Method and device for biochemically recharging and restoring polluted soils in chromium slag yard

Abstract

The invention discloses method and device for biochemically recharging and restoring polluted soils in a chromium slag yard. The device comprises a soil treatment groove containing soils to be treated, a middle pond, a biochemical pond and a bacteria culture pond. Every two parts are connected through a water pipe, chromium polluted soils are installed in the soil treatment groove to be heaped after being crushed by a 2cm sieve, the height of a mound is smaller than 0.8m, and the soils are sprayed by Cr (VI) reducing bacteria (Pannonibacter phragmitetus BB) culture medium with the spraying strength of 0.008-0.015m<3> / h.m<2>; and leachate is collected from the bottom of a soil groove to the middle pond, bacterial liquid in the middle pond is pumped into the biochemical pond by an alkali resistance pump, and bacterial liquid in the biochemical pond circulates again to be used for spraying the soils and is in circulating spraying for 5-7 days until the soil leachate does not contain Cr (VI). By adopting the invention to restore the polluted soils in the chromium slag yard, the removal rate of water-soluble Cr (VI) in the soils achieves 99 percent, and the concentration of Cr (VI) leaching toxicity in the soils after restoring is lower than 0.5mg / L and achieves a standard limited value of roadbed materials and concrete aggregates in Technical Specifications for Chromium Slag Pollution Control (HJ / T301-2007). Simultaneously, the invention has the advantages of having simple technology, low cost and no secondary pollution, improving the physicochemical property of the soils, and the like.

Description

technical field [0001] The invention belongs to the field of environmental engineering, and in particular relates to a method and device for remediating chromium-contaminated soil, in particular to a biochemical recharge method and device for remediating heavily polluted soil in chromium slag yards. Background technique [0002] Chromium pollution is a serious environmental problem in my country. Its pollution mainly comes from the discharge of a large amount of waste residue and waste water in industries such as chromium salt, electroplating, tanning, fuel, pigment and organic synthesis. As far as chromium salt production is concerned, there are 63 sites in 24 provinces (municipalities directly under the Central Government) that have chromium salt production plants, of which 18 are still in production; 27 have been closed or bankrupt but still have chromium slag; 18 companies have gone bankrupt or closed down, and chrome slag has been disposed of. More than 12.5-15 million...

AI Technical Summary

Problems solved by technology

However, these methods have their own limitations: the cost of immobilization / stabilization method is high, and the treatment effect is not good; the chemical reduction method is easy to cause secondary pollution of the soil, and how to remove the hexavalent chromium in the soil is the key to this technology. Difficulties; the chemical cleaning method is only suitable for soil with a large permeability coefficient (such as sandy soil, etc.), and it is easy to cause secondary pollution of the soil when the cleaning solution is introduced; the electrodynamic repair method has strict requirements on soil conditions and expensive repair costs

Although many Cr(VI)-reducing bacteria have been isolated, there is no report on the engineering restoration of chromium-contaminated soil

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