三种载体上生物膜硝化作用动力学初步研究

通过测定水中COD、：NH4^ —N、NO2^-—N及NO3^-—N的浓度变化，研究了淹没式废水处理装置中沸石、活性炭和沙粒3种载体上硝化作用生物膜的动力学过程和反硝化作用。结果表明，3种载体上生物膜降解有机物(以COD表示)的过程可用一级动力学方程描述，反应速率常数分别为：沙粒0．0848h^-1、活性炭0．1187h^-1、沸石0．1334h^-1。3种载体上生物膜去除氨态氮的过程则可用零级动力学方程描述，反应速率常数分别为：沙粒-0．7743h^-1、活性炭-0．9886h^-1、沸石-1．0714h^-1．附着于沙上的生物膜去除亚硝酸盐氮的过程也可用零级动力学方程描述，反应速率常数为-0．6057h^-1，水中硝酸盐氮浓度较高时，载体沸石和活性炭上可能附着生长反硝化菌。图5表2参15。     

传统生物脱氮反硝化过程的生化机理及动力学

传统生物脱氮是指以硝酸盐为电子受体的一系列生物还原反应过程,该过程是在硝酸盐还原酶、亚硝酸盐还原酶、一氧化氮还原酶和一氧化二氮还原酶的作用下完成的.反硝化的生化机理及动力学是生物脱氮技术的理论基础.为促进反硝化生物脱氮技术的进一步发展,理解反硝化一系列复杂的生化反应过程及其电子传递、能量转化模式是十分必要而有意义的.本文通过对反硝化生化反应过程相关机理的论述,系统归纳了一个涉及多种酶及多种中间产物并伴随着电子(能量)传递的复杂反硝化生化反应过程,详细总结分析了反硝化过程电子通过电子传递链从电子供体(NADH)传递到终端电子受体的传递模式,以及借助于Peter提出的化学渗透假说建立的能量产生方式.同时建议采用积分法和微分法来确定反硝化动力参数Vmax,NO3,μDmax,KS,No3-.     

复合自养反硝化材料处理低碳氮比硝酸盐污水

作为一种典型的硝酸盐污水,低碳氮比硝酸盐污水的存在具有广泛性,且对生态环境和居民健康带来的危害日益突出.本研究构建了复合硫自养反硝化(CSAD)体系,基于硫-碳酸钙型复合材料与微生物,进行低碳氮比硝酸盐污水的深度处理,分析了材料投加量、粒径以及进水硝酸盐浓度对CSAD的影响,并探究了硝酸盐去除的动力学行为.结果 表明,...     

硫自养高氯酸盐还原菌和反硝化菌的培养和驯化

为了提高硫自养高氯酸盐和硝酸盐的还原效率,进行了以单质硫(S0)和好氧污泥分别作为电子供体和接种污泥培养驯化硫自养高氯酸盐还原菌和反硝化菌的过程研究.结果显示,在厌氧条件下采用间歇周期运行的培养方式,高氯酸盐和硝酸盐的初始浓度分别从80 mg/L和40 mg/L逐渐增加到240 mg/L和120 mg/L时,去除率达到99%以上的周期随培养驯化时间的增加而逐渐缩短,从最初的7 d稳定在4 d,高氯酸盐和硝酸盐最终分别被还原为Cl-和N2.由于S0的歧化反应,SO42-的实际产生量高于理论产生量.培养驯化过程中pH在6.5-7.3范围内变化,适合硫自养高氯酸盐还原菌和反硝化菌生长、发育和繁殖的条件.PCR-DGGE图谱分析表明随着培养和驯化时间的增加微生物种群数量逐渐减少,污泥微生物群落能够迅速进行优胜劣汰,达到适应环境的目的.培养驯化末期的污泥中β变形杆菌纲处于优势地位,是硫自养高氯酸盐还原菌和反硝化菌的主要组成部分.因此,经培养驯化的微生物菌群具有较高的高氯酸盐和硝酸盐还原能力,本研究可为水中高氯酸盐和硝酸盐净化技术提供一定的理论依据和技术支持.     

磁性壳聚糖凝胶微球固定反硝化菌去除地下水中硝酸盐氮

本研究从活性污泥中分离出氢自养反硝化细菌,在厌氧条件下利用氢气作为电子受体,将硝酸盐氮污染物彻底还原为氮气.通过原位共沉淀/柠檬酸钠交联法制备了一种磁性壳聚糖微球,将氢自养反硝化菌固定于磁性壳聚糖微球上组成固定化微生物反硝化体系.利用16SrDNA菌种鉴定、扫描电镜(SEM)、傅里叶红外光谱(FTIR)对固定化前后的材料进行了表征,并与游离的氢自养反硝化菌进行对比,同时进行静态批实验考察了在不同影响因素下硝酸盐去除效果.结果表明,分离出的氢自养反硝化菌属于陶厄氏菌属(MK928401),且被成功固定在磁性壳聚糖微球上;相同时间内,固定化氢自养反硝化菌对硝酸盐氮去除率高出游离细菌59%,说明固定化菌克服了由于游离菌易团聚而限制反硝化速率的缺点;磁性壳聚糖微球的加入,在一定程度上拓宽了氢自养反硝化菌对硝酸盐氮浓度的适应范围,同时拓宽了氢自养反硝化菌对pH的耐受范围;固定化氢自养反硝化菌经5次重复利用后,仍能高效还原硝酸盐氮,相比于游离细菌具有可回收和循环利用性.以上结果得出,以磁性壳聚糖微球固定氢自养反硝化菌,为高效去除地下水中的硝酸盐氮提供了一种更有效的途径.     

污水深度处理生物滤层中菌群的时空分布特征

以生物滤柱为反应器,对污水进行深度处理。试验表明,生物滤层中的菌群由于生化特性的不同,启动阶段异养菌要比自养菌的生长提前一周左右。生物滤柱异养菌、自养菌的形成对稳定运行非常关键,启动阶段较高的COD容积负荷不利于亚硝化、硝化细菌的产生。异养菌在竞争中占有优势,主要生长在滤柱的进水端和悬浮生物膜中。进水有机物浓度较低,造成亚硝化细菌的分布同异养菌分布基本一致。硝化细菌由于较弱的竞争能力,主要生长在滤柱的出水端和吸附生物膜中。底物浓度的改变使生物膜中的菌群对有机物、溶解氧以及生存空间的竞争也发生变化,最终导致其分布也随之改变。     

厌氧氨氧化电子受体的研究

研究发现，除已经证实的硝酸盐外，常规生物反硝化反应的两种中间产物亚硝酸和Ｎ２Ｏ也能用作氨厌氧氧化的电子受体；厌氧氨生物氧化的主要产物为Ｎ２．     

堆肥物以及堆肥物与铁屑联用原位修复硝酸盐污染地下水研究

针对地下水硝酸盐污染问题,借助柱实验开展堆肥物以及堆肥物与铁屑联用(以下简称堆肥物+铁屑)分别用于原位生物修复的动态模拟研究,考察生物反硝化的运行效果,探讨水化学参数的变化,分析硝酸盐的转化过程,确认地下水流速和进水硝酸盐浓度的影响,力求拓展纤维素类固体有机碳源的种类和提高纤维素固体有机碳源的反硝化速率。结果表明,堆肥物与堆肥物+铁屑引起的NO_3~-去除率分别为75.08%~79.57%和82.24%~86.48%。堆肥物用于原位生物反硝化可行且高效,而且堆肥物+铁屑通过氢自养反硝化更能增强NO_3~-的去除。堆肥物与堆肥物+铁屑引起的反硝化速率分别为9.69和11.30 g·m~(-3)·d~(-1),显著高于锯屑的反硝化速率(0.30g·m~(-3)·d~(-1))。25~100 d时,堆肥物引起的总有机碳(TOC)质量浓度增量始终≤18.34 mg·L~(-1)。在运行期间(0~100 d),堆肥物引起出水pH值始终低于进水值。堆肥物+铁屑引起TOC和pH值的变化展现出了与堆肥物相似的规律。运行10 d后,堆肥物以及堆肥物+铁屑将绝大部分NO_3~--N转化为气态氮。渗流速度和进水NO_3~-浓度显著影响堆肥物以及堆肥物+铁屑的生物反硝化效果。     

多孔钛板负载Pd-Cu催化还原水中硝酸盐氮的研究

研究了多孔钛板负载Pd-Cu(1:1)催化剂作为阴极,利用电化学反应器脱除水中的硝酸盐氮,在pH值为6.4,电极板的电流密度为2.3mA·cm-2的条件下,以0.1g·1-1无水硫酸钠作为支持电解质,反应4h后,硝酸盐氮的去除率可以达到36%,出水浓度已接近饮用水标准,然而在此催化剂负载比例下对副产物氨氮的选择率非常高.反应在300mA,pH值为6.4时脱硝效果最高.在合适的浓度下,NO3-占优势地位,受竞争吸附影响小,同时电极板吸附位未达到饱和时,电催化反硝化反应符合表观一级反应动力学.另外,溶液的传质对反硝化没有显著影响;进水口的外露形成的水流跌落有利于NH3的逸出,反应溶液中的NH4 -N副产物减少,但是硝酸盐氮的去除效果受到影响.     

不同进水有机物浓度下移动床生物膜反应器(SBMBBR)脱氮除磷特性

考察了不同进水有机物浓度下厌氧/好氧序批式移动床生物膜反应器（SBMBBR）污染物去除特性,实验结果表明,SBMBBR能够实现低碳源污水中氮和磷的同步去除,在进水TN和TP浓度分别为116.7 mg.L-1和11.5 mg.L-1、COD浓度为456 mg.L-1的条件下,TN和TP去除率分别达到94.3%和92.2%以上.反应器除磷是基于常规生物除磷和反硝化除磷过程实现的,脱氮主要是基于好氧段发生的同时硝化反硝化（SND）作用而完成.由于生物膜内部存在的DO扩散梯度,在好氧阶段混合液DO浓度不断提高的条件下反应器内具有良好SND反应的发生.进水COD浓度由149 mg.L-1提高至456 mg.L-1的过程中,反应器硝化效果不变,反硝化和除磷效果改善.反应器在好氧阶段pH值基本维持在7.0—7.1之间,为各类菌群的生长创造了条件.碱度变化较pH值更能反映硝化和反硝化反应发生的程度.反应器中微生物相丰富,生物膜以丝状菌为骨架,其上附着大量的球状菌和杆状菌,而悬浮活性污泥中丝状菌较少,形成了由细菌、真菌到原生动物和后生动物的复杂的生态体系,为系统取得稳定的污水处理效果提供了有效的保证.     

Effect of denitrifying bacteria on the electrochemical reaction of activated carbon fiber in electrochemical biofilm system

An electrochemical-activated denitrifying biofilm system consisting of activated carbon fiber electrodes immobilized with denitrifying bacteria film as cathode was studied. A revised model for an electrochemical-activated denitrifying biofilm was developed and validated by electrochemical analysis of cathodal polarization curves and nitrate consumption rate. The cathodal polarization curve and nitrate consumption rate were introduced to verify the rate of electrochemical reaction and the activity of denitrifying bacteria, respectively. It was shown that the denitrification process effectively strengthened the electrochemical reaction while the electron also intensified denitrification activity. Electron was transferred between electrochemical process and biological process not only by hydrogen molecule but also by new produced active hydrogen atom. Additionally, a parameter of apparent exchange current density was deprived from the cathodal polarization curve with high overpotential, and a new bio-effect current density was defined through statistical analysis, which was linearly dependent to the activity of denitrification bacteria. Activated carbon fiber (ACF) electrode was also found to be more suitable to the electrochemical denitrifying system compared with graphite and platinum.     

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.     

Bioreduction of nitrate in groundwater using a pilot-scale hydrogen-based membrane biofilm reactor

A long-term pilot-scale H₂-based membrane biofilm reactor (MBfR) was tested for removal of nitrate from actual groundwater. A key feature of this second-generation pilot MBfR is that it employed lower cost polyester hollow fibers and still achieved high loading rate. The steady-state maximum nitrate surface loading at which the effluent nitrate and nitrite concentrations were below the Maximum Contaminant Level (MCL) was at least 5.9 g·N·(m²·d)^?1, which corresponds to a maximum volumetric loading of at least 7.7 kg·N·(m³·d) ^?1. The steady-state maximum nitrate surface area loading was higher than the highest nitrate surface loading reported in the first-generation MBfRs using composite fibers (2.6 g·N·(m²·d)^?1). This work also evaluated the H₂-utilization efficiency in MBfR. The measured H₂ supply rate was only slightly higher than the stoichiometric H₂-utilization rate. Thus, H₂ utilization was controlled by diffusion and was close to 100% efficiency, as long as biofilm accumulated on the polyester-fiber surface and the fibers had no leaks.     

Improved nitrogen removal in dual-contaminated surface water by photocatalysis

River waters in China have dual contamination by nutrients and recalcitrant organic compounds. In principle, the organic compounds could be used to drive denitrification of nitrate, thus arresting eutrophication potential, if the recalcitrant organics could be made bioavailable. This study investigated the potential to make the recalcitrant organics bioavailable through photocatalysis. Batch denitrification tests in a biofilm reactor demonstrated that dual-contaminated river water was short of available electron donor, which resulted in low total nitrogen (TN) removal by denitrification. However, the denitrification rate was increased significantly by adding glucose or by making the organic matters of the river water more bioavailable through photocatalysis. Photocatalysis for 15 min increased the Chemical Oxygen Demand (COD) of the river water from 53 to 84 mg·L^-1 and led to a 4-fold increase in TN removal. The increase in TN removal gave the same effect as adding 92 mg·L^-1 of glucose. During the photocatalysis experiments, the COD increased because photocatalysis transformed organic molecules from those that are resistant to dichromate oxidation in the COD test to those that can be oxidized by dichromate. This phenomenon was verified by testing photocatalysis of pyridine added to the river water. These findings point to the potential for N removal via denitrification after photocatalysis, and they also suggest that the rivers in China may be far more polluted than indicated by COD assays.     

一株好氧反硝化细菌的鉴定及其在废水处理中的应用

从武汉市郊稻田土壤中分离得到一株好氧反硝化细菌HS-03,对其反硝化能力进行了研究.结果表明:细菌HS-03在好氧条件下能有效去除人工废水中的NO3-(10mmol/L),去除率达90%以上,并且在反应过程中没有NO2-的积累.菌株HS-03与Pseudomonasstutzeri的16SrDNA序列具有99.1%的相似性.对该菌株的16SrDNA序列以及生理生化特征分析表明,细菌HS-03是P.stutzeri的一个新分离种.实验采用ClastalW和PHYLIP程序对该菌株与报道菌进行了系统发育进化分析.图5表2参14     

Simultaneous nitrification and denitrification in activated sludge system under low oxygen concentration

Simultaneous nitrification and denitrification (SND), which is more economical compared with the traditional method for nitrogen removal, is studied in this paper. In order to find the suitable conditions of this process, a mixed flow activated sludge system under low oxygen concentration is investigated, and some key control parameters are examined for nitrogen removal from synthetic wastewater. The results show that SND is accessible when oxygen concentration is 0.3–0.8 mg/L. The nitrogen removal rate can be obtained up to 66.7% with solids retention time (SRT) of 45 d, C/N value of 10, and F/M ratio of 0.1 g COD/(g MLSS·d). Theoretical analysis indicates that SND is a physical phenomenon and governed by oxygen diffusion in flocs.     

Laboratory evaluation of kinetic parameters for lake sediment denitrification models

Laboratory experiments using the acetylene blockage technique showed that denitrification rates in sediments from Lake Okeechobee, Florida, are described by Michaelis-Menten nitrate dependence and Arrhenius temperature dependence (E_act = 15.5 kcal, but do not appear to be affected by seasonal differences in the supply of carbon substrates in this eutrophic lake. Peak nitrate concentrations in the sediments are in the range of the half-saturation constant, and thus, for a given temperature, k_d varies by a factor of approximately two over the typical range of nitrate concentrations. Most diagenetic sediment denitrification models employ a single-valued rate constant k_d, to describe nitrate dependence. However, the use of a constant k_d for eutrophic lake sediments may result in a significantly erroneous estimate of annual denitrification loss.     

应用在线传感器实现前置反硝化工艺生物脱氮的过程控制

为了实现前置反硝化工艺硝化反硝化反应的过程控制,系统地研究了硝化反硝化过程中DO、pH和ORP的变化规律,并考察了它们作为硝化反硝化过程控制参数的可行性.结果表明,pH值在缺氧区的变化分为下降型和上升型,从而指示系统反硝化反应进行的程度以及内循环回流量是否充足;缺氧区末端ORP值和硝酸氮浓度具有较好的相关性;好氧区第1格室的DO浓度可以指示进水氨氮负荷高低;pH值在好氧区的变化也可分为下降型和上升型,可指示系统硝化反应进行的程度、曝气量和碱度是否充足;好氧区末端ORP值与出水氨氮、硝酸氮浓度具有很好的相关性.在此基础上建立了硝化反硝化反应在线控制系统,从而实现曝气量、内循环回流量和外碳源投加量的在线控制,提高系统出水水质、降低运行费用.图7表1参8