BACKGROUND: Contamination of nitrate in ground and surface water has become an ever-increasing and serious environmental problem. Biological methods hold the promise of converting nitrate into harmless nitrogen. A novel denitrification system which combines proton-exchange membrane electrodialysis with simultaneous bio-electrochemical autotrophic denitrification has been developed. The proton-exchange membrane was used to transfer current and to exclude oxygen or other oxidative chemicals generated in the anode reaction. The H(2) generated by the cathode was utilized by autotrophic denitrifying microorganisms in the cathode cell to reduce nitrate. In this study, the transport of H(+), a denitrification kinetics model and factors influencing the denitrification rate were explored in batch mode. RESULTS: The addition of 0.03 mol L(-1) H(2)SO(4) into the anode cell enhanced proton transport and maintained the pH of the cathode cell in an appropriate range for biological denitrification. The denitrification rate was affected by applied current and biomass. Under adequate current conditions, the kinetics of the denitrification process followed a zero-order kinetics model; the average denitrification rate for unit biomass was calculated to be 9.36 mg NO(3)(-)-N VSS g(-1) h(-1). CONCLUSIONS: Results indicate that the system is suitable for denitrification. Owing to its simple structure and operation, it has the potential for use as a system to reduce nitrate in water. (C) 2010 Society of Chemical Industry
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