Redox potential as a controlling factor in enhancing carbon tetrachloride biodegradation

Abstract

Biodegradation of hazardous waste is often the most cost-effective technique suitable for purifying large quantities of polluted groundwater and industrial effluents. In an effort of optimizing environmental conditions for microorganisms to degrade carbon tetrachloride, culture redox potential (Eh) was demonstrated as having a critical role. The microorganisms tested were isolated from contaminated field sites and included Pseudomonas cepacia and Providencia stuartii . Ti(III) citrate was used as a reducing agent to poise Eh at designed values. Over 99% degradation of carbon tetrachloride was effected in 3 days at −250 mV ≤ Eh ≤ −200 mV. Lesser rates were observed at Eh ≥ 0 mV. Kinetic analysis indicated that the overall degradation rate constant increased from 2.75×10−3 h−1 to 4.75×10−2 h−1 by controlling Eh at about −200 mV compared with Eh at ≥ 0 mV. Results indicated that the implementation of critical redox potential may be effective in optimizing CT biodegradation activity.