Enhanced biological denitrification in the cyclic rotating bed reactor with catechol as carbon source

• The denitrification was evaluated in the CRBR using toxic carbon source.
• Optimum media filling ratio in the CRBR was found to be 30%.
• Minimum rotational speed of media in the CRBR was 20 rpm.
• CRBR reduced nitrate to the discharge limit at loading rate of 58 g/m3 h.
• CRBR attained the denitrification at a rate much greater than that in conventional bioreactors.

The performance of CRBR in denitrification with catechol carbon source is presented. The influence of inlet nitrate concentration, hydraulic retention time (HRT), media filling ratio and rotational speed of media on the performance of CRBR was investigated. The bioreactor could denitrify over 95% of the nitrate at an inlet concentration up to 1000mgNO3-/L and a short HRT as low as 18 h. The optimum media filling ratio at which the maximum denitrification was achieved in the CRBR was 30% and the contribution of media at this condition was around 36%. The optimum ratio of media filling at which the maximum denitrification was 20 rpm and the contribution of rotational speed under this condition was around 17%. According to the findings, the CRBR is a high rate bioreactor and thus serves as an appropriate technology for denitrification of wastewaters containing a high concentration of nitrate and toxic organic compounds.