Abstract:In this study, the cyanide-polluted soil was taken as the research object, the joint process of oxidation and flushing techniques was used to restore it. The relationship between the cyanide form transformation and remediation effects was investigated at different oxidant dosages and flushing times. Due to the reducibility and high-solubility, the cyanide in soil was removed by means of oxidative decomposition and dissolution. The results showed that the total cyanide in soil decreased, the cyanide changed from complexing form into easy-release one, and the total cyanide content in soil leaching solution increased firstly and then decreased with the increase of oxidant dosage under the oxidation conditions. At the oxidant dosage of 5%, the total cyanide concentration decreased from 51.2 mg·kg?1 to 9.23 mg·kg?1 which met the remediation target. However, the total cyanide concentration in soil leaching solution decreased from initial 1.6 mg·L?1 to 0.79 mg·L?1 which could not meet the remediation target. When the soil was flused for 5 times under shaking conditions, the total cyanide in soil decreased, and the easy-release cyanide form also gradually decreased, and the total cyanide in soil leaching soultion decreased rapidly with the increase of the elution times. After three times-elution, the total cyanide concentraion in soil leaching solution decreased from 1.6 mg·L?1 to 0.04 mg·L?1 which met the remediation target. However, the total cyanide concentration in soil decreased from 51.2 mg·kg?1 to 10.2 mg·kg?1 which could not meet the remediation target. When oxidation and flushing techniques were jointly used, the dual remediation targets of total amount of 9.86 mg·kg?1and leaching amount of 0.1 mg·L?1 were met in the actual project with the oxidant dosage of 3% and one time-elution. The joint oxidation and flushing techniques in this study was feasible to restore the cyanide-contaminated soil. Key words:contaminated soil/ cyanide/ oxidation/ flushing.
图1氧化剂用量对土壤中氰化物形态的影响 Figure1.Impact of oxidant amount on cyanide form
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1.Tianjin Eco-City Environmental Protection Ltd. Co., Tianjin 300480, China 2.Tianjin Contaminated Site Remediation Technology Engineering Center, Tianjin 300480, China Received Date: 2019-12-01 Accepted Date: 2020-05-10 Available Online: 2020-11-11 Keywords:contaminated soil/ cyanide/ oxidation/ flushing Abstract:In this study, the cyanide-polluted soil was taken as the research object, the joint process of oxidation and flushing techniques was used to restore it. The relationship between the cyanide form transformation and remediation effects was investigated at different oxidant dosages and flushing times. Due to the reducibility and high-solubility, the cyanide in soil was removed by means of oxidative decomposition and dissolution. The results showed that the total cyanide in soil decreased, the cyanide changed from complexing form into easy-release one, and the total cyanide content in soil leaching solution increased firstly and then decreased with the increase of oxidant dosage under the oxidation conditions. At the oxidant dosage of 5%, the total cyanide concentration decreased from 51.2 mg·kg?1 to 9.23 mg·kg?1 which met the remediation target. However, the total cyanide concentration in soil leaching solution decreased from initial 1.6 mg·L?1 to 0.79 mg·L?1 which could not meet the remediation target. When the soil was flused for 5 times under shaking conditions, the total cyanide in soil decreased, and the easy-release cyanide form also gradually decreased, and the total cyanide in soil leaching soultion decreased rapidly with the increase of the elution times. After three times-elution, the total cyanide concentraion in soil leaching solution decreased from 1.6 mg·L?1 to 0.04 mg·L?1 which met the remediation target. However, the total cyanide concentration in soil decreased from 51.2 mg·kg?1 to 10.2 mg·kg?1 which could not meet the remediation target. When oxidation and flushing techniques were jointly used, the dual remediation targets of total amount of 9.86 mg·kg?1and leaching amount of 0.1 mg·L?1 were met in the actual project with the oxidant dosage of 3% and one time-elution. The joint oxidation and flushing techniques in this study was feasible to restore the cyanide-contaminated soil.