SIMULTANEOUS NITRIFICATION AND DENITRIFICATION IN AN MBR TREATING COPPER BEARING SYNTHETIC MUNICIPAL WASTEWATER

The growing interest towards combining municipal and industrial wastewater as well as the increasingly stringent discharge criteria would make membrane bioreactors (MBRs) a potential option for the treatment of heavy metal bearing municipal wastewaters. While nitrogen removal through simultaneous nitrification denitrification (SND) could be more efficient in utilizing the aerobic tank volume for nitrogen removal in MBRs, the lower oxygen transfer efficiency at high mixed liquor concentrations may be favorable to achieve SND. This study showed that achievement of SND in submerged MBRs through DO control is not a stable and reliable option. These results suggested that compartmentalized tanks would be a more viable option to achieve biological nitrogen removal in treatment plants employing submerged MBRs. While the system adapted to 8 mg/L feed copper, the 30% loss of SND was attributed to the reduced floc size and not toxicity. Using respirometric batch studies, the specific maximum substrate utilization rate (k) was found to be 2.13 gNH4-N/g.d at zero copper but decreased by 47% at 30 mg/L total initial Cu.