| OGO process has been formed as a modification of OCO process through test research. As a advanced technology, it has the functions of phosphorus removal and denitrification with facilitation,effectiveness and economy. OGO technology has already been approved as Utility Model Patent(ZL2005 2 0010545.7)and Invention Patent(ZL2007 1 0092501.7). According to the characteristic of OGO system, the dissertation carried out test and analysis on screening, nitrogen removal characteristics of aerobic denitrifying bacteria.The followings were studied:①Appropriate and special medium were chosen for primary screening of aerobic denitrifying bacteria, and which originated from activated sludge in OGO reactor possessing simultaneous nitrification and denitrification (SND) phenomenon;②Aerobic denitrification activity were tested firstly, then physiological -biochemical characteristics were studied and molecular biological were identified for these screened strains with higher activity of aerobic denitrification;③The degradation characteristic of nitrogen-containing simulated wastewater treated with these screened aerobic denitrifying bacteria were studied;④Nitrogen removal efficiency of activated sludge system intensified by these screened aerobic denitrifying bacteria were studied;⑤Treatment efficiency of OGO reactor intensified by these screened aerobic denitrifying bacteria were studied;According to the above study results, some conclusions are as follows:1) Aerobic denitrifying bacteria are existed in OGO reactor, strains of T3,T6,T7 can be determined as tested strains after many times screening, these tested strains with better nitrogen removal efficiency, 133.00mg/L NO3- can be removed to 60.26mg/L,55.11mg/L,50.47mg/L for strains of T3,T6,T7 and the average removal efficiency is 54.69%,58.56%,62.05% respectively. Besides, the maximum NO2- accumulation is low than 0.6mg/L. Influencing factors of nitrogen removal experiment results indicate that the optimum pH for the growth of bacteria is 7, temperature is 30℃and C/N ratio is 5;2) Strains of T3,T7 identified as Rhodococcus and T6 identified as Gordonia according to their morphological, physiological-biochemical reactions and 16S rDNA sequence homology comparison. Characteristics of T3,T7 are similar to the previous reported aerobic denitrifying bacterium of Rhodococcus sp.. The creditability of identification reaches to 99%;3) With two different modes of bacteria dropping, different concentrations of nitrogen-containing wastewater can be treated, and the difference of nitrogen removal efficiency is very significant. The experimental results indicate that the mode of dropping bacteria immobilized by polyvinyl alcohol (PVA) is superior to free (non-immobilized) bacteria;4) Mixed culture of T3,T6,T7 strains are dropped to activated sludge system, and the intensifying effect is different for mixed strains dropping volume. The removal efficiency of total nitrogen (TN) is 42.95% while mixed strains are not dropping, and it is 57.91% while 5% mixed strains are dropping. Therefore, nitrogen removal efficiency of activated sludge can be intensified by aerobic denitrifying bacteria;5) Intensifying effect of OGO reactor is different for dropping modes of mixed strains, the treatment effect for the mode of dropping mixed strains immobilized by PVA is superior to free(non-immobilized) mixed strains, and the average removal efficiency of COD,ammonia nitrogen (NH4+-N) and TN are 98.48%,90.18%,78.92% respectively, and compared with not intensifying, 4.21%,6.43%,4.61% is increased respectively. Therefore, the method of using aerobic denitrifying bacteria to improve the treatment effect of OGO reactor is feasible.The study is funded by International Science and Technology Cooperation Projects(2007DFA90660)and Scientific and Technical Key Task of Plan Projects in Chongqing(CSTC,2006AA7003-1). Besides, it is a part of the project"Treatment technique research of municipal sewage based on ideal flow pattern(50378095)", which is funded by state's natural science foundation. This research acquired the values of important parameters that could be used in actual design and control as well as provide technical support for the engineering utilization of aerobic denitrifying bacteria in municipal wastewater treatment.
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