The kinetic reaction of anaerobic microbial chloerobenzenes degradation in contaminated soil

Abstract

The kinetic reactions of hexachlorobenzene (HCB) and coexisting chlorobenzene congeners in real HCB-contaminated soil and effects of environmental factors on degradation rate, such as solid-liquid ratio, pH and incubation temperatures, were investigated. The Monod model was adopted for the kinetic study and the related kinetic parameters were evaluated. The Monod model showed good fitness for HCB degradation, not for coexisting chlorobenzene congeners. For pentachlorobenzene (PeCB), 1,2,4,5-tetrachlorobenzene(1,2,4,5-TeCB) and 1,2,4-trichlorobenzene(1,2,4-TCB), the calculated value of average degradation rate may not be “positive” or “negative” invariably, depending on production and degradation of these halogenated organic compounds. For HCB, a maximum degradation rate constant of 0.0359 d−1 and half-life time of 19.3 d were achieved, respectively. The hydrogen ion played the most important role in degradation of four chlorobenzenes. However, this role could be weakened if the solubility of compound was considered. Also, the results showed that the initial weak acid to neutral pH (5 – 7) environment with the incubation temperature of 45 °C was favorable for the rapid kinetic degradation of chlorobenzenes and the removal of chlorobenzenes was evaluated to reach 46%. This study offers direct kinetic behaviors and environmental factors analysis of the biodegradation process of HCB and coexisting chlorobenzene congeners, and is beneficial to explored the potential of optimized anaerobic microbial degradation for remediation engineering of chlorobenzenes contained soil.