以纤维素物质为反硝化碳源和载体去除水中硝酸盐

利用纤维素物质作为反硝化碳源和载体是目前去除水中硝酸盐常用的方法 ,该方法具有成本低廉、取材广、无二次污染等优点。对基于纤维素物质的固相反硝化技术使用的可行性、影响因素以及技术难题等进行了论述,并提出了纤维素物质固相反硝化技术的发展方向和亟需解决的技术难题以及该方法的弊端,为纤维素物质固相反硝化技术的发展和研究提供有益参考。     

Ammonium transformation in paddy soils affected by the presence of nitrate

Coupled nitrification and denitrification is considered as one of the main pathways of nitrogen losses in paddy soils. The effect of NO₃ ^– on NH₄ ⁺ transformation was investigated by using the ¹⁵N technique. The paddy soils were collected from Wuxi (soil pH 5.84) and Yingtan (soil pH 5.02), China. The soils were added with either urea (18.57 mol urea-N enriched with 60 atom% ¹⁵N excess) plus 2.14 mol KNO₃-N (natural abundance) per gram soil (U+NO₃) or urea alone (U). The KNO₃ was added 6 days after urea addition. The incubation was carried out under flooded condition in either air or N₂ gas headspace at 25°C. The results showed that in air headspace, ¹⁵NH₄ ⁺ oxidization was so fast that about 10% and 8% of added ¹⁵N in the treatment U could be oxidized during the incubation period of 73 hours after KNO₃ addition in Wuxi and Yingtan soil, respectively. The addition of KNO₃ significantly inhibited ¹⁵NH₄ ⁺ oxidation (p<0.01) in air headspace, while it stimulated ¹⁵NH₄ ⁺ oxidation in N₂ gas headspace, although the oxidation was depressed by the N₂ gas headspace itself. Therefore, the accumulation of NO₃ ^– would inhibit further nitrification of NH₄ ⁺ at micro-aerobic sites in paddy soils, especially in paddy soils with a low denitrification rate. On the other hand, NO₃ ^– would lead to oxidation of NH₄ ⁺in anaerobic bulk soils.     

The effects of nitrate and nitrate‐supplemented leachate addition on methanogenesis from Municipal Solid Waste

The recirculation of nitrified leachate through landfill sites, followed by in situ denitrification, represents a novel and more sustainable approach for the removal of ammonia from leachate, prior to discharge. The effects of nitrate and leachate supplementation on methanogenesis in Municipal Solid Waste (MSW) were studied in batch cultures. The addition of a range of nitrate concentrations to MSW samples had an inhibitory effect on methanogenesis. The effects were dose‐dependent, such that recovery of methane production was recorded within 5 and 23 days with added 100 and 750 mg NO₃ dm^?3, respectively. Even after 24 days, no recovery was observed in cultures challenged with 1000 mg NO₃ dm^?3. The enumeration of denitrifying bacteria in a range of fresh, actively methanogenic and aged, well‐decomposed MSW confirmed the potential of MSW for rapid denitrification. Methanogenesis was not inhibited by the addition of leachate (20–100% strength) that contained high concentrations of VFAs. However, when the same leachate was supplemented with nitrate (250 mg NO₃ dm^?3), methanogenesis was inhibited by the addition of leachate concentrations ≥20%, which was attributed to inhibition of denitrification by VFAs. Propionate accumulated, confirming the importance of methanogenesis as an electron sink. With the removal of nitrate and the recovery of methanogenesis, net propionate concentrations decreased. Copyright © 2004 Society of Chemical Industry     

不同碳源类型对生物除磷过程释放磷的影响

厌氧释放磷是生物除磷的重要部分,释放磷不充分是生物除磷不稳定的主要原因。为了研究碳源种类对厌氧生物除磷的影响,以A2/O氧化沟工艺好氧末端活性污泥为研究对象,投加乙酸钠、丙酸钠、葡萄糖、甲醇和乙醇等碳源,在厌氧和缺氧状态下进行释放磷试验研究。结果表明：（1）在厌氧条件下,聚磷菌（PAOs）以乙酸钠或丙酸钠为碳源释放磷速率很快,120 min平均比释放磷速率分别为290.5和236.7 mg P·（g VSS）-1·d-1;PAOs利用葡萄糖、乙醇和甲醇释放磷速率较低,比释放磷速率分别为49.4、38.8和8.91 mg P·（g VSS）-1·d-1;（2）在缺氧条件下,PAOs以乙酸钠或丙酸钠为碳源释放磷速率与厌氧状态下释放磷速率相差不大,而其他3种碳源作用下,PAOs并不释放磷;（3）初始NO-3过高时,乙酸钠作为碳源,PAOs在释放磷结束后利用NO-3作为电子受体进行反硝化吸收磷。     

剩余污泥发酵产物作为碳源的反硝化特性研究

研究了将经乙醇型发酵后剩余污泥上清液作为反硝化外加碳源的可行性,并进行了上清液、甲醇和生活污水作为外加碳源的对比试验。结果表明,在相同的试验条件下,采用上清液和生活污水作为反硝化碳源时,系统反硝化过程中NO3--N的降解过程分为三个阶段,而以甲醇作为碳源时,NO3--N的降解过程为两个阶段;对比试验还发现,采用上清液代替甲醇作为反硝化系统的外加碳源,可在保持高反硝化速率的同时降低运行成本。     

Inhibition of sulfide on the simultaneous removal of nitrate and p‐cresol by a denitrifying sludge

BACKGROUND: Many industrial discharges, such as those generated from petrochemical refineries, contain large amounts of sulfurous, nitrogenous and organic contaminants. Denitrification has emerged as a suitable technology for the simultaneous removal of these pollutants in a single reactor unit; however, more evidence is demanded to clarify the limitations of denitrification on the simultaneous removal of sulfide and phenolic contaminants and to optimize the biological process. The aim of this study was to evaluate the capacity of a denitrifying sludge to simultaneously convert sulfide and p‐cresol via denitrification. RESULTS: Sulfide was the preferred electron donor over p‐cresol, imposing a 5 h lag phase (required for complete sulfide removal) on organotrophic denitrification. Addition of sulfide (20 mg S^2? L^?1) to p‐cresol‐amended denitrifying cultures also decreased the reduction rate of nitrate and nitrite, as well as the production rate of nitrogen gas. Nitrite reduction rate was the most affected step by sulfide, decreasing from 35 to 21 mg N (g VSS d)^?1. A synergistic inhibitory effect of nitrate and sulfide was also observed on nitrite reduction. Despite the effects of sulfide on the respiratory rates monitored, complete removal of nitrate, sulfide and p‐cresol could be achieved after 48 h of incubation. CONCLUSION: Our results suggest that simultaneous removal of sulfide and p‐cresol could be achieved in denitrifying reactors, but a large hydraulic residence time may be required to sustain an efficient process due to inhibitory effects of sulfide. Copyright © 2008 Society of Chemical Industry     

不同碳源对EBPR系统厌氧计量学参数的影响

采用乙酸/丙酸交替、葡萄糖、实际生活污水为碳源长期驯化的三个强化生物除磷系统,研究了不同碳源对磷的释放和聚羟基烷酸(PHA)转化的影响、聚磷菌种群结构以及微生物代谢PHA和糖原的厌氧化学计量学。结果表明,从182 d起三个系统均获得稳定的除磷性能,第300 d三个系统内聚磷菌所占全菌的比例分别达到:89%±3%、55%±3%、45%±4%。乙酸、葡萄糖、生活污水为碳源时,聚磷菌细胞内贮存聚羟基丁酸(PHB)和聚羟基戊酸(PHV),丙酸为碳源PHA完全由PHV组成,四种类型碳源都未检测到聚二甲基三羟基戊酸(PH2MV)的生成。计量学研究表明:聚磷菌吸收1 C-mol的乙酸,细胞内合成1.15 C-mol PHB,0.15 C-mol PHV,分解0.47 C-mol糖原;吸收1 C-mol的丙酸生成0.44 C-mol的PHV,分解0.271 C-mol的糖原;吸收1C-mol的葡萄糖生成极少量的PHB和0.16C-mol PHV,分解0.16 C-mol糖原;以实际生活污水为碳源,消耗1 mg的COD,合成0.98 mg PHB、0.13 mg PHV(以COD计)。当以乙酸为碳源时获得最高的厌氧释磷量及最大的释磷速率,分别为:134 mg·L^-1和23.80 mg P·(g VSS)^-1·h^-1。以丙酸与葡萄糖为碳源时释磷速率相似,以生活污水为碳源的情况下释磷速率最小。     

缓释碳源材料的选择与制备探究

固体缓释碳材料可在地下水异氧反硝化过程中作为电子供体。目前,所研究的缓释碳源主要分为两大类:一类为天然释碳材料;另一类为人工合成释碳材料。复合释碳材料的制备工艺主要为挤出成型法、注塑成型法和压膜成型法3类。     

The effect of fertiliser type and application rate on denitrification losses from cut grassland in Northern Ireland

Denitrification losses were measured using the acetylene inhibition technique adapted for a coring procedure. Two soils under a cut ryegrass sward were used. One soil was a freely-drained clay loam receiving under 900 mm rainfall annually, the other soil being a poorly-drained silty clay receiving over 1100 mm rainfall annually. Swards at each site received up to 300 kg N ha^–1 yr^–1 of calcium ammonium nitrate (CAN), urea or a new fertiliser mixture GRANUMS (30% ammonium nitrate, 30% urea, 10% ammonium sulphate, 30% dolomite). For both soils the rate of denitrification exceeded 0.1 kg N ha^–1 day^–1 only when the air-filled porosity of the soil was < 30% v/v and soil nitrate was > 2 mg N kg^–1 in the top 10cm of the profile and when soil temperature at 10 cm was > 4°C. When the soils dried such that their air-filled porosity was > 30% v/v, denitrification rates decreased to < 0.08 kg N ha^–1 day^–1. Highest rates (up to 3.7 kg N ha^–1 day^–1) were observed on the clay soil following application of 94 kg N ha^–1 CAN to soil near field capacity in early summer 1986. Losses from CAN were approximately 3 times those from urea for a given application. Denitrification losses from the GRANUMS treatment were, overall, intermediate between those from CAN and urea but the daily losses more closely resembled those from the CAN treatment. The impeded drainage on the clay soil, where soil moisture contents remained close to field capacity throughout the year, showed denitrification losses roughly 3 times those observed on the more freely drained clay-loam for any given treatment. Over a 12-month period, N losses arising from denitrification were 29.0 and 10.0 kg N ha^–1 for plots receiving 300 kg N ha^–1 CAN and urea, respectively, on the well drained clay-loam and 79.0 and 31.1 kg N ha^–1 respectively, for identical plots on the poorly drained clay soil. Annual denitrification losses from control plots were < 1 kg N ha^–1 on both soils.     

我公司结晶硝铵冷却系统改造

介绍该公司采用振动流化床与旋风除尘器，布袋除尘器，利用氨空调器制出的冷，干空气冷却高温结晶硝铵，这样避开了硝铵在85℃时的晶变温度区，对防止硝铵结块起到了很好的作用。     

硝酸铈铵复盐制备工艺研究

对硝酸铈铵复盐的制备工艺进行了研究。分析了反应物的加入量、反应温度、反应时间以及其它工艺条件对制备硝酸铈铵复盐产品质量的影响。得出了制备分析纯硝酸铈铵复盐的方法。该方法可获得纯度达99%以上的橘红色硝酸铈铵复盐,收率达85%以上。     

稻壳作为反硝化碳源在海水中的脱氮性能研究

以稻壳为反硝化碳源,研究了稻壳的营养组成、微观形貌、孔隙结构、在海水中的释碳速率以及作为反硝化碳源在海水中的脱氮效果。结果表明,稻壳中含有能被微生物利用的粗纤维、淀粉和粗蛋白等,总有机碳达到58%以上;稻壳含有大量亲水官能团,表面粗糙且拥有大量孔隙结构,非常利于微生物附着生长。以稻壳为反硝化碳源,海水中硝酸盐去除率可达59%,且具备较好的持续供碳能力,可满足其作为碳源被微生物持续利用的需求。     

硝态氮在经济作物专用肥的应用

烟草、棉花、辣椒等经济作物的专用肥中配入一定比例的硝态氮 ,可提高其产量、质量 ,介绍几种经济作物专用肥的原料配比及产品质量     

Effect of wheat and barley varietal differences in nitrate concentration on plant analysis interpretation

Wheat and barley varieties from breeding plots in advanced yield trials were tested for NO₃ concentration in their stems at the tillering stage. The study was carried out for three years, at three different locations with a high number of varieties, aiming to determine whether there are varietal differences which could affect the interpretation of prognostic standards set up in a previous study.From nine comparisons between 12 different varieties it was shown that differences in NO₃ concentration occurred on only three occasions and these were due to factors which affect NO₃ in plants, other than genotypic.The study concluded that varietal differences in NO₃ concentration are not a critical consideration for the interpretation of prognostic standards for genotypes which have been developed for certain environmental conditions.     

固液碳源对反硝化脱氮及污泥产量影响研究

分别用乙酸钠和聚己内酯作为外加碳源,对反硝化滤池中固液碳源对污水厂出水脱氮的反硝化效果和污泥产量进行了对比研究。结果表明,液体碳源的反硝化速率更快,可达到2.19 g/(L·d),氮去除率最高可达到95%以上,固体碳源的反硝化速率低于液体碳源,受HRT的影响更大。固体碳源中NO2^--N几乎不积累,液体碳源更容易积累且积累量与HRT有关,2种碳源中均存在异化性硝酸盐还原成铵反应,但出水NO2^--N和NH4^+-N含量均未超标。固体碳源的出水COD稳定低于50 mg/L,当HRT缩短时,液体碳源出水COD存在超标的风险。液体碳源的浓缩污泥产量和单位污泥产量分别为固体碳源的3倍和1.6倍。使用固体碳源可以有效减少污泥的产生。     

Electrodeposition of silver from nitrate solution: Part II. Mechanism of the effect of phosphate ions

The mechanism of compact Ag-film formation by electrolysis from nitrate solution with addition of small amounts of phosphate ions is elucidated. It is shown that the phosphate ions exert their effect by lowering the exchange current density. Consequently, the radii of nucleation exclusion zones also diminishes, thus producing conditions stimulating electrodeposition of continuous thin Ag-film.     

盐度入侵城市污水处理厂对淡水活性污泥的毒性抑制

盐度入侵城市污水处理厂改变了活性污泥的胞外渗透压环境,影响生物系统的生物活性和污染物降解能力。采用MUCT工艺处理真实生活污水,模拟了盐度入侵对系统处理效率的影响。并结合污染降解动力学和抑制动力学建立了盐度抑制模型,系统地评测了盐度对活性污泥功能性微生物的毒性抑制。结果表明,盐度入侵造成了功能性微生物的活性损失,干扰了正常的污水处理能力。毒性抑制显著地降低了好氧微生物的呼吸作用,以此作为毒性评估的依据会造成对抑制作用的高估。而以底物降解速率评估盐度毒性抑制可以很好地指示污水处理效率。盐度对有机物降解异养菌、硝化菌和反硝化菌抑制的IC₅₀值分别是20.64 g·L^-1、11.61 g·L^-1、10.88 g·L^-1。     

粒状硝酸钾的研制与开发

本文应日本及新疆吐鱼番化工有限公司的要求,对提纯后的硝酸钾进行了制粒研究,并由日本全农肥料农药部对研制的粒状硝酸钾进行了性能测定。