In-situ remediation of heavy metal-contaminated soil using multifunctional biochar

Abstract

The invention relates to a method for repairing heavy metal contaminated soil in situ by adopting multifunctional biological charcoal. According to the technical scheme, the multifunctional biological charcoal is prepared from biological waste such as straws and sawdust, the surface of the multifunctional biological charcoal is provided with multiple surface functional groups and rich enterable micropores, the heavy metal contaminated soil of which the relative humidity is 60-90% is turned over and mixed with the multifunctional biological charcoal of which the granularity is 0.074-0.178mm, the turnover mixing depth is 5-30cm, and the soil can be repaired after being aged for 20-30 days. The mass ratio of the multifunctional biological charcoal to the heavy metal contaminated soil is (0.1-5) to 100. The multifunctional biological charcoal serving as a soil additive in the in-situ repairing process can effectively fix heavy metals in the soil, improve the ecological environment, supplement organic charcoal, protect the soil health, reduce the toxicity of the contaminated soil and restore the productivity of the soil; and the method is also applicable to engineering repairing of water bodies and solid matrixes.

Description

technical field [0001] The invention belongs to the technical field of in-situ remediation of heavy metal polluted soil. Specifically, it relates to a method for in-situ remediation of heavy metal-contaminated soil by using multifunctional biochar. technical background [0002] Heavy metals mainly refer to elements with a specific gravity greater than 5, such as chromium, lead, cadmium, mercury, copper, arsenic and other metal elements with significant biological toxicity. With the rapid development of my country's industry, more and more unreasonable discharges of waste water and residues in industries such as electroplating, steel and dyes have formed a severe situation of heavy metal pollution in soil and water. Heavy metal ions are chemically stable and cannot be degraded by microorganisms, and can also be enriched in organisms through the food chain. [0003] There are a variety of substances in the human body, including protein, which is composed of a variety of amin...

AI Technical Summary

Problems solved by technology

For example lime is a kind of effective fixing agent, by improving soil pH value, reduces heavy metal solubility, effectively reduces the mobility of heavy metal (Zhang Xiaoxi, the impact of lime on cadmium form and mustard cadmium absorption on heavy metal polluted soil, 2003, 18 (3 ): 151~154), but for metal ions with good water solubility under alkaline conditions such as arsenic and chromium, the effect of reducing toxicity cannot be achieved

Organic matter such as sawdust, chaff, and poultry manure can bind heavy metal ions to a certain extent, limit the activity of heavy metals, and increase the fixation rate of heavy metals. However, with the decomposition of organic matter under the long-term action of the environment, the large amount of volatile organic carbon can effectively stimulate microorganisms. The active development of organic carbon accelerates the mineralization of organic carbon and releases CO 2 (J.R.Quilty and S.R.Cattle, Use and understanding of organic amendments in Australian agriculture: a review, Soil Res. 49:ppl-26, 2011)

Heavy metals will be released again, which cannot solve the problem of heavy metal pollution in a long-term and stable manner