关键词: 铬污染土, CaS₅, 粉煤灰合成沸石, 水泥, 正交试验, 微面特性

Abstract: Single reduction method and solidification/stabilization technology are inefficient in dealing with chromium polluted soil. A method combining pollution reduction and soil solidification/stabilization is presented in this paper. The optimum mix proportion of the compound treating agent composing reducing agent, adsorbent and curing agent was determined through single-doping test and L₉(3⁴) orthogonal test. The solidified/stabilized chromium contaminated soil was microscopically characterized by scanning electron microscopy. Results show that the optimum mix proportion of the compound is: the dosage of calcium polysulfide is three times the theoretical reducing dosage required to reduce Cr(VI) in the contaminated soil to Cr(Ⅲ) , synthetic zeolite content is 15%, and cement content is 20%. SEM analysis demonstrates that the compound alleviates the blocking effect of Cr(VI) and Cr(Ⅲ) on hydration reaction and coagulation reaction through the combined actions of reduction, adsorption, and solidification, and strengthens the curing/stabilizing effect. It also has evident effect of reducing the leaching concentration of the cured body, with the toxic leaching result meeting standard requirements.

Key words: chromium contaminated soil, CaS₅, zeolite synthesized from coal fly ash, cement, orthogonal test, micro-characteristics