Heavy Metal Contaminated Soil Remediation Technology

Soil contaminated by heavy metals is one of the environmental problems that should be resolved urgently. Soil pollution is accumulative, lagging, dormant, and irreversible, therefore, soil pollution is usually difficult to be remedied and treated. This paper mainly studied phytoremediation and electroremediation of lead contaminated red soils. The studies based on the researches of at home and abroad and combined actual conditions.Elecreoremediation technique is an advancing task of global environment science and technology. Its principle is that: application of direct electric current via electrodes immersed in a saturated soil results in oxidation at the anode, generating an acid front that cause desorption and dissolution of heavy metals. The desorped and dissoluted heavy metals are migrated toward cathode reservoir by electric field and ions concentration grads by the means of electromigration, electroosmosis and diffusing.This paper is mainly about lead contaminated electroremediation techniques. The electroremediation technology is efficient to remedy Pb contaminated red soils; pH value of red soil is the major factor of dominating electroremedition, pH value of red soil can not only lead to high tank voltage and high temperature of red soil by means of decreasing electro-conductivity of soil, but also reduce remediation efficiency by precipitating Pb and then decreasing mobility of Pb. Hence, electroremediation techniques should be enhanced so as to apply to remedy Pb contaminated red soils. Control pH value of the cathode reservoir with HNOs can improve the removal efficiency, decrease cost of rememdiation and shorten duration of remediation.The absorption, concentration and phytoremediation of cadmium in soil, relationship between concentration of cadmium and enzyme activity in soil, and the effect of phytoremediation on enzyme activity in soil over time by pot-planting method were studied. Our results show that: plants have capacity of absorption, concentration and remediation on cadmium pollution in soil, but the capacity varies with different plant species; urease activity in soil decreases with the increase of cadmium concentration in soil;urease activity in soil is found to be closely correlative with concentration of cadmium in soil by regression analysis so that the urease activity can be used to indicate the degree of cadmium pollution in soil; the urease activity in soilpolluted by cadmium is recovered by phytoremediation, and the degree of phytoremediation can be judged according to the degree of recovery of the urease activity in the soil.