High-rate biological denitrification in the cyclic rotating-bed biological reactor: Effect of COD/NO3-, nitrate concentration and salinity and the phylogenetic analysis of denitrifiers

The effects of COD/NO3- ratio, nitrate concentration and salinity was tested on the performance of the CRBR in denitrification with catechol as carbon source. The maximum nitrate reduction attained at COD/NO3- ratio of 1. The CRBR operated at optimum COD/NO3- ratio could completely denitrify the nitrate at inlet concentration up to 1250 mg/L without nitrite accumulation. The maximum denitrification rate in the CRBR was 3.56kgNO3-/m3d with a nitrate reduction efficiency of 99% when the bioreactor was operated at inlet nitrate loading rate of 3.6kgNO3-/m3d. The denitrification performance of the CRBR was not affected significantly by NaCl concentrations up to 20 g/L. 16S rRNA fragment and phylogenetic analysis identified Pseudomonas resinovorans, Stenotrophomonas maltophilia and Bacillus cereus as the most abundant denitrifiers in biomass. Accordingly, the CRBR is a high-rate bioreactor and appropriate technology for treatment of nitrate-laden industrial wastewaters containing phenolic compounds and salinity.