[Development of coated electrode of immobilized denitrifying bacteria and bio-electrochemical denitrifying reactor]

A coated electrode of immobilized denitrifying bacteria was developed to study the feasibility of electrochemical denitrification.

The coated electrode of denitrifying bacteria was made by batch cultivation and PVA immobilization using activated carbon fiber (ACF). The coated ACF electrode was used as cathode, while graphite as anode in bioelectrochemical reactor.

After having been acclimated in two stages, mixotrophic and autotrophic denitrification stages, the denitrifying bacteria could use hydrogen as electron donor to reduce nitrate. When the initial nitrate concentration was 30.7mg NO3- -N/L, the denitrification rate was 38.4% at an applied electric current of 10mA and a hydraulic retention time of 12 hours.

With great surface area and a rough surface, it was very easy to develop a biofilm on ACF. The membrane of PVA gel could adhere to the surface of ACF firmly. After having been acclimated, the denitrifying bacteria could use hydrogen generated by the electrolysis of water to be treated as electron donor to reduce nitrate.