5种植物材料的水解释碳性能及反硝化效率

碳源在硝酸盐去除过程中起电子供体的作用,是生物反硝化反应的关键物质之一。为解决污水处理脱氮时碳源不足抑制反硝化反应造成脱氮效率低的问题,本研究选取风车草、甘蔗渣、芦竹、美人蕉和稻草秆5种植物材料作为反硝化碳源,探讨不同植物材料的水解释碳能力和释放规律;并进一步以其水解液作为外加碳源,探讨其对反硝化脱氮效率的影响。研究结果表明,植物材料水解释碳过程符合二级动力学反应规律,不同植物材料的释碳能力具有显著性差异,以甘蔗渣在固液比1∶80时COD释放当量最大,为45.45 mg/L;添加植物水解液可显著提高反硝化脱氮效率,以芦竹水解液脱氮效果最好,达到71.9%。此外,碳氮比是影响脱氮效率的重要因素之一,以碳氮比为9时反硝化脱氮效果最佳。     

Effects of macrophytes and external carbon sources on nitrate removal from groundwater in constructed wetlands

Several microcosm wetlands unplanted and planted with five macrophytes (Phragmites australis, Commelina communis, Penniserum purpureum, Ipomoea aquatica, and Pistia stratiotes) were employed to remove nitrate from groundwater at a concentration of 21-47 mg NO3-N/l. In the absence of external carbon, nitrate removal rates ranged from 0.63 to 1.26 g NO3-N/m2/day for planted wetlands. Planted wetlands exhibited significantly greater nitrate removal than unplanted wetlands (P<0.01), indicating that macrophytes are essential to efficient nitrate removal. Additionally, a wetland planted with Penniserum showed consistently higher nitrate removal than those planted with the other four macrophytes, suggesting that macrophytes present species-specific nitrate removal efficiency possibly depending on their ability to produce carbon for denitrification. Although adding external carbon to the influent improved nitrate removal, a significant fraction of the added carbon was lost via microbial oxidation in the wetlands. Planting a wetland with macrophytes with high productivity may be an economic way for removing nitrate from groundwater. According to the harvest result, 4-11% of nitrogen removed by the planted wetland was due to vegetation uptake, and 89-96% was due to denitrification.     

Denitrification using PBS as carbon source and biofilm support in a packed-bed bioreactor

Biodegradable polymer was used as carbon source and biofilm support for nitrate removal from aqueous solution as an attractive alternative for biological denitrification. The objective of this paper was to investigate the denitrification performance and microbial community of a packed-bed bioreactor using poly (butanediol succinate) (PBS), a biodegradable polymer, as carbon source and biofilm support. NO₃–N concentration was determined by UV spectrophotometer. NO₂–N concentration was assayed by hydrochloric acid naphthyl ethylenediamine spectrophotometry method. Total organic carbon (TOC) was measured using a TOC analyzer. The morphology of the samples was observed using an environmental scanning electron microscope (ESEM). The microbial community was analyzed by pyrosequencing method. The experimental results showed that an average removal efficiency of nitrate was 95 %. ESEM observation and FTIR analysis indicated the changes of PBS granules before and after microbial utilization. Pyrosequencing results showed that Betaproteobacteria predominated, and most of PBS-degrading denitrifying bacteria were assigned to the family Comamonadaceae. Denitrifying bacteria accounted for 13.02 % in total population. The PBS granules were suitable support and carbon source for denitrifying bacteria.     

A review of denitrification in on-site wastewater treatment systems

The literature on denitrification and its relationship to on-site wastewater systems was reviewed. Denitrification is an important nitrogen removal mechanism in some alternative on-site wastewater systems. Nitrogen removal rates for conventional septic tank systems may vary from 0% to 35% but should be increased by pressure dosing. Denitrification rates for conventional on-site wastewater systems will depend upon loading rate, soil types and the height of the water table below the soil adsorption bed. Some alternative on-site wastewater systems may remove 70% to 80% of the nitrogen if a supplemental carbon source is used. Methanol and household wastes have been used as carbon sources. Crust formation in a soil adsorption bed may improve denitrification.     

不同碳源添加量对垂直流人工湿地污水处理效果的影响

以垂直流人工湿地小试系统为研究对象,采用碱处理过的千屈菜(Lythrum salicaria)作为反硝化碳源补充材料,探讨了不同碳源添加量对系统COD及氮、磷去除效果的影响。结果表明,一定剂量经过碱处理的千屈菜材料可以为人工湿地系统脱氮提供反硝化所需要的碳源,而且具有缓效持续释放的特点。添加此碳源材料可明显提高系统的脱氮效率,最高可提升30.85%,但随着C/N比的增加,硝态氮去除率逐渐降低,C/N比为3、5、8时分别为91.20%、87.72%和84.19%。添加碳源量达到C/N比为3时系统能够发生最大程度反硝化,此时不仅人工湿地系统脱氮效果得到提高,同时人工湿地除磷能力也有所增强。碱处理过的千屈菜材料在本系统中的最适宜添加量为5 g,即100 g/m2(C/N=3),远低于在进水中为满足反硝化所需调控的C/N比(5～8),可以节约外加碳源成本。     

固态碳源去除地下水硝酸盐的模拟实验

选取了5种研究较少的固体材料,棉花、丝瓜络、甘蔗渣、可降解餐盒、木屑作为去除地下水硝酸盐的外加碳源。在锥形瓶中进行反硝化对比实验,研究了不同固态碳源下NO3--N、NO2--N、NH4+-N及pH的变化情况,分析了NO3--N及总氮的去除率。研究结果表明,反硝化过程中pH呈升高趋势,在6.9～8.5范围内浮动。可降解餐盒和丝瓜络相对于其他的固态碳源来说,对NO3--N和总氮有较高的去除率,但丝瓜络的总氮去除率明显低于可降解餐盒。可降解餐盒的硝酸盐去除率达到98.28%,总氮去除率达到93.48%。可降解餐盒能够有效地去除地下水硝酸盐,达到以废治废的效果,是经济有效的最佳固态碳源。     

碳源对含盐废水短程硝化反硝化的影响

分别采用醋酸钠、甘油、乙醇和葡萄糖作为外加碳源,研究不同碳源对含盐废水短程硝化反硝化的影响.结果表明:(1)利用醋酸钠作为碳源,逐步增加NaCl盐度可以实现短程硝化反硝化,TN平均去除率高于95％.当NaCl盐度为14.2 g/L时,采用醋酸钠、甘油、乙醇和葡萄糖作为碳源时,NO2- -N的累积率分别为98.7％、86...     

Removal of added nitrate in the single, binary, and ternary systems of cotton burr compost, zerovalent iron, and sediment: Implications for groundwater nitrate remediation using permeable reactive barriers

Recent research has shown that carbonaceous solid materials and zerovalent iron (Fe(0)) may potentially be used as media in permeable reactive barriers (PRBs) to degrade groundwater nitrate via heterotrophic denitrification in the solid carbon system, and via abiotic reduction and autotrophic denitrification in the Fe(0) system. Questions arise as whether the more expensive Fe(0) is more effective than the less expensive carbonaceous solid materials for groundwater nitrate remediation, and whether there is any synergistic effect of mixing the two different types of materials. We carried out batch tests to study the nature and rates of removal of added nitrate in the suspensions of single, binary, and ternary systems of cotton burr compost, Peerless Fe(0), and a sediment low in organic carbon. Cotton burr compost acted as both organic carbon source and supporting material for the growth of indigenous denitrifiers. Batch tests showed that cotton burr compost alone removed added nitrate at a greater rate than did Peerless Fe(0) alone on an equal mass basis with a pseudo-first-order rate constant k=0.0830+/-0.0031 h(-1) for cotton burr compost and a k=0.00223+/-0.00022 h(-1) for Peerless Fe(0); cotton burr compost also removed added nitrate at a faster rate than did cotton burr compost mixed with Peerless Fe(0) and/or the sediment. Furthermore, there was no substantial accumulation of ammonium ions in the cotton burr compost system, in contrast to the systems containing Peerless Fe(0) in which ammonium ions persisted as major products of nitrate reduction. It is concluded that cotton burr compost alone may be used as an excellent denitrification medium in a PRB for groundwater nitrate removal. Further study is needed to evaluate performance of its field applications.     

高氨氮污泥脱水液短程硝化反硝化的启动及稳定

采用A/O-CSTR工艺处理高氨氮污泥脱水液。进水氨氮浓度浓度约为375 mg/L,C/N比小于1.0,反硝化碳源明显不足。A/O反应器完成短程硝化反应,CSTR定期投加初沉污泥作为碳源进行反硝化。两者联合达到总氮去除的目的。实验研究短程硝化反应的启动过程,以及CSTR出水回流对短程硝化和系统脱氮效果的影响。实验结果表明系统具有良好的硝化反硝化效果。A/O反应器亚硝酸盐积累率迅速提高并稳定在90%以上。CSTR有效利用初沉污泥实现了稳定的反硝化。出水回流有利于提高总氮去除率,在回流比为200%时,系统平均总氮去除率达到85%以上。     

矿物载体锯末碳源低温生物修复硝酸盐污染地下水

研究了低温条件下,沸石和火山岩为载体,锯末为碳源的生物反应器对地下水中硝酸盐氮的去除效果。结果表明,在（14±1）℃,水力停留时间18 h,进水硝酸盐氮浓度为27 mg/L的条件下,以锯末为碳源能有效去除地下水中的硝酸盐,沸石为载体时对硝酸盐氮的平均去除率为98%;火山岩为载体时对硝酸盐氮的平均去除率为95%。实验过程中出现铵盐和亚硝酸盐的积累,出水中氨氮浓度为1～2.55 mg/L,亚硝酸氮浓度为0～0.98 mg/L。出水pH均介于7～8,满足饮用水标准中pH的要求（6.5～8.5）。     

Process performance and polyphosphate-accumulating organism-glycogen-accumulating organism communities in an anaerobic/anoxic/oxic system operated with different carbon sources

A pilot plant anaerobic/anoxic/oxic (A2/O) system fed with domestic wastewater was operated to examine the effect of varying different types of carbon source (acetic acid, propionic acid, and glucose), added as a complement to the wastewater, on the (1) process performance and (2) microbial population. The operational condition that lead to a significant removal of total nitrogen (82%) was achieved with acetic acid. When the complementary carbon source was propionic acid, an improved removal efficiency of orthophosphate (97%) was observed. Because this finding was concurrent with higher polyphosphate-accumulating organism (PAO) population fractions detected using fluorescent in situ hybridization analysis (41.9 +/- 3.0%), it suggests that members of PAO populations that were able to reduce nitrate gained importance over PAO members that could not, thus improving the denitrifying phosphorus removal.     

Poly (ε-caprolactone) as substrate for water denitrification

In this paper, poly (ε-caprolactone) (PCL) was used as carbon source and biofilm supporter in a fixed bed bioreactor to biologically remove nitrate from drinking water. The experimental results showed that denitrifying microorganisms could easily adapt to PCL as carbon source and attach to the surface of PCL granules. The fine biofilm could form on the surface of PCL granules within 15 days. Denitrification rate was influenced by temperature greatly and it decreased sharply at low temperature (below 20°C) and it was strongly linearly correlated with influent DO level. The denitrification rate at DO 8.5 mg/L was 47.4% of the value at DO 1.4 mg/L. Fixed-bed bioreactor packed with PCL granules could remove 50 mg/L influent nitrate completely, but the effluent DOC and suspended matter level were high. Accordingly, post-treatment unit are needed to ensure the good quality of effluent. Nitrite level did not accumulate in the whole experiment. Microbial growth was the main reason for reactor clog.     

Effect of reactive media composition and co-contaminants on sulfur-based autotrophic denitrification

As a part of a study developing a biological reactive barrier system to treat nitrate-contaminated groundwater, the effects of reactive media composition and co-contaminants on sulfur-oxidizing autotrophic denitrification were investigated. The size of sulfur granules affected the denitrification rates; kinetic constants of 2.883, 2.949, and 0.677 mg-N(1/2)/L(1/2)/day were obtained when the granule sizes were below 2 mm, between 2 and 5 mm, and over 5 mm, respectively. When the volume ratios of sulfur to limestone were 1:1, 2:1, 3:1, and 4:1, kinetic constants of 5.490, 3.903, 4.072, and 2.984 mg-N(1/2)/L(1/2)/day were obtained, respectively. The presence of TCE up to 20 mg/L didn't significantly affect nitrate removal efficiency. At the TCE concentration of 80 mg/L, however, nitrate removal was markedly inhibited. Also, Zn and Cu inhibited the denitrification activity at more than 0.5 mg/L of concentration whereas Cr (VI) did not significantly affect the nitrate removal efficiency at all levels tested.     

Biological denitrification of drinking water using biodegradable polymer

The application of Biodegradable Polymer (BDPs), which can serve as biofilm carrier and simultaneously as water insoluble carbon source for heterotrophic denitrification. The external dosing of soluble organic substrate can be therefore avoided and process can be simplified as normal bio-filter. In this paper, the lab-scale experiment was carried out by using the cheap material of PBS, a new kind of commercial polymer polymerised by PCL and starch, and the results demonstrated that it was very efficient to eliminate nitrate. The PBS material performs the comparable non-sensitivity for the pH and DO value. The elevation of temperature within the range of 10-30°C can accelerate the process of denitrification. The BDPs bio-filter offers the favourable elimination of nitrate up to a total operation of 40 days.     

微氧膜生物反应器同时去除有机物和氮的研究

采用微氧颗粒污泥膜生物反应器处理生活污水,进行同时去除有机物和氮的研究。结果表明,膜出水COD不受水力停留时间变化的影响一直稳定在较低值,为15~35mg/L,去除率在94%以上。氮通过发生同时硝化反硝化反应而去除。在水力停留时间为16h以上时, 系统总氮去除率为65% ~92%,平均去除率为77%。     

A/O脱氮工艺的控制策略和应用性研究

根据A/O脱氮工艺的运行状况和影响因素 ,提出了应用在线传感器连续测定曝气池中DO浓度、氨氮浓度和硝酸氮浓度 ,并据此调节供氧强度、内循环回流量、有机碳源的投加以及硝化区和反硝化区的大小 ,这是保证A/O脱氮工艺良好处理效果的重要控制策略和思想。同时对近年来国外A/O脱氮工艺自动控制的应用及研究进行了简单的回顾。     

The effects of lake acidification on aquatic macrophytes--a review

Acidification of lakes results in a number of chemical, physical and biological changes. This review initially outlines the major floristic changes that occur in acidifying and limed lakes. The different types of evidence (historical comparisons, inter-lake comparisons and palaeoecological studies) are considered. These studies emphasise the replacement of calcicole species and others such as the isoetids with Juncus bulbosus and Sphagnun spp. in acidifying lakes. The review then discusses the way in which the various alterations in lake conditions affect the physiology of the macrophytes, particularly with changes in the availability of carbon, a change from nitrate to ammonium as a nitrogen source and the effects of an alteration in the Lake light climate. The population biology, community ecology and ecosystem functioning of macrophytes are discussed, especially where competitive processes may seem more important in determining community change than physiological processes. Particular consideration is paid to the types of evidence of floristic change that are useful and the importance of undertaking experimental studies at the correct scale to determine which factors may be causally related to the floristic evidence.     

太阳能光伏废水处理设施脱氮功能优化实例

某太阳能光伏企业的生产废水约4000 m³/d,废水中的主要污染物是少量的氟离子和大量硝态氮,原废水工艺中缺少去除硝态氮的功能。在原废水处理设施基础上,将生化处理工艺优化为“A/O反硝化”工艺,增加碳源投加设备。工程实践表明,工艺优化后,硝态氮得以有效去除,TN去除率达到95%,出水水质达到《电池工业污染物排放标准》(GB30484—2013)表2的间接标准。     

Simultaneous removal of nitrate and pentachlorophenol from simulated groundwater using a biodenitrification reactor packed with corncob

Both nitrate and pentachlorophenol (PCP) are familiar pollutants in aqueous environment. This research is focused on the simultaneous removal of nitrate and PCP from simulated contaminated groundwater using a laboratory-scale denitrification reactor packed with corncob as both carbon source and biofilm support. The reactor could be started up readily, and the removal efficiencies of nitrate and PCP reached up to approximately 98 % and 40–45 % when their initial concentrations were 50 mg N/L and 5 mg/L, respectively, after 15-day continuous operation at 10 h of hydraulic retention time (HRT) and 25 °C. Approximately 91 % of PCP removal efficiency was achieved, with 2.47 mg/L of chloride ion release at 24 h of HRT. Eighty-two percent of chlorine in PCP removed was ionized. The productions of 3-chlorophenol and phenol and chloride ion release indicate that the reductive dechlorination reaction is a major degradation pathway of PCP under the experimental conditions.     

电化学脱硝过程参数的响应曲面优化研究

以Ti/IrO2-TiO2-RuO2为阳极,Cu/Zn合金电极为阴极,在无隔膜电解池中对这一新构造电极对的脱硝氮性能进行了研究。为了有效结合阴极硝氮还原能力和阳极氧化能力,采用响应曲面法中的Box-Behnken设计优化了对电化学脱硝过程有显著影响的4个重要因素:氯化钠含量、电流密度、pH和初始硝氮浓度。优化结果表明,相对于pH和初始硝氮浓度,氯化钠含量和电流密度对脱硝性能影响更大,而阴极硝氮还原性能主要受初始硝氮浓度、pH的影响。以6 h内电极对脱氮百分率为响应量,优化得最佳电化学脱硝过程参数为:氯化钠含量,1 g/L;电流密度,24.99 mA/cm2;pH,1.81;初始硝氮浓度100 mg/L。在此实验条件下,6 h内电极对脱氮百分率预测值为99.84%。通过3次重复验证实验,确认实际6 h内电极对脱氮百分率为91.34%。预测值与实测值两者相差不大,由此可知,Box-Behnken设计是一种优化电化学脱氮实验参数的有效方法,经过优化后的电极对具有较佳的脱氮效率。