Aerobic denitrification of a Pseudomonas sp. isolated from a high strength ammonium wastewater treatment facility

An aerobic denitrifier (termed X31 in this study) isolated from a wastewater treatment facility treating high strength ammonium wastewater was genetically identified, and morphologically and physiologically characterized. Its aerobic denitrification performance was also studied under various levels of DO, pH, temperature, and C/N ratios, as well as three carbon sources. Experimental results showed that: 1) the 16S rDNA of X31 has a 99% similarity to Pseudomonas stutzeri, but it is suggested to be a different strain due to its capability to carry aerobic denitrification at high DO levels that are normally inhibitory to P. stutzeri; 2) X31 is a mesophile and prefers a neutral to slightly alkaline environment to perform its aerobic denitrification process; 3) No NO₂^--N accumulation was observed during X31 aerobic denitrification process; 4) NO₃^--N removal by X31 appeared to be a zero-order reaction over NO₃^--N concentrations when X31 grows exponentially, which needs further investigation; 5) As a heterotrophic bacteria, X31 growths and utilization of NO₃^--N varied between different organic carbon sources.