Based on the chlorinated organic compounds pollution existed in underground water of China, Zero-Valent-Iron (ZVI) technology is employed for the removal of four representative halogenated organic compounds (HOCs) (tetrachloroethylene, PCE; tricholoroethylene, TCE; tetrachlormethane, TCM; and chloroform, CT). The results indicated that the reduction rates of four target compounds, of which the initial concentration is 400 μg/L, negatively correlated with the size of Zero-Valent-Iron particles. The reduction kinetics of the targeted HOCs were all well fitted with the Pseudo-firstorder kinetics, and the ranking of obtained first order rate constants (K) among different particle sizes was K20nm>K100nm>K10μm>K100μm. Comparing K among four target HOCs, the reduction rates of chlorinated methane (CT, TCM) are higher than chlorinated ethylene (PCE, TCE), and highly chlorinated HOCs (PCE, CT) were degraded more easily than lower one (TCE, TCM). pH of aqueous solution all increased along the chlorinated compounds reduction which was raised by the reaction between ZVI and water. The oxygen in water consumed the ZVI particle either and competed with the surface adsorbed chlorinated compounds. In summary, Zero-Valent-Iron proved to be an efficient technology for typical HOCs removal, which can be considered as a promising process added in the beginning part of drinking water treatment plant.
The authors investigated the bioaugmentation performances of a selected bacterial strain for denitrification in a packed bed bioreactor using PBS as solid carbon source. Fluorescence quantitative PCR was employed to analyze the microbial community composition in the bioreactor. Results indicated that the denitrifier named W14 could remarkably improve denitrification efficiency. At HRT of 0.5 h, nitrogen removal was found to be higher than 90% and the residual DOC of effluent was greatly reduced. Addition of selected denitrifiers led to an increase of nirS gene abundance and proportion, indicating that inoculation of selected bacterial strain could boost denitrifiers’ proliferation and enhance nitrogen removal eventually.
