In order to clarify the effect of biochar-polylactic acid (PLA) composite on reductive dechlorination of HCB in paddy soils, an anaerobic incubation experiment was conducted with four treatments of Sterile control, Control, Biochar, and Biochar-PLA in Hydragric Acrisols (Ac) and Gleyi-Stagnic Anthrosols (An). The results showed that in Ac, biochar addition significantly promoted HCB degradation during the whole incubation period, but biochar-PLA composite inhibited HCB dechlorination due to the low soil pH in the early period and then accelerated HCB degradation while soil pH climbed to nearly neutral. The dechlorination rate of HCB in An was: Biochar-PLA > Biochar > Control > Sterilization control. The degradation rate of HCB in An was faster than in Ac, due to the higher iron content and neutral pH condition in An. The results indicated that biochar-PLA composite promoted the reductive dechlorination of HCB efficiently in paddy soil under nearly neutral pH condition.
Keywords: Biochar; Hexachlorobenzene; Paddy soil; Polylactic acid; Reductive dechlorination.