连续流动分析仪测定水中硝酸盐氮及亚硝酸盐氮

连续流动分析仪测定水中总氮含量的原理是利用高温高压紫外光,将水中各种形态的氮元素氧化分解至化合价最高的NO_3~-态,再利用镉铜还原柱将NO_3~-定量还原成NO_2~-,检测器于540 nm处测出NO_2~-的浓度,结果以总氮的形式显示。因此可以通过改变进样方式和反应方式,实现硝酸盐氮和亚硝酸盐氮的测定。     

二维电极电解法去除水中硝酸盐试验研究

目前硝酸盐污染已经严重影响了地下水水质,对饮用水安全构成了一定威胁。本研究拟采用电化学方法去除水体中硝酸盐,探究其机理、动力学、影响因素及实际地下水处理方法,为地下水脱氮提供参考。研究结果表明:在无氯离子体系下,30.0 mg/L的硝酸盐在2.0 A电流下电解,其一级反应动力学常数为0.040 h-1,产物中54%为氨氮,46%为氮气。在添加300.0 mg/L氯离子条件下电解,一级反应动力学常数为0.029 h-1,其产物主要为氮气。硝酸盐去除速率随着硝酸盐初始浓度和电流增加而增加,随着氯离子浓度增加而略微减少。对实际地下水水样的电解结果表明,20.0 mg/L的硝酸盐在2.0 A、100.0 mg/L氯离子条件下电解,其一级反应动力学常数为0.031 h-1,产物主要为氮气。二维电极电解过程中,硝酸盐扩散至阴极表面速率较慢,电解效率较低。     

一株青霉菌异养硝化和好氧反硝化特性的研究

从活性污泥中分离出一株青霉菌,培养特性为中温好氧性。初步研究表明:该菌株可利用多种含碳化合物及含氮化合物作为唯一碳源和氮源,并将含氮化合物转化为亚硝态氮,在好氧条件下,能还原硝酸盐,具有同步硝化和反硝化作用。在实验条件下,以铵盐作为反应底物,培养24 h后,溶液中ρ(NO2-)为0.35μg/mL,对硝酸盐有较强的还原能力,24~72 h培养后,溶液中的ρ(NO2-)为3~5μg/mL;在pH=5~11,48 h后对人工合成污水的氨氮去除率可达90%~97.7%。     

潇河表层沉积物中氮素分布特征及其污染评价

为了研究河道表层沉积物中氮素分布特征,以潇河为研究区,选取7个采样点,研究表层沉积物中两种形态的氮素——氨氮和硝酸盐氮,测定分析其含量、分布特征及成因,并探究其与有机质之间的关系。其中氨氮用KCl浸提-靛酚蓝比色法测定,硝酸盐氮用酚二磺酸比色法测定,沉积物中有机质的测定用重铬酸钾法。在测定结果的基础上,采用单项指标标准指数法对沉积物中氮的污染程度进行评价。结果表明:1潇河表层沉积物中氮素总量表现为中下游段高于中上游段的特征。就两个河流段而言,同时呈逐渐下降的趋势。氮素总量受到上覆水体氮营养盐水平、溶解氧含量及沉积物的氧化还原电位、沉积物中有机质的降解影响。氨氮含量大于硝酸盐氮,二者平均值之比为1.38∶1,表明潇河沉积物还原程度较低。2利用线性回归分析可知,沉积物中硝酸盐氮和有机质含量呈显著正相关。3潇河沉积物中总氮的含量较高,一半以上采样点的标准指数超过1,说明潇河沉积物环境质量受氮的污染相对严重。     

钴铝水滑石涂膜电极的制备及电催化还原硝酸盐的研究

硝酸盐污染物广泛分布于地表水与地下水中,为了探索检测及去除水体中硝酸盐污染物的有效方法,采用双滴定法制备了不同摩尔比的钴铝水滑石化合物,通过X射线衍射、场发射扫描电子显微镜对钴铝水滑石化合物进行表征。结果表明:钴铝摩尔比为1∶1,2∶1,3∶1时,均形成了水滑石特有的结构。实验利用钴铝水滑石制备成涂膜电极,通过线性伏安扫描法研究各电极材料电化学还原硝酸盐的效果。钴铝摩尔比为2∶1时电化学还原硝酸盐的效果最好,并且还原峰电流与硝酸盐浓度及扫描速率呈线性关系。实验结果表明:钴铝水滑石涂膜电极可应用于电化学检测硝酸盐和去除硝酸盐的工艺中。     

新型亚硝化工艺开发研究

采用长污泥龄、低氧或微氧工艺控制亚硝化反应,成功地开发出了一种全新的亚硝化工艺,连续运转245d。试验结果表明,新型亚硝化工艺氨氮转化率平均为68.1%,亚硝酸盐氮生成率为63.7%,硝酸盐氮生成率平均为1.2%,氨氮几乎全部转化为亚硝酸盐氮,未发生硝酸盐积累。出水中氨氮负荷为0.238kgN/(m3·d),亚硝酸盐氮负荷为0.526kgN/(m3·d),污泥龄为198d,污泥比增长率为0.0051d-1,污泥产率为0.0375gVSS/gNH3-N。长污泥龄、低溶解氧、游离氨、亚硝酸抑制等的共同作用,是实现稳定亚硝化的关键。     

黄河干流水样三氮测定保存方法的探讨

<正> 一、前言三氮在水质监测中系指氨氮、亚硝酸盐氮、硝酸盐氮等氮化物的三种存在形态。一般地表水中氨氮、亚硝酸盐氮、硝酸盐氮含量不大,只有生活污水、工业废水中含量较高。当水体中氨氮、亚硝酸盐氮含量突然增高,说明水体正受到污染;当水体中氨氮、亚硝酸盐氮含量很低,主要是硝酸盐氮时,则说明水体基本得到自净。因此氨氮、亚硝酸盐氮、硝酸盐氮在水体中的含量是衡量水     

pH值对弱透水层中硝酸盐迁移转化的影响

为研究硝酸盐在不同pH值条件下通过弱透水层的越流迁移机理及转化形式设计了室内试验,用天然黏土模拟弱透水层渗透介质,配制硝酸盐溶液作为渗透液,在高渗透压条件下,观察NO3-通过弱透水层的迁移转化过程。结果表明:不同pH值条件下硝酸盐通过弱透水层向下迁移的能力很弱;由于黏土的pH值为5.8,土壤中分布的正电荷多于负电荷,所以硝酸盐大量减少是因为结合水强化的电性吸附造成的。硝酸盐在弱透水层中的迁移过程表现为大部分被弱透水层吸附,在试验后期发生了异化还原作用。硝酸盐浓度随时间的增加呈指数下降。同时发现硫酸盐对硝酸盐的异化还原反应具有较弱的阻滞作用,氯离子与硝酸盐之间显示微弱竞争吸附关系。     

江水倒灌污染物的水文地球化学迁移转化过程

以松花江哈尔滨段污染为例,通过室内模拟槽研究了江水倒灌过程中主要氧化还原敏感性物质的水文地球化学迁移转化过程。研究结果表明,氧化还原灵敏性物质(如SO42-、Fe3+、NO3-、COD、HCO3-)在不同水文地球化学条件下形成各自的氧化还原优势带,各氧化还原污染物之间存在显著相关性,其迁移转化过程主要是消耗有机物的氧化还原反应和消耗氧的氧化还原反应。     

冬季沁河(河南段)水化学特征

研究冬季沁河(河南段)的水化学特征为沁河水环境保护以及水资源利用提供依据。采集沿沁河及黄河9个断面样品并对样品的主要阴、阳离子和重金属进行检测,在此基础上运用水化学分析和因子分析法分析了沁河的主要水化学特征。结果表明:沿水流方向沁河取样断面由上到下水化学类型由Ca2+-SO42-+HCO3-型转变为Ca2+-HCO3-型;钙离子占阳离子总量51%,碳酸氢根离子占阴离子总量51%。黄河的水化学离子组成与沁河有较大区别,主要体现在钠离子和氯化物。沁河各点处的硝酸盐含量基本一致,平均为15.34mg/L(以NO3-计);氨氮浓度沿沁河径流路径呈上升趋势,平均浓度为1.42 mg/L(以NH3-N计)。冬季沁河(河南段)的水化学类型主要受控于自然因素,沁河水体中的硝酸盐主要来自地下水,氨氮主要来源于人类排放的污废水。     

Electrochemical treatment of residual ammonia nitrogen in biologically pretreated coking wastewater with three-dimensional electrodes

The electrochemical oxidation of the residual ammonia nitrogen contained in biologically pretreated coking wastewater using three-dimensional electrode system was studied. The results show the Ti/RuO2/IrO2 anode plates and the coke have good surface characteristics for the purpose of this study. In addition, studies also show that the three-dimensional electrode system should be able to give a satisfied solution to the residual bio-refractory ammonia nitrogen in biologically pretreated coking wastewater in comparison to conventional two-dimensional electrodes. At coke size of 10-20 mesh, electrode distance of 1.0 cm and current density of 4.5 mA/cm2, the residual ammonia nitrogen in the three-dimensional electrode system was almost completely removed in 60 min.     

Biozeolite capping for reducing nitrogen load of the ancient canal in Yangzhou City

Biozeolite capping for reducing nitrogen (N) load of an eutrophic canal in Yangzhou City was studied. Biofilm formation on biozeolite was cultivated by use of isolated nitrifiers and denitrifiers. Varying conditions including dissolved oxygen (DO) and origins of isolated bacteria were considered in our experiments. Long-term sediment incubation experiment results showed that the reduction efficiency of total nitrogen (TN) of overlying water by biozeolite capping were in the range of 47.61-57.64% under the condition of DO<1 mg L(-1). There was no obvious difference in TN reduction efficiency between natural biozeolite (indigenous bacteria) and artificial biozeolite (isolated bacteria). However, the reduction efficiency of TN and nitrate nitrogen (NO(3)(-)-N) were respectively in the ranges of 67.38-76.12% and 69.38-76.12% under the condition of DO 1.5-5 mg L(-1). The reduction efficiencies of TN and NO(3)(-)-N by artificial biozeolite were improved by 25.99-27.25% and 17.50-24.15% respectively than those by natural biozeolite. Moreover, no significant difference was found for reducing N load by the isolated bacteria with different origins. TN contents of surface sediments and ammonia nitrogen concentrations of sediment interstitial water in biozeolite capping systems declined obviously after experiments. Biozeolite capping is an effective technique for reducing N load of the Yangzhou canal.     

氮元素降解随流速的变化规律研究

本文介绍了采用循环环境水槽试验对流速对氮元素降解过程的影响进行的研究。研究中,分别监测了不同流速条件下水体的氨氮、硝酸盐(NO_3~--N)、亚硝酸盐(NO_2~--N)浓度随时间的变化过程,并分析了pH随流速变化对氮元素主要降解过程的影响。结果表明:实验水体pH主要受氮元素迁移转化的影响,其值的变化与氨氮、硝酸盐(NO_3~--N)、亚硝酸盐(NO_2~--N)的浓度变化显著性相关,其与流速同样关系紧密,无论是氨化反应占主导阶段,还是硝化、反硝化反应占主导的阶段,均是流速越大,pH越高。     

昌平区地下水氮素空间分布特征分析

对昌平平原区浅层、深层及基岩地下水的氮素空间分布特征进行了分析,从垂向和水平向对氮素分布情况作了对比,发现昌平平原区的浅层、深层及基岩层地下水中氮素含量较高,其中浅层地下水中硝态氮和氨氮含量较高,深层地下水为氨氮含量较高,基岩层亚硝氮含量较高,且从浅层到深层、基岩层．氮素含量逐渐降低。结合氮素的分布及迁移转化规律分析可知,研究区地下水氮素来源于地表含氮物质的下渗转化。     

Ammonia removal in the catalytic wet air oxygen process of landfill leachates with Co/Bi catalyst.

Oxidation of ammonia in landfill leachates in the catalytic wet air oxidation (CWAO) process was investigated with Co/Bi catalyst. The characterization of the Co/Bi catalyst was carried out by the X-ray diffraction technique. Studies of ammonia removal from the landfill leachates by CWAO showed that Co/Bi catalyst exhibited higher activities for both total organic carbon (TOC) and ammonia with removal levels of 99% for TOC and 98% for ammonia, respectively. Results also indicated that large amounts of ammonia were produced during the elimination of nitrogenous organic compounds in the CWAO process and the further oxidation of ammonia gave off essentially N2 under 240 degrees C. When the system temperature reached above 240 degrees C, ammonia oxidation rate was much higher with nitrate dominating in the effluent; a very small amount of nitrite was observed in the reaction process, it possibly acts as the intermediate of nitrate ion and molecular nitrogen formation, showing that the system temperature had significant effects on the ammonia oxidation and reaction selectivity towards the production of molecular nitrogen or nitrate.     

洱海典型小流域丰水期农业面源氮污染来源解析

农业面源污染是近年来导致洱海水质不断恶化的主要因素。选取洱海地区典型小流域,分析了林地、耕地以及居民区地表径流中硝酸盐氮与铵态氮的氮、氧同位素特征,进而解析其来源。结果表明:林地径流中硝酸盐氮来源于大气降雨和土壤的比例分别为8.53%和91.47%,铵态氮来源于大气降雨和土壤的比例分别为19.78%和80.22%;耕地径流中硝酸盐氮来源于大气降雨、土壤和化肥的比例分别为5.90%,68.76%,25.34%,铵态氮则主要来源于土壤;居民区径流中硝酸盐氮来自于大气降雨、生活污水和动物粪便的比例分别为3.32%,55.42%,41.26%,铵态氮则主要来源于生活污水与动物粪便。研究成果为控制洱海流域农业面源污染提供了有效途径。     

The effects of deep zones on wetland nitrogen processing.

Twelve research wetlands were operated under varying conditions at a site west of the city of Phoenix. These were constructed as a triplicated design, with zero, one, two and three internal deep zones, all containing an inlet distribution and an outlet collection deep zone, together comprising 12.5-35% of the wetland areas. The water supply was partially nitrified effluent from a city wastewater treatment plant. Total nitrogen was reduced by about 50%, from inflow concentrations between 6 and 8 mg/L. Speciation of the inflow was approximately 25% organic nitrogen, 25% ammonium nitrogen and 50% nitrate nitrogen. Typical outflow concentrations were about 1.2 mg/L organic, 0.5 mg/L ammonium and 0.0-2.5 mg/L nitrate. Rate constants for total nitrogen were 15-20 m/year at 20 degrees C, and 20-30 m/year for nitrate, which agree well with other project reports. Temperature factors averaged 1.100 for total nitrogen, and 1.184 for nitrate. There were no differences in the internal hydraulics with deep zone numbers. Deep zone numbers in the wetlands did not affect nitrogen treatment performance. No differences with deep zone numbers were found for temperature, dissolved oxygen, pH, or nitrogen removals or rate constants. In conjunction with other reported results, there appears to be no large treatment benefit or detriment of incorporating internal deep zones in free water surface wetlands.     

生物接触氧化流化床处理氨氮污水的实验研究

为了提高生物接触氧化流化床处理氨氮污水的脱氮效果,采用生物接触氧化流化床在自然温度下处理人工配制模拟生活污水实验的方法,研究了氨氮污水脱氮处理的可行性、方法与效果。实验结果表明:氨氮被氧化成硝酸可由两类独立的细菌分别催化完成;反应的适宜温度为20~35℃;亚硝酸菌的最适pH值为7~8.5之间,硝酸菌为6~7.5;亚硝酸菌和硝酸菌溶解氧质量浓度在0.5 mg/L以上才能取得较好的硝化效果。反应器内填料粒径在10 mm左右有利于提高氨氮的去除效率;间歇式进水方式使活性污泥具有良好的沉降性,可为氨氮的去除提供良好的环境条件。     

Development and optimisation of VFA driven DEAMOX process for treatment of strong nitrogenous anaerobic effluents.

The recently proposed DEAMOX (DEnitrifying AMmonium OXidation) process combines the anammox reaction with autotrophic denitrifying conditions using sulphide as an electron donor for the production of nitrite from nitrate within an anaerobic biofilm. This paper firstly presents a feasibility study of the DEAMOX process using synthetic (ammonia + nitrate) wastewater where sulphide is replaced by volatile fatty acids (VFA) as a more widespread electron donor for partial denitrification. Under the influent N-NH+4/N-NO3(-) and COD/N-NO3(-) ratios of 1 and 2.3, respectively, the typical efficiencies of ammonia removal were around 40% (no matter whether a VFA mixture or only acetate were used) for nitrogen loading rates (NLR) up to 1236 mg N/l/d. This parameter increased to 80% by increasing the influent COD/N-NO3(-) ratio to 3.48 and decreasing the influent N-NH4 +/N-NO3(-) ratio to 0.29. As a result, the total nitrogen removal increased to 95%. The proposed process was further tested with typical strong nitrogenous effluent such as reject water (total N, 530-566 mg N/l; total COD, 1530-1780 mg/l) after thermophilic sludge anaerobic digestion. For this, the raw wastewater was split and partially ( approximately 50%) fed to a nitrifying reactor (to generate nitrate) and the remaining part ( approximately 50%) was directed to the DEAMOX reactor where this stream was mixed with the nitrified effluent. Stable process performance up to NLR of 1,243 mg N/l/d in the DEAMOX reactor was achieved resulting in 40, 100, and 66% removal of ammonia, NOx(-), and total nitrogen, respectively.     

Water chemistry gradient in a degraded bog area.

Surface and ground water was sampled in a degraded bog area 36 times during 1993 - 2003 at Five representative points: point E (natural area with Sphagnum as the main vegetal cover), point W (boundary between the natural and degraded areas), point W' (area installed with vinyl sheeting), point WW (area where Sasa thrives), and point NC (area with naturally formed ditches). Analysis of variance (ANOVA) was conducted for parameters measured in surface water and ground water at 0.5, 1.0, 1.5, and 2.0 m depths. "Sampling point" (i.e. locations along the degradation gradient) accounted for most of the variation in surface and ground water chemistry. It accounted for 30-80% of the total variation in pH, electrical conductivity, ammonia, dissolved nitrogen, major cations (Na+, K+, Ca2+, Mg2+), alkalinity and dissolved organic carbon. "Year" accounted for more variation in nitrate, nitrite, chloride, and sulfate than the sampling point did, but the variation in dissolved reactive phosphorus and dissolved phosphorus concentrations was not based on any of the calculated variables.