Under The Condition Of Different Substrates Asbr Reactor Performance Test Research

The nitrogen pollution of the wastewater has gone from bad to worse, it breaks up the ecology balance and threatens drinking water safety. Biological wastewater nitrogen removal is the focus of water pollution control. Anaerobic ammonium oxidation (ANAMMOX) shows board development and application prospect because of high-efficiency and energy-saving. But anaerobic ammonium oxidation bacterial is slow-growing; the reactor start-up time is long; the operation of reactor is not stable; ANAMMOX is vulnerable to environmental factors. These reasons limit the application of ANAMMOX technology. Starting up of ANAMMOX and effect of substrate concentration, pH to nitrogen removal performance were studied in an anaerobic sequencing batch reactor (ASBR) treating the municipal sewage.Inoculated with nitrifying sludge, the anaerobic ammonium oxidation was started up successfully for130d in an anaerobic sequencing batch reactor. The experimental conditions were as follows:temperature (35±1)℃,HRT24h and pH7.3-8.5. Experimental results indicated that when the average volumetric load of total nitrogen was0.179kg/(m3-d),the average removal rates of NH4+-N, NO2--N and TN were95.30%,91.30%and76.28%at stable stage. The ratio of ammonium removal, nitrite removal and nitrate increase was1:1.54:0.25at start-up stage, and it was1:1.27:0.27at stable stage. The pH increment between influent and effluent changed from0.85at start-up stage to0.24at stable stage. Denitrification and ANAMMOX were existed simultaneously at start-up stage, however, ANAMMOX became the dominant reaction at stable stage. MLSS and MLVSS/MLSS decreased at the beginning and then increased. The changing process reflected the decease of nitrobacteria, denitrifying bacteria and the enrichment of ANAMMOX bacteria. This was in concert with nitrogen removal performance.Ammonia nitrogen and trite nitrogen are substrate of ANAMMOX, and they are also inhibitory substance. Effect of NH4+and NO2-to nitrogen removal performance was studied in an ASBR by increasing substrate concentration. Experimental results indicated that influent NO2-concentration had a significant effect to ANAMMOX. Total nitrogen (TN) removal efficiency decreased to below60%when influent NO2-concentration was increased to210mg/L. Performance of ASBR was changed when influent NO2-concentration was increased to235mg/L(free nitrous acid, FNA concentration was0.013mg/L):the nitrate nitrogen removal rate fell sharply to72%, TN removal rate dropped to46%. Influent NH4+/NO2-ratio also had a significant effect to ANAMMOX, the appropriate range was1.07-1.43. The operation of ASBR was stable when influent NH4+/NO2-ratio was1.07-1.43. NH4+, NO2-,TN removal rate maintained more than80%,90%,60%separately. NH4+,NO2-,TN removal rate dropped to81.41%,63.49%,46.48%separately when NH4+/NO2-ratio increased to1.67.The effect of influent ammonia nitrogen to nitrogen removal performance was not significant and it was lower than trite nitrogen. NO2-removal rate were more than96%, NH4+, TN removal rate maintained higher than50%when influent ammonia nitrogen concentration was blow700mg/L. When influent NH4+concentration increased to800mg/L(free ammonia, FA concentration was27.86), NH4+,NO2-,TN removal rate dropped to48.27%,91.38%,47.07%respectively, nitrogen removal performance of ASBR deteriorated.Kinetic characteristics for ammonia nitrogen and trite nitrogen inhibit was studied. The substance inhibitory could be described by the Haldane model. The half saturate coefficient and inhibition coefficient of NH4+were123.99mg/L and853.32mg/L. The half saturate coefficient and inhibition coefficient of NO2-were9.02and202.17mg/L respectively.The effect of pH to ANAMMOX was studied by setting influent pH at6.5,7.0,7.5,8.0,8.5. Experimental results indicated that different influent pH had a significant effect to ANAMMOX. The nitrogen removal performance was inhibited when influent pH was6.5and8.5. NH4+,NO2-TN removal rate were73.71%,61.67%,47.19%at pH6.5and they were83.35%,88.10%,63.64%when pH was8.5. Low pH had more significant effect to ANAMMOX. The ANAMMOX bacterial was more suit to alkaline environment. The appropriate pH was7.0-8.0. NH4+,NO2-,TN removal rate maintained more than93%,92%and71%when influent pH was7.0-8.0. The nitrogen removal performance was best when influent pH was7.5.When influent pH was6.5, the aerobic nitrification reaction and the ANAMMOX reaction occurred in the beginning and then the ANAMMOX reaction, denitrification reaction occurred. The ANAMMOX reaction were the dominant reaction and feeble denitrification reaction was also existed when pH was7.5. When influent pH was8.5, the denitrification reaction and the ANAMMOX reaction occurred in the beginning and then the ANAMMOX reaction was principal reaction with poor denitrification reaction.The most appropriate pH was7.5996by studied kinetic characteristics for pH effect to ANAMMOX. This was in concert with determined result.