and available potassium are higher than that of the initial content of 17.66 mg/kg, 37.25 mg/kg and 59.04 mg/kg.The results showed that electrodynamics remediation method not only can effectively remove heavy metals in soil, it can effectively improve soil fertility. It is a kind of environmental friendly technology, so the electrodynamics remediation method can be widely used in the remediation of agricultural soil and other types of contaminated soil.