低温域湿地植物根际硝化强度及氨氧化微生物研究

以低温域(0~15 ℃)下黄菖蒲(Iris pseudacorus)、菖蒲(Acorus calamus)和香蒲(Typha orientalis)3种湿地植物为研究对象,分别取其根际土壤测定硝化强度,并采用FISH(荧光原位杂交)技术,考察植物根际AOB(氨氧化细菌)、AOA(氨氧化古菌)的数量变化规律. 结果表明:低温条件下,香蒲根际土壤的硝化强度最高,平均值为1.40 mg/(kg·h),黄菖蒲和菖蒲的平均值均为0.96 mg/(kg·h). 湿地植物根际土壤中的细菌数量(数量级为1010)远高于古菌(数量级为108),其中AOB为优势菌种,3种湿地植物的AOA数量分别约占总古菌数量的46.0%、47.9%和49.7%. 3种湿地植物根际AOB的数量(以湿土计,下同)排序为香蒲(2.57×109 g-1)>黄菖蒲(1.23×109 g-1)≈菖蒲(1.14×109 g-1),AOA的数量(以湿土计)排序为黄菖蒲(2.78×108 g-1)>香蒲(2.57×108 g-1)>菖蒲(1.15×108 g-1). 微生物分布特性和硝化作用效果均表明,不同植物根际氨氧化过程的主要作用微生物具有一定差异,AOA和AOB对于湿地土壤氮转化均具有不可忽视的作用,并与植物本体、土壤硝化过程微环境之间有一定的耦合关系.      

N2O emission from a sequencing batch reactor for biological N and P removal from wastewater

Nitrous oxide （N2O） is a greenhouse gas that can be released during biological nitrogen removal from wastewater. N2O emission from a sequencing batch reactor （SBR） for biological nitrogen and phosphorus removal from wastewater was investigated, and the aims were to examine which process, nitrification or denitrification, would contribute more to N2Oemission and to study the effects of heterotrophic activities on N2O emission during nitrification. The results showed that N2O emission was mainly attributed to nitrification rather than to denitrification. N2O emission during denitrification mainly occurred with stored organic carbon as the electron donor. During nitrification, NaO emission was increased with increasing initial ammonium or nitrite concentrations. The ratio of N2O emission to the removed ammonium nitrogen （N2O- N/NH4-N） was 2.5% in the SBR system with high heterotrophic activities, while this ratio was in the range from 0.14% to 1.06% in batch nitrification experiments with limited heterotrophic activities.     

曝气生物滤池中总有机碳及氨氮的变化和对硝化作用的影响

采用以页岩陶粒为载体的曝气生物滤池(BAF)为反应器,研究了BAF运行中总有机碳和NH4 -N浓度沿滤层变化的规律,以及对硝化作用的影响.结果显示,在进行污水深度处理时,在BAF前段TOC的去除率占滤池总去除率的72.3%～100%;NH4 -N的去除率占滤池总去除率的91.8%～100%.碳化与硝化作用并存于BAF中,硝化作用随滤层加深而加强.水质和BAF滤料的结构特点是影响碳化与硝化作用的主要因素.     

生物沸石床污水脱氮效果及机理

研究了生物沸石床对模拟村镇生活污水中各形态氮及COD等污染物的去除效果结果表明,生物沸石床对NH₃^--N去除效果明显且稳定,去除率大于95%,对NO₃^--N的去除则受水力停留时间的影响较大从机理分析,生物沸石对NH₃-N的去除主要依靠化学吸附、离子交换以及生物硝化的协同作用,而对NO₃^--N的去除主要依赖反硝化作用.生物沸石的硝化作用明显,并受溶解氧浓度限制,沸石床中部沸石硝化强度只有表层沸石的1/2;其反硝化能力则随实验条件中C/N的不同而变化明显,当COD/TN=5时,反硝化作用最强,在时间变化规律上,前6h反硝化速率最大.     

胶体态有机物对生物膜硝化过程的影响

利用曝气生物滤池研究了胶体态和溶解态有机物对生物膜中硝化过程的影响.实验结果表明,胶体态有机物的水解过程进行得较为迅速,不会成为生物降解的限制过程.70%有机物的氧化在滤池的进口40cm内完成,而随着进水有机物浓度的增加硝化过程向滤池的上部迁移.胶体态有机物对硝化过程的抑制作用比同样浓度溶解态有机物略大.     

Nitrifying population dynamics in a redox stratified membrane biofilm reactor (RSMBR) for treating ammonium-rich wastewater

Nitrogen removal performance and nitrifying population dynamics were investigated in a redox stratified membrane biofilm reactor (RSMBR) under oxygen limited condition to treat ammonium-rich wastewater. When the NH4+-N loading rate increased from 11.1±1.0 to 37.2±3.2 gNH4+-N·m-2·d-1, the nitrogen removal in the RSMBR system increased from 18.0±9.6 mgN·d^-1 to 128.9±61.7 mgN·d^-1. Shortcut nitrogen removal was achieved with nitrite accumulation of about 22.3±5.3 mgNO2--N·L-1. Confocal micrographs showed the stratified distributions of nitrifiers and denitrifiers in the membrane aerated biofilms (MABs) at day 120, i.e., ammonia and nitrite oxidizing bacteria (AOB and NOB) were dominant in the region adjacent to the membrane, while heterotrophic bacteria propagated at the top of the biofilm. Real-time qPCR results showed that the abundance of amoA gene was two orders of magnitude higher than the abundance of nxrA gene in the MABs. However, the nxrA gene was always detected during the operation time, which indicates the difficulty of complete washout of NOB in MABs. The growth of heterotrophic bacteria compromised the dominance of nitrifiers in biofilm communities, but it enhanced the denitrification performance of the RSMBR system. Applying a high ammonia loading together with oxygen limitation was found to be an effective way to start nitrite accumulation in MABs, but other approaches were needed to sustain or improve the extent of nitritation in nitrogen conversion in MABs.     

Electromigration techniques as a modern tool to control the work of sewage treatment plant

In the present work, the possibility of using isotachophoresis (ITP) as an alternative method for the continuous control of sewage treatment plant efficiency is presented. The performed experiments focused on the nitrification process products as well as the determination of heavy metal concentration in raw sewage. Total concentration of nitrates and heavy metals is analysed in the sewage samples, ranging from 50 to 120mg/L and 0 to 1.9mg/L, respectively. The analytical error (below 10%), the analysis time (shorter then 50 minutes for heavy metals, and 12 minutes for nitrates) and the general analytical performance are better from those obtained by atomic absorption spectrometry (AAS) and ion selective electrode (ISE).     

潮汐-复合流人工湿地系统优化及对抗生素抗性基因的去除效果

抗生素抗性基因随废水排放传播扩散,对环境生物和民众健康构成严重威胁.针对废水中抗性基因的深度去除值得重点关注.在前期研究中发现潮汐流人工湿地能有效去除废水中多种氮素.本研究通过增加隔板和种植植物等方式进一步优化潮汐流人工湿地系统,并考察了工艺优化对抗性基因去除和脱氮功能微生物的影响机制.结果表明,同时增加隔板和种植植物后的潮汐-复合流人工湿地系统能有效提高抗性基因的去除效率,在增加隔板和种植植物组对7类21种抗性基因去除率最高达到83.82%~100.0%,显著高于单一增加隔板或种植植物组.从湿地基质和植物中的抗性基因绝对丰度对比可以看出,增加隔板能促进湿地基质中抗性基因量积累,而植物对抗性基因吸附也是其去除途径之一.同时,结合氮循环功能基因测序结果显示,湿地系统优化能提高基质中硝化和反硝化功能微生物物种多样性和丰富度,这与优化系统对废水中硝化量、反硝化量和总氮的去除率相对更高结果一致.     

低温驯化对自养脱氮颗粒污泥功能活性与菌群结构的影响分析

低温驯化是提高部分亚硝化-厌氧氨氧化（PN/A）组合工艺低温脱氮效能和运行稳定性的有效方法.为探究低温驯化对污泥特性的具体影响,本文从温度敏感性、颗粒外观形态、胞外聚合物（EPS）组成和微生物群落结构等方面,对中高温培养（30℃）和低温驯化（15℃）PN/A颗粒污泥之间的差异性进行了分析.反应热力学的研究结果表明,驯化污泥（G_L）在低温区（10~20℃）的脱氮性能较中高温培养污泥（G_H）有了显著提高,总无机氮去除的表观反应活化能（E_a）降低了28.4%.与G_H相比,G_L的平均粒径减小了25.8%,EPS含量增长了16.6%,颗粒的沉降性能明显下降.由高通量测序结果可知,G_L具有更高的菌群多样性,同时,污泥中好氧氨氧化菌（Nitrosomonas）与厌氧氨氧化菌（Candidatus_Kuenenia）的丰度比值（0.04）远小于G_H的0.34.这意味着颗粒污泥在低温环境中对慢速生长自养菌仍具有较强的截留能力.上述发现为解析PN/A污泥在低温条件下的自适应机制,推动组合工艺的工程化应用提供了重要参考.     

理化因素对脱氮硫杆菌自养反硝化的影响

从连续运行的UASB反应器厌氧污泥中分离得到一株脱氮硫杆菌T.d.a,采用分批摇床试验,采用脱氮硫杆菌标准培养基,以硫代硫酸钠为硫源,研究pH值、温度、氮源(NO3--N,NH4+-N)、能源(S2O32-)、碳源(HCO3-)、葡萄糖、无机盐(P, Mg2+, Fe2+)对该菌株自养反硝化的影响.结果表明,在pH6.5~8.0,温度20~35℃的范围内,T.d.a对NO3--N均有较高的去除速率,其最佳反硝化pH值为7.04,温度为27.40℃.T.d.a对554mg/L的NO3--N对T.d.a有一定的抑制作用;T.d.a反硝化所需NH4+-N的限制浓度为2.62mg/L;S2O32-浓度对T.d.a反硝化的影响主要取决于其与NO3-的比例关系,在NO3-过量的情况下,NO3--N去除率与加入的S2O32-量成近似的正比关系.T.d.a以HCO3-作为无机碳源时其限制浓度为29.05mg/L;0~2000mg/L的葡萄糖对NO3--N去除率没有明显影响.P和Mg2+的限制浓度分别为0.034,0.059mg/L,Fe2+的限制浓度低于0.058mg/L.