Application of zerovalent iron (Fe0) to enhance degradation of HCHs and DDX in soil from a former organochlorine pesticides manufacturing plant

Remediation of pesticide-polluted soil is particularly challenging when pesticides in soil are aged and a mixture of pesticides is present. Application of zerovalent iron (Fe0) was investigated to accelerate the degradation of HCHs (α-, β-, γ- and δ-hexachlorocyclohexane) and DDX (DDT, DDE and DDD) in the soil from a former organochlorine pesticide manufacturing plant. Ultrasonic extraction was used extract the organochlorine pesticides from soil. The identification and quantification of organochlorine pesticides in the extracts were accomplished by gas chromatograph. The addition of Fe0 facilitated the degradation of the β-HCH isomer, but had little effect on the degradation of α-HCH, γ-HCH and δ-HCH. Zerovalent iron significantly increased the degradation of p,p′-DDT and o,p′-DDT in soil, and the percentage degradation of p,p′-DDT and o,p′-DDT increased with increased Fe0 concentration during the first period of incubation. However, the amount of p,p′-DDD, the main dechlorinated product of p,p′-DDT, basically kept increased except in the unamended soil. The addition of Fe0 therefore did not increased the percent degradation of ∑DDT (p,p′-DDT + p,p′-DDD + p,p′-DDE) markedly.