Study On The Removal Of Nitrogen And Phosphorus Removal In SUFR-UCT System Based On Spiral Up Flow

On the basis of preliminary studies, spiral up flow technology was combined with the UCT process to study the phenomenon of SND and denitrifying phosphorus removal, the factors affecting nitrogen and phosphorus removal and the best conditions for nitrogen and phosphorus removal. The activated sludge were studied too. Aerobic denitrifies and phosphorus accumulating bacteria were isolated selected and identified. Detailed work and major conclusion are as follows:?The SUFR -UCT system based on spiral up flow could obtain high removal efficiency of phosphorus COD and nitrogen. The effluent concentration of COD was in the rage of 6~24mg/L, the effluent concentration of phosphorus was in the rage of 0.01~0.41mg/L, the effluent concentration of nitrogen was in the rage of 2.57~11.52mg/L. The COD were removed in the anaerobic reactor 87% of the total. There were phenomenon of simultaneous nitrification and denitrification in the aerobic reactor and phenomenon of denitrifying phosphorus removal in the anoxic reactor.?The settlement of activated sludge was good in SUFR-UCT system based on spiral up flow. The SVI was in the rage of 50~150mL/g. The plug-flow characteristics of spiral up flow within the reactor was easy to form granular sludge, the sludge particle size was in the rage of 0.7~0.9mm, MLVSS/MLSS was above 0.75. The average of SOUR was 31.8 mg/(g?h), the SNR was about 1.95mg/(g·h), the SPRR30 was26.82mg/(g·h), The ASPUR was 6.04mg/(g·h), The NSPUR was 4.27mg/(g·h), The activated sludge had a good ability to remove nitrogen and phosphorus. In addition, the sludge yield coefficient of SUFR-UCT system was about 0.60 which was 15% lower the traditional. There were rich activated sludge biological phases, of which the sessile ciliates were the major and still some swimming ciliates or rotifers, nematodes and other metazoans.?The organic removal had a greater impact resistance on the COD, C/N and C/P. The denitrification significantly reduced with persistent high COD. Influent C/N also had some impacts on the nitrogen removal. Higher SRT was conducive to the proliferation of nitrifying bacteria and the SND and nitrogen removal had been strengthened. But sludge aging serious and the nitrogen removal decreased when the SRT was more than 25 days. The phosphorus removal had a higher resistance to influent COD and C/N. When the influent C/P is low, the phosphorus removal rate was lower because it can not absorb the phosphorus in time. When the C/P was high, anaerobic phosphorus release and aerobic phosphorus uptake had declined because the lower influent P limited the normal life activities of microorganisms. In addition, phosphorus removal also had a certain impact resistance capacity on SRT.The removal of nitrogen and phosphorus returned to the level of before within a week after 72 hours'outage. According to the analysis, the unique structure and flow characteristics of spiral up-flow reactor were the root cause of the formation of granular sludge within the system.?After the isolation, purification, screening, selected and sequencing 16SrDNA, the two strains belonged Rhodococcus.sp and Gordonia.sp. The nitrogen removal rate of the two strains were 61.2% and 58.7% after four days'aerobic denitrification. In addition, the two strains had higher concentrations of oxygen tolerance and a wide range of temperature adaptation.?The phenomenon of denitrifying phosphorus uptake were studied, it was found that denitrifying phosphorus was not increased when increasing the anaerobic phosphorus release. by the amount of linear analog to the anaerobic phosphorus release and COD consumption obtained the conostant K?P /?COD was 0.21. In the case of excessive dosing nitrate did not bring anoxic phosphorus uptake rate and the P uptake increase significantly. The existence of COD in anoxic reactor is not conducive to denitrification but not to denotrifying phosphorus removal. In the same reaction time, the anoxic phosphorus uptake could not absorb all the P released in the anaerobic reactor, but the aerobic phosphorus could.?After the isolation, purification, screening, selected and sequencing 16SrDNA, the strain which had the best phosphorus uptake capacity belonged Bacillus.sp. The phosphorus removal rates of the four strains were 26.68%, 46.11%, 40.78% and 37.46% in 24 hours.?By means of the regression analysis, obtained the regression equations of TN removal rate, TP removal rate, nitrification rate, denitrifying rate, release phosphorus rate and P uptake rate. The regression equations were proved having good significant, fitting degree and accuracy. The analysis also got the optimal SRT, C/N and C/P as about 25d, 25 and 70 for TN removal rate, and the optimal SRT, C/N and C/P as 17d, 8, 80 for TP removal rate, and the optimal SRT, C/N and C/P respectively as 8d, 5 and 100 for nitration rate and release phosphorus P uptake rate, the optimal SRT, C/N and C/P respectively as 30d, 25, 100 for denitrifying rate. ?The material balan ce equation of SUFR-UCT system was established . The kinetics of nitrogen and phosphorus removal was got by calculating. Combined with experimental data on the sewage treatment, evaluate the kinetic models. The results showed that predicted and measured values were in good agreement which proved the kinetic models had good predictability.