Abstract:

The denitrification characteristics of an aerobic denitrifier,Pseudomonas chloritidismutans strain X31,Were studied under aerobic conditions.The results show that:(1)the dentitrification process of X31 mainly occurs in the LOG phase of the strain and the major end product of the denitrification is molecular nitrogen,(2)during the denitrification of X31,the pH in the culture medium gradually increases,while the Oxidation-reduction Poten-tial gradually decreases,(3)X31 can co-respire by using nitrate or nitrite and oxygen as the electron acceptor,and (4)nitrite respiration is easier than nitrate respiration,both of which achieve high nitrogen removal rate.It is also shown that X31 possesses a higher tolerance to dissolved oxygen than other aerobic denitrifiers reposed previously,and that,when the initial mass concentration of nitrogen oxides in the cuhure medium is about 1 50 mg/L,the aero-bic denitrification rate of the strain is not obviously affected by dissolved oxygen.

Key words: aerobic denitrification, nitrate respiration, nitrite respiration, biological nitrogen removal, co-respira-tion, electron acceptor