Investigating the nitrification and denitrification kinetics under aerobic and anaerobic conditions by Paracoccus denitrificans ISTOD1.

Municipal wastewater contains multiple nitrogen contaminants such as ammonia, nitrate and nitrite. Two heterotrophic nitrifier and aerobic denitrifiers, bacterial isolates ISTOD1 and ISTVD1 were isolated from domestic wastewater. On the basis of removal efficiency of ammonia, nitrate and nitrite under both aerobic and anaerobic conditions, ISTOD1 was selected and identified as Paracoccus denitrificans. Aerobically, NH4+-N had maximum specific nitrogen removal rate (Rxi) of 7.6g/gDCW/h and anaerobically, NO3-N showed Rxi of 2.5*10-1g/g DCW/h. Monod equation described the bioprocess kinetic coefficients, µmax and Ks, obtained by regression. Error functions were calculated to validate the Monod equation experimental data. Aerobic NO3-N showed the highest YW of 0.372mg DCW/mg NO3-N among the five conditions. ISTOD1 serves as a potential candidate for treating nitrogen rich wastewater using simultaneous nitrification and aerobic denitrification. It can be used in bioaugmentation studies under varied condition.