短程硝化的生化机理及其动力学

短程硝化的生化反应机理和动力学是生物脱氮技术的理论基础,同时也是生物脱氮工艺设计、运行科学化和合理化的重要依据.基于短程硝化的生化机理、氨氧化菌的电子传递(能量产生)模式,从微生物学和化学计量学两个方面详细论述了短程硝化一系列复杂的生化反应过程.由此可知,短程硝化是一个涉及多种酶及多种中间产物,并伴随着电子(能量)传递的复杂生化反应过程,是基质(NH4 -N)利用(产能代谢)和微生物(氨氧化菌)增殖(合成代谢)两类反应的综合,因此,研究氨氮比利用速率和氨氧化菌比增殖速率动力学则是对短程硝化反应的深层次研讨.并建议采用积分法和微分法来确定动力学参数μnmax、KN、vnmax.     

Metagenomic insights into responses of microbial population and key functional genes to fulvic acid during partial nitritation

The long-term impact of fulvic acid (FA) on partial nitritation (PN) system was initially examined in this study. The obtained results revealed that the FA lower than 50 mg/L had negligible effect on the nitrite accumulation rate (NAR nearly 100%) and ammonium removal rate (ARR 56.85%), while FA over 50 mg/L decreased ARR from 56.85% to 0.7%. Sludge characteristics analysis found that appropriate FA (<50 mg/L) exposure promoted the settling performance and granulation of PN sludge by removing Bacteroidetes and accumulating Chloroflexi. The analysis of metagenomics suggested that the presence of limited FA (0-50 mg/L) stimulated the generation of NADH, which favors the denitrification and nitrite reduction. The negative impact of FA on the PN system could be divided into two stages. Initially, limited FA (50-120 mg/L) was decomposed by Anaerolineae to stimulate the growth and propagation of heterotrophic bacteria (Thauera). Increasing heterotrophs competed with AOB (Nitrosomonas) for dissolved oxygen, causing AOB to be eliminated and ARR to declined. Subsequently, when FA dosage was over 120 mg/L, Anaerolineae were inhibited and heterotrophic bacteria reduced, resulting in the abundance of AOB recovered. Nevertheless, the ammonium transformation pathway was suppressed because genes amoABC and hao were obviously reduced, leading to the deterioration of reactor performance. Overall, these results provide theoretical guidance for the practical application of PN for the treatment of FA-containing sewage.     

活性污泥法的多变量最优控制Ⅲ.限制最高和同时限制平均与最高出水BOD浓度

在前文的基础上，进一步研究了更常用的限制最高和同时限制平均与最高出水有机物浓度两种排放标准的约束条件下，使其运行费用最省的最优周期控制问题。计算结果都表明，最优控制变量ＱＷ和ＤＯ的变化规律都尽可能使其满足的约束条件和节省运行费用，但是，当进水负荷变化幅度非常大时，任何控制也难于使出水水质达标，而运行费用还会大幅度增大。     

A2/O工艺强化反硝化除磷体系中微生物特性分析

为了更直观地认识反硝化除磷体系中生物脱氮除磷机理及运行状态,本文尝试了对A2/O工艺强化反硝化除磷体系在稳定运行期的活性污泥采取直接染色的手段,观察聚-β羟基丁酸(PHB)和聚磷酸盐(Poly-P)的沿程变化状况,同时结合活性污泥的电镜扫描图像,考察该系统的微生物菌群特征.试验结果表明,在厌氧阶段,微生物细胞内PHB的量大幅提高,上清液中磷酸盐的含量上升,聚磷酸盐含量明显下降,粒径为1~1.5μm、呈球状和棒状的菌群构成的葡萄状细胞簇占居优势;在缺氧阶段,微生物细胞内PHB的量下降,上清液中磷酸盐含量下降,聚磷酸盐含量上升,粒径为0.5~1μm的椭球菌与1.0~1.5μm的球杆菌占优势;在好氧阶段,微生物细胞内PHB的量较低或接近零,上清液中磷酸盐的含量接近零,聚磷酸盐含量明显上升,此时粒径1.0~1.5μm的球菌以单个或成对出现,球菌不再饱满,呈现接近消失的状态.相比之下,单纯的脱氮系统则不存在上述微生物特性的变化.图8参12     

活性污泥法的多变量最优控制Ⅱ.限制有机物(BOD)的排放总量

着重研究了有限制有机物排放总量时，使其运行费用最低的最优周期控制问题。通过增加新的状态变量和用补偿函数法，将本课题的有约束条件问题化为无约束条件问题，并提出了最优长参数的动态搜索法来修改传统的梯度法，从而较完善地解决了多变量最优周期控制的计算问题。     

Factors affecting simultaneous nitrification and denitrification in an SBBR treating domestic wastewater

An aerobic sequencing batch biofilm reactor (SBBR) packed with Bauer rings was used to treat real domestic wastewater for simultaneous nitrification and denitrification. The SBBR is advantageous for creating an anoxic condition, and the biofilm can absorb and store carbon for good nitrification and denitrification. An average concentration of oxygen ranging from 0.8 to 4.0 mg/L was proved very efficient for nitrification and denitrification. Volumetric loads of TN dropped dramatically and effluent TN concentration increased quickly when the concentration of average dissolved oxygen was more than 4.0 mg/L. The efficiency of simultaneous nitrification and denitrification (SND) increased with increasing thickness of the biofilm. The influent concentration hardly affected the TN removal efficiency, but the effluent TN increased with increasing influent concentration. It is suggested that a subsequence for denitrification be added or influent amount be decreased to meet effluent quality requirements. At optimum operating parameters, the TN removal efficiency of 74%–82% could be achieved. Translated from Acta Scientiae Circumstantiae, 2006, 26(5): 728–733 [译自: 环境科学学报]     

强化A2/O工艺反硝化除磷性能的运行控制策略

以啤酒废水为研究对象,重点考察了如何强化A2/O工艺反硝化除磷性能,从而提高营养物去除效果、并实现节能的目的.试验中建立了3种运行控制策略:(1)根据缺氧区末端出水硝酸盐的浓度控制内循环回流量;(2)调节厌氧/缺氧/好氧区体积比以减少厌氧区出水剩余COD对缺氧磷吸收的影响;(3)向缺氧区引入旁流并调节旁流比.试验结果表明,当缺氧区末端出水硝酸盐浓度控制在1～3 mg·L-1时,不仅可强化反硝化除磷效果,而且可以节省内循环所需能耗;厌氧/缺氧/好氧区最佳体积比为1/1/2;旁流的引入可以提高低C/N比条件下TN的去除,最优旁流比为0.32.     

城市污水处理厂Candidatus Accumulibacter的菌群结构及定量分析

Candidatus Accumulibacter是污水生物除磷系统中的优势聚磷菌.本研究采用编码聚合磷酸盐激酶的功能基因(polyphosphate kinase 1gene,ppk1)作为遗传标记,对9个污水处理厂共12个活性污泥样品中Accumulibacter的进化枝水平的丰度及其菌群结构进行了研究.实时定量PCR(Quantitative PCR,QPCR)的结果显示,Accumulibacter的6个进化枝(IA、IIA、IIB、IIC、IID、IIF)均存在于12个污泥样品中.A2O及其改良工艺中总Accumulibacter丰度最高,达到总菌的22.77%.所有样品中Accumulibacter均以Type-II为主,其中,IIC、IID的丰度均达到了108cells·g-1(以MLSS计),占Accumulibacter的平均比例分别为75.34%和14.87%,是污水处理厂中的优势聚磷菌.分支IA丰度最低,占总Accumulibacter比例平均只有0.32%.系统发育分析结果显示,每个样品中Accumulibacter分支多样化,均含有IIA、IIC、IID分支.QPCR和系统发育分析都证实了生物除磷效果与Accumulibacter的群落结构密切相关,除磷效果不好可能和IID占总Accumulibacter比例较高有关.     

厌氧氨氧化菌与其他细菌之间的协同竞争关系

随着污水脱氮行业的蓬勃发展,各种新工艺、新理论层出不穷.厌氧氨氧化(Anammox)工艺以其独特的优点脱颖而出,成为最具应用前景的新工艺.厌氧氨氧化菌作为该过程的执行者目前已发现5属17种,本文主要对5属17种的厌氧氨氧化菌进行总结,并对厌氧氨氧化菌种内关系中的群体感应系统进行详细介绍,此外还介绍了厌氧氨氧化菌与硝化菌、反硝化菌以及厌氧甲烷氧化菌之间的协同与竞争关系.最后给出常见竞争因素对厌氧氨氧化种群结构的影响,通过控制竞争因素来实现对厌氧氨氧化种群结构的调节.本文将厌氧氨氧化菌微生物生态学与厌氧氨氧化污水处理工艺相结合,为厌氧氨氧化工艺在污水生物处理中的应用提供理论依据.     

独立分格推流式活性污泥法的动力学分析

在严格控制试验条件的基础上,对独立分格式活性污泥法进行了定量的试验研究与动力学分析.结果表明,底物比降解速率常数K值并不是常数,而是随着易降解底物的降解去除逐渐变小;据此修正了该系统的传统动力学公式及相应的设计计算方法;给出了工艺设计时曝气池分格数的划分及其容积确定的基本原则.