Washing treatment method for heavy metal contaminated soil

Abstract

The invention provides a washing treatment method for heavy metal contaminated soil. The method comprises the following steps: mixing the heavy metal contaminated soil and water, sieving the heavy metal contaminated soil with water, feeding the sieved soil to a washing tank, injecting a washing solution, performing circulation stirring, detecting the washed soil till the soil is qualified, dehydrating the qualified soil which is treated in the previous step, adding borrowed soil to the dehydrated soil, and then performing backfilling. The method is simple to operate, adopted reagents are common and available, the implementation cost is low, the removal rates of Cd, Zn, Pb and Cu in the soil can respectively reach 65.1, 47.5, 43.2 and 35.1 percent, the removal rates are superior to that inthe existing treatment technology, and the method is flexible to use, can achieve the effects of improving the physical and chemical properties of soil and enhancing the soil fertility through addition of organic fungi-manure to the treated soil according to the requirements, overcomes the deficiency of long phytoremediation cycle on the heavy metal contaminated soil, and is low in environmental risk.

Description

technical field [0001] The invention belongs to the field of contaminated soil treatment, and in particular relates to a leaching treatment method for heavy metal-contaminated soil. Background technique [0002] Soil is the material basis for sustainable economic and social development, and protecting the soil environment is an important part of promoting the construction of ecological civilization and maintaining national ecological security. [0003] Among the heavily polluted pollutants, heavy metals are the main source of pollution. Due to human activities, the content of trace metal elements in the soil exceeds the background value, and excessive deposition causes the content of heavy metals in the soil to be too high, resulting in heavy metal pollution in the soil. Heavy metals refer to metals with a specific gravity equal to or greater than 5.0, mainly including elements with significant biological toxicity such as cadmium, mercury, lead, chromium, and metalloid arse...

AI Technical Summary

Problems solved by technology

Use the composite bacteria solution obtained from the cultivation of composite bacteria to spray the chromium slag stockpile soil or slag soil, and the pentavalent Cr in the obtained eluent is reduced to trivalent Cr, and precipitates are formed under alkaline conditions, and the chromium is recovered by the precipitation, and the soil Or the tetravalent Cr that was not leached out of the dregs was chemically fixed by hydrazine hydrate. Using this method to remediate the soil and dregs with three different levels of tetravalent Cr pollution, the removal rates of total chromium reached 11.4%, 30.2% and 14.0%, the removal rate of water-soluble tetravalent Cr has also reached 99.6%, 99.5% and 98.3%, respectively, and the leaching toxicity concentration of tetravalent Cr in soil and dregs is lower than 0.5mg / L, but the treatment efficiency of this method is limited The height is subject to the concentration and activity of the two bacterial colonies

CN104668281A discloses a chemical leaching-phytoabsorption combined restoration method for acidic soil heavily polluted by cadmium in non-ferrous metal mining and metallurgy areas in southern China. Pour the ferric chloride solution over the soil, and the liquid will naturally flow out from the bottom of the soil column with gravity to remove most of the active cadmium in the soil. After the eluent above the soil has completely infiltrated into the soil, pour deionized water on top of the soil , the liquid naturally flows out from the bottom of the soil column with gravity to remove the residual cadmium and leaching agent in the soil, and then the above-mentioned leached soil is dried, ground, and sieved, and quicklime, sepiolite, commercial organic Fertilizer and total nutrient (N+P2O5+K2O) are improved, continuous planting of sedum sedum for 1 to 5 seasons and completion of restoration after harvesting aboveground plants, the method provided by the invention is simple in principle, but the cycle is long, planting sedum and the workload of harvesting plants is greater

[0005] In summary, there is currently no fast, low-cost and specific treatment method for heavy metal-contaminated soil.

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