【作者】 陆彩霞；

【导师】 顾平；

【作者基本信息】 天津大学 ， 环境工程， 2010， 博士

【摘要】 针对我国饮用水受硝酸盐污染严重、威胁人类健康的现状,提出采用氢自养反硝化技术去除饮用水中高浓度硝酸盐的解决方案。本文主要采用透气膜为氢气扩散器,重点考察了三种氢自养生物膜反应器——一体式透气膜-生物膜反应器(IGM-BR)、分体式透气膜-生物膜反应器(AGM-BR)和分体式生物膜反应器(A-BR)对饮用水中高浓度硝酸盐的去除效果,为氢自养反硝化技术在饮用水处理中的应用提供参考依据。采用双Mechaelis-Menten方程来描述氢自养反硝化的动力学过程,通过序批试验测定附着生长型反硝化系统的动力学参数,主要包括硝酸盐的饱和常数KN1、亚硝酸盐的饱和常数KN2以及氢气的饱和常数KH1和KH2,测定结果分别为KN1=2.09 mg/L,KN2=1.55 mg/L,KH1= 0.059 mg/L,KH2=0.006 mg/L。IGM-BR反硝化效果不好,出水硝酸盐和亚硝酸盐浓度均较高,硝酸盐和总氮的去除率分别低于60%和40%。硝酸盐还原速率(NRR)和总氮去除速率(TNRR)均较低,分别低于200 g/(m3·d)和150 g/(m3·d)。AGM-BR和A-BR的反硝化效果明显好于IGM-BR,主要表现在硝酸盐去除率高、出水浓度低,出水总氮基本上满足小于10 mg/L的要求。连续试验中,AGM-BR和A-BR的NRR可达300 g/(m3·d)以上,TNRR在250 g/(m3·d)左右。AGM-BR的NRR和TNRR最高值出现在序批试验中,分别为471.36 g/(m3·d)和443.52 g/(m3·d),表明反应器的反硝化能力仍有改善余地。硝酸盐负荷和溶解氢气(DH)浓度是影响反硝化效果的主要因素。三种反应器均存在反硝化不完全的问题,虽然出水总氮浓度能满足低于10 mg/L的要求,但是出水亚硝酸盐浓度超出标准要求很多。次氯酸钠可有效氧化亚硝酸盐为硝酸盐。实验结果表明,亚硝酸盐的氯氧化过程可用一级动力学方程来描述,反应速率受亚硝酸盐浓度和pH值的影响较大,计量关系与水相中有机物存在与否关系不大。经氢自养反硝化后,出水有机物浓度比进水有所增加,增加幅度受硝酸盐负荷影响。在低硝酸盐负荷下,反硝化菌缺少基质,发生自身水解,出水有机物浓度较高。在较高硝酸盐负荷下,出水有机物浓度较低,试验测定出水总有机碳(TOC)比进水通常高0.23-0.87 mg/L。铁混凝对出水有机物没有明显去除效果。由于受氢气压力、硝酸盐负荷、水温等多种因素的影响,IGM-BR出水水质波动很大,运行不稳定;与其相比,AGM-BR和A-BR运行较稳定。试验发现,填料堵塞是影响反应器长期运行稳定性的主要因素。总之,虽然氢自养反应器在应用过程中出现了不少问题,但是随着研究的深入,这些问题逐渐得以解决。同时,氢自养反硝化技术在饮用水中高浓度硝酸盐去除方面表现出一定的优势。相信随着技术的不断完善,氢自养反硝化技术在饮用水处理领域将具有广泛的应用前景。更多还原

【Abstract】 Nitrate contamination in drinking water becomes severe and presents a threat to human health. To solve this problem, hydrogenotrophic denitrification was employed to remove high concentration nitrate from drinking water. Gas-permeable membrane served as hydrogen diffuser in the denitrification process. Denitrification performance of three hydrogenotrophic biofilm reactors, integrated gas-permeable membrane biofilm reactor (IGM-BR), apart gas-permeable membrane biofilm reactor (AGM-BR) and apart biofilm reactor (A-BR), used to remove high concentration nitrate from drinking water, was investigated as a reference for wide practical application of hydrogenotrophic denitrification.A double Mechaelis-Menten form was employed to describe the hydrogenotrophic denitrification kinetics. Kinetic parameters, mainly the saturation constants of nitrate (KN1), nitrite (KN2) and hydrogen (KH1 and KH2), were measured by batch tests in an attached-growth denitrification system. The results showed that KN1 was 2.09 mg/L, KN2 was 1.55 mg/L, KH1 was 0.059 mg/L and KH2 was 0.006 mg/L.The denitrification performance of IGM-BR was not so good with high concentration nitrate and nitrite in the effluent. Lower than 60% of nitrate and 40% of total nitrogen were removed, respectively, and nitrate reducing rate (NRR) and total nitrogen removal rate (TNRR) were less than 200 g/(m3·d) and 150 g/(m3·d), respectively. AGM-BR and A-BR performed better than IGM-BR in the term of good nitrate removal and less nitrate in the effluent. The effluent total nitrogen was below 10 mg/L, satisfying the requirement of this study. In the continuous experiments, NRRs of AGM-BR and A-BR could achieve above 300 g/(m3·d), and TNRRs were about 250 g/(m3·d). The maximum NRR and TNRR of AGM-BR appeared in batch test, 471.36 g/(m3·d) and 443.52 g/(m3·d), respectively, indicating that improvement of denitrification capacity was available for the reactor. Nitrate loading and dissolved hydrogen (DH) concentration were the main factors influencing denitrification performance.Incomplete denitrification occurred in all of the three reactors. Although the effluent total nitrogen was less than 10 mg/L, the effluent nitrite concentration was more than the standards required. Nitrite could be oxidized to nitrate by sodium hypochlorite. The tests results showed that the kinetics of nitrite oxidation by hypochlorite followed the first-order form. The reaction rate was influenced by nitrite concentration and pH value, and the stoichiometric relationship between nitrite and hypochlorite was unrelated with the organics in the water.The organics in the effluent increased after hydrogenotrophic denitrification treatment, and the increasing amount depended on the nitrate loading of the reactor. Under low nitrate loading, denitrifying bacteria lacked substrates and self-hydrolysis occurred. Thus, the organics concentration in the effluent was relatively high. Under high nitrate loading, the organics in the effluent was low, and the measured total organic carbon (TOC) was 0.23-0.87 mg/L higher than that in the influent Coagulation with ferrous-coagulant had no obvious effect on organics removal.Under the influence of many factors, such as hydrogen pressure, nitrate loading and temperature, the effluent water quality of IGM-BR fluctuated and IGM-BR was in an unstable running state. Compared with that, AGM-BR and A-BR worked stably. It was found that clogging was the main factor influencing the stability of the reactor for long time operation.In conclusion, although some problems had arisen during the application of hydrogenotrophic reactors, they were resolved gradually as the investigation went on. Moreover, hydrogenotrophic denitrification exhibited some advantages for the removal of high concentration nitrate from drinking water. It is believed that hydrogenotrophic denitrification will have an extensive future in the field of drinking water treatment as it is improved.更多还原