Perchlorate Reduction by Autotrophic Bacteria in the Presence of Zero-Valent Iron

摘要

A series of batch experiments were performed to study the combination of zero-valent iron (ZVI) with perchlorate-reducing microorganisms (PRMs) to remove perchlorate from groundwater.In this method,H_2 produced during the process of iron corrosion by water is used by PRMs as an electron donor to reduce perchlorate to chloride.Perchlorate degradation rates followed Monod kinetics,with a normalized maximum utilization rate (r_(max)) of 9200 mug g~(-1) (dry wt) h~(-1) and a half-velocity constant (K_s) of 8900 mug L~(-1).The overall rate of perchlorate reduction was affected by the biomass density within the system.An increase in the OD_(600) from 0.025 to 0.08 led to a corresponding 4-fold increase of perchlorate reduction rate.PRM adaptation to the local environment and initiation of perchlorate reduction was rapid under neutral pH conditions.At the initial OD_(600) of 0.015,perchlorate reduction followed pseudo-first-order reaction rates with constants of 0.059 and 0.033 h~(-1) at initial pH 7 and 8,respectively.Once perchlorate reduction was established,the bioreductive process was insensitive to the increases of pH from near neutral to 9.0.In the presence of nitrate,perchlorate reduction rate was reduced,but not inhibited completely.