Combined biologic aerated filter and sulfur/ceramisite autotrophic denitrification for advanced wastewater nitrogen removal at low temperatures

An innovative advanced wastewater treatment process combining biologic aerated filter （BAF） and sulfur/ ceramisite-based autotrophic denitrification （SCAD） for reliable removal of nitrogen was proposed in this paper. In SCAD reactor, ceramisite was used as filter and Ca （HCO3）2 was used for supplying alkalinity and carbon source. The BAF-SCAD was used to treat the secondary treatment effluent. The performance of this process was investigated, and the impact of temperature on nitrogen removal was studied. Results showed that the combined system was effective in nitrogen removal even at low temperatures （8℃）. Removal of total nitrogen （TN）, NH4＋ -N, NO3-N reached above 90% at room temperature. Nitrification was affected by the temperature and nitrification at low temperature （8℃） was a limiting factor for TN removal. However, denitrification was not impacted by the temperature and the removal of NO3 -N maintained 98% during the experimental period. The reason of effective denitrification at low temperature might be the use of easily dissolved Ca（HCO3）2 and high-flux ceramisite, which solved the problem of low mass transfer efficiency at low temperatures. Besides, vast surface area of sulfur with diameter of 2-6 mm enhanced the rate of microbial utilization. The removal of nitrate companied with the production of SO42-, and the average concentration of SO27 was about 240mg.L^-1. These findings would be beneficial for the application of this process to nitrogen removal especially in the winter and cold regions.     

沣河水系脱氮微生物群落结构研究

河流水体氮素的超负荷不仅破坏了水体生态环境,也严重威胁着人类的生存和发展.水体中有机氮、无机氮（氨氮、亚硝氮、硝氮）和分子氮之间的转化（氮循环）有赖于水体中大量的氮循环微生物（固氮细菌、硝化细菌和反硝化细菌）,然而这些氮循环微生物的生长繁殖也受到包括氮素的形态和浓度在内的多种环境因子的影响,这些因素也通过影响氮循环微生物的生长繁殖进而使得水体中氮素的转化速率发生变化,对水体氮污染的防治有不可忽视的作用.本研究通过在沣河设置不同的研究断面,采集水体样品,进行水质分析,并通过现代分子生物学技术（PCR-DGGE）方法对研究断面水体中氮循环微生物（固氮细菌、硝化细菌和反硝化细菌）的群落结构进行分析.再通过统计学软件对所得分子生物学信息与水质环境因子的相关性进行统计学分析,发现沣河水体中氮循环微生物群落结构受到多种环境因子共同影响,且在枯水期和丰水期表现出不同的特征.在丰水期沣河水体中,硝化细菌群落在中游表现出较高的多样性和丰富性,这与沣河中上游农业COD（化学需氧量）、BOD（生化需氧量）氨氮及有机氮污染物排放量较大,沣河水体DO（溶解氧）高有关.水体中的氨氮、亚硝氮、温度的增加是促进水体中硝化细菌的均匀性和丰富度的增高的主要因子,而pH 值的升高,使得水体中硝化细菌的均匀性和丰富度降低.反硝化微生物在中游和下游的多样性和丰富度较高,与有机物及硝酸盐含量相关.水体中的BOD、COD、TP（总磷）、硝氮的增加是促进水体中反硝化细菌的均匀性和丰富度的增高主要相关因子,而DO 的增多则会对部分反硝化细菌产生不利影响,使得水体中反硝化细菌的均匀性和丰富度降低.本研究结果为沣河以及其他河流的污染控制以及基于微生物的生态修复提供了科?     

SBR工艺短程硝化反硝化脱氮试验研究

采用SBR工艺处理人工配制的高氨氮生活污水,考察了pH值、温度、DO等因素对亚硝氟积累的影响.试验结果表明,在常温(25℃左右)条件下,经过20天的驯化培养后,氨氮去除率为98％,亚硝酸氮积累率达到90％,在SBR系统内实现了短程反硝化反应.当pH值在8.0～8.5时,氨氮去除率大于80％,亚硝酸氮积累率大于90％;温...     

A/O MBR处理生活污水效率与菌群多样性的关系

采用缺氧/好氧膜生物反应器（A/O MBR）工艺处理生活污水,试运行了5种不同的工况以确定最佳工艺参数,利用变性凝胶梯度电泳（DGGE）技术研究缺氧池和好氧池（MBR）中细菌群落结构,分析出水水质与细菌种群多样性的关系.结果表明A/O MBR在水力停留时间（HRT）为12 h,污泥停留时间（SRT）为10 d,硝化液回流比为300%,污泥回流比为100%的条件下,对COD、氨氮、总氮有稳定良好的去除,平均去除率分别为96.4%、99.1%、75.8%;系统运行过程中,缺氧池和好氧池中菌群结构发生较大变化,同一工况下两池菌群的相似性通常大于50%,但缺氧池菌群多样性随工况变换而波动较大,好氧池菌群多样性随运行时间而逐渐丰富;缺氧池菌群多样性指数与反硝化效率成正相关关系.     

Fe (Ⅱ)对反硝化过程及其功能微生物群落的影响

以华南稻田土壤为研究对象,通过室内模拟控制实验,研究了Fe （Ⅱ）对厌氧稻田土壤中反硝化过程及其功能微生物群落结构组成与相对丰度的影响.结果表明,加入Fe （Ⅱ）减缓了土壤中NO₃^-的还原,但促进了NO₂^-的还原和N₂O的生成;同时Fe （Ⅱ）只在Soil+Fe （Ⅱ）+NO₃^-处理中发生氧化.通过定量PCR结果发现,Fe （Ⅱ）的加入提高了亚硝酸盐还原基因nirS和N₂O还原基因nosZ的拷贝数;但降低了细胞膜硝酸盐还原基因narG的拷贝数.通过高通量和克隆文库分析发现,Fe （Ⅱ）的加入主要对napA-周质硝酸盐还原微生物群落结构有明显影响,Soil+NO₃^-处理中优势菌是Dechloromonas,而Soil+Fe （Ⅱ）+NO₃^-处理中为Azonexus、Dechloromonas和Azospira.Fe （Ⅱ）对厌氧稻田中的反硝化过程及其功能微生物群落具有显著影响,这对了解华南红壤地区稻田体系中的氮元素循环与铁元素转化的关系具有重要意义.     

水源水库铁还原反硝化菌群的筛选及其脱氮特性研究

为削减水源水库中氮素的浓度,对西安市李家河水库沉积物进行富集驯化,筛选出以Dechloromonas、Acidovorax、Vogesella、Azoarcus等为优势菌属的铁还原反硝化菌群FL6,探究了该菌群的铁还原及反硝化特性.结果表明,在初始pH 7.00±0.2,温度30℃,以硝酸钠为唯一氮源的培养条件下,菌群FL6具有明显的铁还原功能,且表现出高效的反硝化能力.在96 h时菌群FL6对总氮和硝酸盐氮的去除率分别为69.56%、95.23%,且在反应过程中无中间产物的积累,同时nirS型反硝化基因被扩增检测到.响应曲面法（RSM）实验结果表明C/N比5.95,温度24.33℃,初始pH 5.88是菌群FL6去除总氮的最优条件,同时菌群FL6可以耐受低温条件.菌群FL6可以为贫营养水源水库利用无机电子供体强化生物脱氮提供菌源保障.     

一株反硝化细菌的鉴定、功能基因检测及其反硝化特性

采用富集培养和BTB(溴百里酚蓝)平板法从活性污泥中分离出一株高效的反硝化菌ADH1。结合16S rDNA系统发育分析结果和生理生化反应,将该菌鉴定为施氏假单胞菌(Pseudomonas stutzeri),经检测该菌株中存在反硝化功能基因nirS和nosZ,并由此推知其具备完整的反硝化酶系。通过这两种功能基因的系统发育分析,从另一角度证实了菌株ADH1属于Pseudomonas sp.。反硝化特性研究结果表明,在静置条件下,该菌在16 h内对NO3--N的转化率达到96.1%,其中84.7%的NO3--N完全经反硝化作用从培养液中去除,剩余的则被菌体同化吸收;而在150 r/min的振荡培养条件下,该菌在10 h对NO3--N的转化率高达97.8%,TN去除率也超过40%。研究结果表明菌株ADH1可能是一株有着良好应用前景的高效好氧反硝化细菌。     

基于PHB碳源驱动的同时硝化/反硝化除磷过程

构建厌氧/限氧曝气的序批式生物系统(A/OLASBR),以碳源偏低模拟城市污水为对象,在连续(CA)和间歇曝气(IA)模式下,研究以PHB为碳源驱动的同时硝化/反硝化除磷(SNDPR)过程,并考察了PHB、氧化还原电位(ORP)和pH值的变化规律与SNDPR持续稳定性之间的关系.结果表明,在恒定气量为40 L·h-1的CA模式下TN和TP去除率分别为79.9%和92.8%;而IA模式下曝气百分数(AF)和曝气频率(fIA)值为0.5和24时,TN与TP去除率分别为87.9%和93.5%,PHB降解速率平稳,ORP均值均化程度最好,ORP和pH值的稳定性最强.因此,低AF和高fIA的IA模式可缓冲PHB降解速率,均衡硝化与反硝化除磷速率,有利于SNDPR过程的持续稳定,且ORP均值的均化程度与ORP和pH值的稳定性可控制SNDPR过程的持续稳定.     

太湖氮素出入湖通量与自净能力研究

为了探索太湖氮素迁移转化过程,对2009～2010水文年环太湖25条主要河流及太湖梅梁湾、东太湖等典型区域的各形态氮素进行分析,并利用太湖出入湖水量、蓝藻人工打捞量和鱼产量等相关数据,分析计算太湖氮素流动和转化潜力.结果表明太湖全年河道输入氮素总量约7.00×104t,河道出湖氮素总量约4.01×104t.整个水文年中,太湖氮素自净量约3.22×104t,其中反硝化约3.02×104t,沉积物吸附约0.20×104t.在反硝化潜力上,太湖西湖区(如梅梁湾)反硝化潜力远高于东部湖区(如东太湖),而夏季太湖反硝化潜力又高于其它季节.因此,太湖氮素自净作用在湖泊氮素迁移转化中发挥重要作用.     

Ammonium removal pathways and microbial community in GAC-sand dual media filter in drinking water treatment

A GAC-sand dual media filter (GSF) was devised as an alternative solution for drinking water treatment plant to tackle the raw water polluted by ammonium in place of expensive ozone-GAC processes or bio-pretreatments. The ammonium removal pathways and microbial community in the GSFs were investigated. The concentrations of ammonium, nitrite and nitrate nitrogen were monitored along the filter. Total inorganic nitrogen (TIN) loss occurred during the filtration. For 1 mg ammonium removal, the TIN loss was as high as 0.35 mg, DO consumption was 3.06 mg, and alkalinity consumption was 5.55 mg. It was assumed that both nitrification and denitrification processes occur in the filters to fit the TIN loss and low DO consumption. During the filtration, nitritation, nitrification and nitritation-anaerobic ammonium oxidation processes probably occur, while traditional nitrification and denitrification and simultaneous nitrification and denitrification processes may occur. In the GSFs, Nitrosomonas and Nitrospira are likely to be involved in nitrification processes, while Novosphingobium, Comamonadaceae and Oxalobacteraceae may be involved in denitrification processes.