不同基质条件下ASBR反应器性能的试验研究

【作者】 李宁宁；

【导师】 于德爽；

【作者基本信息】 青岛大学 ， 环境工程， 2012， 硕士

【摘要】 水体的氮素污染日益严重,对水生态环境和饮水安全造成极大的危害,废水生物脱氮是水体污染控制领域的研究重点。厌氧氨氧化(anaerobic ammonium oxidation,简称ANAMMOX)生物脱氮工艺由于具有节能高效的显著优点,在废水生物脱氮领域中显示出广阔的开发和应用前景。但厌氧氨氧化菌生长缓慢,反应器启动时间长,且运行不稳定,容易受环境因素的影响等原因限制了该工艺的实践应用。为此,本文采用厌氧序批式反应器(anaerobic sequencing batch reactor,简称ASBR)在城市污水条件下进行厌氧氨氧化的启动与不同进水基质浓度、pH对反应器脱氮性能影响的研究。试验接种好氧硝化污泥,在温度为(35±1)℃、HRT为24h、pH为7.3-8.5的条件下经过130d的培养,成功启动了厌氧氨氧化反应,获得了砖红色的厌氧氨氧化污泥,电子显微镜扫描可观察到典型的厌氧氨氧化菌。试验结果表明：厌氧氨氧化反应稳定运行时,TN容积负荷平均为0.179kg/(m3·d), NH4+-N、NO2--N、TN去除率分别达到了95.30%、91.30%、76.28%。启动期和稳定运行期NH4+-N、NO2--N去除量和NO3--N生成量的比值分别达到1：1.54：0.25和1：1.27：0.27；稳定运行期进出水pH差值由启动时的0.85下降到0.24。启动期反硝化和厌氧氨氧化反应同时存在而在稳定运行期厌氧氨氧化发展成为主导反应。MLSS和MLVSS/MLSS先减少后增加,反映了启动过程中硝化细菌、反硝化细菌的衰亡和厌氧氨氧化菌逐渐富集的过程,这与反应器的脱氮效果越来越好相一致。氨氮和亚硝态氮既是厌氧氨氧化菌的反应基质,也是毒性抑制物质。通过提高进水基质浓度,分别研究了氨氮和亚硝态氮浓度对ASBR厌氧氨氧化反应器脱氮性能的影响。结果表明,进水亚硝态氮浓度对厌氧氨氧化有明显的影响,当进水亚硝态氮浓度达到210mg/L左右时,总氮去除效果受到影响,总氮去除率下降到60%以下；当进水亚硝态氮浓度达到235mg/L(即进水游离亚硝酸盐,FNA浓度为0.013mg/L)时,ASBR反应器性能发生改变,亚硝态氮去除率急剧下降到72%左右,总氮的去除率下降到46%左右。进水NO2-/NH4+比值对反应器的运行性能也有显著影响,进水NO2-/NH4+比值适宜范围为1.07-1.43。进水NO2-/NH4+比值在此范围内时,氨氮去除率维持在80%以上,亚硝态氮去除率维持在90%以上,总氮的去除率维持在60%以上,反应器运行稳定。当进水NO2-/NH4+比值升高到1.67时,氨氮、亚硝氮、总氮去除率均有下降,分别为81.41%、63.49%、46.48%,反应器显现典型的功能障碍。进水氨氮浓度对反应器脱氮效果的影响不显著,明显低于进水亚硝态氮浓度的影响。进水氨氮浓度在700mg/L以内时,亚硝态氮去除率保持在96%以上,氨氮和总氮去除率稳定在50%以上；进水氨氮浓度升高到800mg/L(即进水游离氨浓度,FA为27.86mg/L)时,氨氮、亚硝态氮、总氮去除率分别降低降低到48.27%、91.38%和47.07%,反应器脱氮性能恶化。对进水氨氮和亚硝态氮浓度抑制进行了动力学研究,Haldane模型可以很好的拟合氨氮和亚硝态氮浓度对厌氧氨氧化工艺性能的抑制作用,得出利用氨氮的半速率常数为123.99mg/L,氨氮抑制常数为853.32mg/L,亚硝态氮的半速率常数为9.02mg/L,亚硝态氮抑制常数为202.17mg/L,与实验测定值基本相符。将进水pH设定为6.5,7.0,7.5,8.0,8.5研究了pH对厌氧氨氧化的影响。结果表明,进水pH值对ASBR反应器的脱氮性能有显著影响。进水pH值6.5和8.5时,对ASBR厌氧氨氧化反应器的脱氮性能产生抑制作用,pH6.5时氨氮、亚硝态氮、总氮的去除率分别为73.71%、61.67%、47.19%,pH8.5时,氨氮、亚硝态氮、总氮的去除率分别为83.35%、88.10%、63.64%,低pH对厌氧氨氧化的抑制作用更加强烈,厌氧氨氧化菌更适宜于在碱性环境中生长。ASBR厌氧氨氧化反应器的适宜pH范围为7.0-8.0,在此范围内氨氮、亚硝态氮、总氮的去除率维持在93%、92%和71%以上,进水pH为7.5时反应器脱氮性能最好。通过对ASBR单周期内氨氮、亚硝态氮、硝态氮浓度变化的分析,得知pH6.5时,整个反应周期内先发生硝化反应和厌氧氨氧化反应,然后是厌氧氨氧化反应和反硝化反应。pH7.5时,厌氧氨氧化反应占绝对主导反应,同时存在微弱的反硝化反应。pH8.5时,先发生了反硝化反应和厌氧氨氧化反应,其后以厌氧氨氧化反应为主,仍伴有微弱的反硝化反应。通过研究pH对ASBR反应器厌氧氨氧化影响的动力学特性,得出最适pH值为7.5996,与实际测定pH7.5时反应器脱氮效果最好的结果相符。更多还原

【Abstract】 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.更多还原