电极面积对无质子交换膜微生物燃料电池协同去污能力的影响

以间距是180μm的不锈钢网为电极,构建了单室型无质子交换膜微生物燃料电池(MFC)污水处理系统。分别驯化、培养厌氧消化菌和反硝化菌,厌氧消化菌在阳极附着成膜组成生物阳极氧化去除有机污染物,反硝化菌在阴极附着成膜组成生物阴极反硝化去除含氮污染物,研究了电极面积对污染物协同去除能力的影响。当电极面积为45 mm×100mm和45 mm×50 mm时,两系统的开路电压最大值分别为(182.8±6.2)mV和(161.8±5.4)mV,COD、NH4+-N和NO3--N最大去除率分别为96.5%、99.7%、99.7%和85.4%、92.2%、97.9%;出水中NO2--N的含量分别低于(0.072±0.006)mg/L和(0.084±0.008)mg/L。这表明电极面积大的系统具有较好的有机污染物和含氮污染物协同去除能力。     

厌氧氨氧化耦合异养反硝化的脱氮性能及污泥性状

通过连续实验和血清瓶批式实验研究了厌氧氨氧化耦合异养反硝化的代谢特性。在pH 7.8、温度25℃左右、水力停留时间1.5 h和苯酚浓度18.82 mg/L的条件下,耦合反应器能长期稳定运行。结果表明,NH+4-N、NO-2-N去除率高达100%,TN去除率为87.51%。消耗的NH+4-N、NO-2-N与生成的NO-3-N之比为1∶1.49∶0.12,平均总氮容积负荷为2.53 kg/(m3·d),平均总氮去除负荷可达2.26 kg/(m3·d)。系统内异养反硝化与厌氧氨氧化存在协同和竞争关系,总氮的去除是异养反硝化菌和厌氧氨氧化菌共同作用的结果。耦合系统中ANAMMOX对TN去除贡献率达到86.72%,异养反硝化对TN去除贡献率达到13.28%(其中以NO-2-N为电子受体的反硝化比例为7.16%,以NO-3-N为电子受体的反硝化比例为5.89%)。污泥性状研究表明,颗粒污泥存在3种形式:一种是ANAMMOX颗粒污泥;一种是苯酚反硝化颗粒污泥;一种是ANAMMOX菌外面包裹苯酚反硝化菌的颗粒污泥。另外,颗粒污泥的无机组分较高。污泥扫描电镜照片显示厌氧氨氧化菌为球状,反硝化菌为短杆状。     

厌氧氨氧化耦合部分反硝化处理低浓度氨氮废水

通过接种厌氧氨氧化菌(Candidatus Brocadia)与部分反硝化菌(Thauera)形成厌氧氨氧化与部分反硝化耦合处理模拟城镇污水中的氨氮(NH_4~+-N)与硝氮(NO3--N),考察不同NO3--N/NH_4~+-N比对耦合系统脱氮性能的影响及最佳NO3--N/NH_4~+-N比下耦合系统的稳定性和脱氮的途径。结果表明:在COD/NO3--N为2.5、NH_4~+-N浓度为20~40 mg·L~(-1)的条件下,NO3--N/NH_4~+-N比在0.8~1.6的范围内均可实现部分反硝化与厌氧氨氧化协同脱氮,且当NO3--N/NH_4~+-N比为1.2时,耦合效果最佳,对应的NH_4~+-N、NO3--N及总氮(TN)去除率分别为92.85%、99.68%和96.42%;厌氧氨氧化菌在耦合系统中的活性稳定在(4.62±0.44)mg·(g·h)-1(以VSS计),且与反硝化菌存在协同竞争关系,进水NO3--N的84.3%由厌氧氨氧化途径去除,15.7%由异养反硝化途径去除。     

UASBB-两段接触氧化处理规模化猪场废水的中试研究

研究了中试上流式厌氧污泥床生物膜反应器(UASBB)-两段生物接触氧化(BCO)处理规模化猪场废水工艺。结果表明,经过227 d运行,UASBB中成功地实现了同步厌氧氨氧化甲烷化反硝化;两段BCO经45 d成功地挂膜,并控制一段BCO池DO 1.4~1.8 mg/L,实现短程硝化积累NO-2-N;耦合UASBB和两段BCO,回流一段BCO的NO-2-N,确定最佳外回流比为300%;COD负荷达2.81 kg/(m3·d),中试系统对规模化猪场二级沼液、一级沼液、原水COD的去除率分别为94.7%、93%和96.9%,TN负荷达0.487 kg/(m3·d),去除率分别为84.1%、82.8%和84.7%,NH+4-N负荷达0.293 kg/(m3·d),去除率分别为92%、92.9%和88.5%;出水水质符合《畜禽养殖业污染物排放标准》(GB 18596-2001)。     

亚硝态氮对同时产甲烷反硝化工艺处理畜禽粪水的影响

为进一步提高同时产甲烷反硝化反应对畜禽粪水化学需氧量(COD)和氮的去除效率,应用畜禽粪水于接种颗粒污泥的厌氧混合式反应器,进行不同COD与亚硝态氮浓度比值(COD/NO-2-N)对同时产甲烷反硝化反应的影响研究。通过实时监测反应器内COD、凯氏氮(TKN)、辅酶F420、β-葡萄糖苷酶、产气率、pH和氧化还原电位(ORP)等指标得出,COD/NO-2-N为30/1、40/1时,COD去除率、辅酶F420和β-葡萄糖苷酶含量与空白无亚硝态氮的变化规律一致,亚硝态氮几乎未对糖类水解菌及产甲烷菌活性产生抑制作用;而COD/NO-2-N为10/1、20/1时,COD去除率、辅酶F420和β-葡萄糖苷酶含量较低,糖类水解菌及产甲烷菌活性受到抑制。     

污水中不同COD组分下A/O脱氮工艺的反硝化效率

为了研究了不同COD组分进水对A/O工艺中反硝化的影响以及COD组分中溶解性易生物降解COD(SS)、颗粒性慢速可生物降解COD(XS)比例改变后系统反硝化速率和反硝化潜力的变化。以连续流A/O反应器脱氮效率为研究对象,通过改变碳源物质投配量来配置3种SS比例分别为15%、30%和50%的城市污水,系统地考察了进水中SS比例对反硝化的影响。结果表明,进水中SS比例由15%增加到50%后,可以明显提高A/O系统TN的去除率,脱氮率由82%提高到89%。同时通过缺氧反硝化间歇实验,从反硝化动力学角度分析,进一步确定进水中SS比例对反硝化速率和反硝化潜力的影响,发现进水SS比例分别为50%、30%和15%,系统反硝化速率分别为0.027 g NO-3-N/(g VSS·min)、0.022 g NO-3-N/(g VSS·min)和0.020 g NO-3-N/(g VSS·min),反硝化潜力分别为16.49、13.99和13.74 mg/L。可见随着进水中SS比例的升高,系统中反硝化速率和反硝化潜力也相应增加。得出进水中COD组分不同,尤其是SS所占比例大小,是影响反硝化效果的一个关键因素。     

“生态沟渠+人工湿地”系统处理农田退水中噻虫嗪

研究了不同水力停留时间(HRT)和农药污染负荷(PPL)下,"生态沟渠+水平流人工湿地"和"生态沟渠+垂直流人工湿地"系统对农田退水中常规污染物和噻虫嗪的去除效果。结果表明,"生态沟渠+垂直流人工湿地"系统对COD、NH+4-N、NO-3-N、TN、TP及噻虫嗪的去除率均优于"生态沟渠+水平流人工湿地"系统,分别为76%、97%、92%、95%、88%和40%(HRT=2 d),其中噻虫嗪在沟渠段的去除率为17%,在垂直流人工湿地段的去除率为23%。延长HRT、降低PPL均有利于噻虫嗪在组合系统中的去除。对垂直流人工湿地各基质层出水噻虫嗪浓度检测结果表明,运行前期,噻虫嗪在空心砖层去除率最高(8%),主要是由于空心砖对于噻虫嗪的吸附优于沸石和钢渣,随着系统运行,土壤+细沸石层和粗沸石层的去除效率增加,植物吸收与微生物降解作用逐渐占据主导地位。微生物群落结构分析结果显示,生态沟渠段β-变形菌纲和厌氧绳菌纲丰度分别为11%和10%。垂直流人工湿地自上而下芽孢杆菌逐渐增多成为优势菌,β-变形菌和厌氧绳菌逐渐减少。厌氧、好氧交替环境有利于常规污染物和噻虫嗪的去除。     

前置反硝化生物滤池深度脱氮效能与影响因素

前置反硝化生物滤池具有良好的脱氮性能,被广泛用于污水的深度处理。采用该工艺对城市污水处理厂尾水进行深度处理,通过调节硝化液回流比(50%、100%、150%)和水力负荷(1.0、1.5和2.0 m~3·(m~2·h)-1),考察前置反硝化生物滤池工艺对COD、TN、NH+4-N的去除效果。结果表明,当硝化液回流比为100%时,系统对污染物去除效果最好。在进水COD、TN、NH+4-N平均浓度为120、35和15 mg·L~(-1)的水质条件下,出水COD、TN、NH+4-N平均浓度可降到7.62、5.02和0.60 mg·L~(-1),去除率分别为93.65%、85.65%和96.00%。在水力负荷为1.5 m~3·(m~2·h)-1条件下,系统对COD、TN和NH+4-N的平均去除率达到了83.00%、90.14%和95.73%,出水可以达到《城镇污水处理厂污染物排放标准》(GB 18918-2002)一级A标准。     

多级潮汐流人工湿地对污泥厌氧消化液中氨氮及有机物的去除特征

针对城市污水处理厂污泥厌氧消化液回流而引起城市污水处理厂处理系统内氨氮累积的问题,采用多级潮汐流人工湿地(MTF-CWs),研究MTF-CWs对污泥厌氧消化液中氨氮和有机物的去除特征及其主要去除途径。经过260 d的运行,结果表明,NH_4~+-N和COD平均进水浓度分别为859.55 mg·L~(-1)和446.52 mg·L~(-1),MTF-CWs对NH_4~+-N和COD均有较好的处理效果,平均去除率分别为66.50%和47.10%。在MTF-CWs中,转化为NO_2~--N和NO_3~--N占被去除NH_4~+-N的73.21%,硝化反应是NH_4~+-N去除的主要途径,MTF-CWs的平均硝化速率为0.3 kg·(m~3·d)~(-1)。TN的平均去除率为17.63%,去除效果较差,其原因在于原水中缺少反硝化所需要的碳源。     

焦化废水特征有机污染物反硝化降解速率特征分析

以焦化废水特征有机污染物苯酚、喹啉、吡啶和吲哚为碳源,研究了不同C/N(COD/NO-3-N)比值进水条件下,反硝化过程中NO-2-N积累特征及反硝化动力学特征。结果表明,进水C/N比在2.5~17的条件下,均会出现NO-2-N积累的现象。当C/N比值为2.5时,NO-2-N出现稳定积累。基于完全反硝化且COD去除率最高的进水条件为,进水C/N比为6。随着C/N比值从2.5增至17,达到NO-2-N的最大积累量时间从140 min降至60 min,NO-2-N的最大积累率从51.7%降至23.1%。相同进水C/N比条件下,在NO-2-N积累阶段,NO-3-N比还原速率大于NO-2-N比还原速率,导致NO-2-N积累;在NO-2-N还原阶段,NO-3-N比还原速率小于NO-2-N比还原速率。不同进水C/N比条件下,在NO-2-N积累阶段,NO-2-N比积累速率基本不变,为0.072 g N/(g VSS·d)左右。不同进水C/N比值条件下,NO-2-N积累阶段的表观碳氮比均大于NO-2-N还原阶段的表观碳氮比。     

Optimization of Height of Release of Air Pollutants

A number of key projects in the Environmental Protection Agency (EPA) particulate R&;D program having applicability to industry are presented. For electrostatic precipitators (ESP) there is presented the result of work on large diameter discharge electrodes which provide a decrease in penetration of up to a factor of 4 when compared to conventional small diameter electrodes. Also discussed is the multistage ESP which provides a collection efficiency that would require a collecting plate area 4 or 5 times larger with conventional ESP technology. The E-SOX technology makes use of the multistage concept to free up space in the ESP for SO₂ removals of up to 90%. Electrostatically augmented fabric filtration provides a reduction in pressure drop of about 5 0% as compared to conventional fabric filtration. Wind tunnel modeling of windbreaks for material storage piles indicates a potential for providing engineering design data that would allow significant emission reduction caused by wind erosion     

Investigation of the characteristics of the reflectivity of clouds

This paper investigates some of the reflectivity characteristics that clouds (when modelled as solid bodies) must exhibit to be compatible with observations that the reflecting surface of a cloud (i) appears almost equally bright across its face, (ii) is brightest when the cloud is opposite to the Sun but decreases in brightness as the cloud moves to other positions and (iii) increases in brightness with increasing optical thickness of the cloud in the observer's line of sight. These observations, respectively, are shown to imply that the peak value of the bidirectional total reflectivity from a cloud surface (i) increases in inverse proportion to the cosine of the angle between the Sun and the normal to the cloud surface, as the incident angle increases, (ii) appears to be directed back in the direction of the incident radiation, and (iii) increases as optical thickness of the cloud in the observer's line of sight increases. The results could have application in many fields (e.g. modelling diffuse radiance distributions for cloudy skies).     

实验室质量管理体系内部审核的实施

在实施ISO／IEC17025：1999标准《检测和校准实验室能力的通用要求》过程中，通过实验室质量管理体系内部审核的实践与系统分析，识别出内部审核实施阶段的关键环节，提出召开首次会议、收集审核证据、确定审核发现和召开末次会议的技术方法，对提高内部审核的质量和有效性、获得可靠的审核结论具有重要意义。     

Estimation of uncertainty of sampling for analysis of pesticide residues

Abstract

A computer model was used to take random samples from primary sample populations obtained from field trials to simulate the uncertainty of sampling for residue analysis of plant commodities and soil. The results indicate about 40%, 30% and 20% relative uncertainty when random samples of size 5, 10 and 25 are taken respectively, from a single lot. Therefore the sample size should be the same for establishing and enforcing legal limits.     

扬中生态环境建设的思考与实践

结合扬中生态环境的基本情况和存在的不足，进行了具体分析，对扬中未来生态建设的发展方向提出了建议及实施措施。     

An application of the theory of kinematics of mixing to the study of tropospheric dispersion

The most common technique used for numerical simulations of tracer mixing is that of the numerical solution of the advection–diffusion equation with the unresolved fluxes parameterized using the similarity theory. Despite correct predictions of the overall directions of transport, models based on a numerical solution of the advection–diffusion equation lack sufficient accuracy to correctly reproduce the coupling of mixing with small scale processes which are sensitive to the microstructure of the tracer distribution. The objective of this paper is to revisit the basic formalism employed in numerical models used to investigate atmospheric tracers. The main mathematical method proposed here is the theory of kinematics of mixing which could be applied effectively for simulations of atmospheric transport processes. At the beginning of the paper, we introduce simple mathematical transformations in order to demonstrate how complex topological structures are created by mixing processes. These idealistic flow systems are essential to explain transport properties of much more complex three-dimensional geophysical flows. An example of the application of the kinematics of mixing to the analysis of tracer transport on a planetary scale is presented in the following sections. The complex filamentary structures simulated in the numerical experiment are evaluated using some commonly applied statistical measures in order to compare the results with the data published in the literature. The results of the experiment are also analysed with the help of simple conceptual models of fluid filaments. The microstructure of the tracer distribution introduced in the paper is essential to increase our understanding of atmospheric transport and to develop more realistic parameterizations of small-scale mixing. The presented results could also be used to improve calculations of the coupling between microphysical processes and tracer mixing.     

次氯酸钠发生器的研制

介绍了电解法生产次氯酸钠的原理 ,并在原有生产工艺的基础上进行了重新设计和对设备的重新选择、改造 ,得出了各个工艺参数的最佳值 ,生产出高品质的次氯酸钠     

Comparison of methods for evaluation of activity of photocatalytic films

Objective

This work aims to investigate the correlation between the photocatalytic activity determined by methylene blue bleaching (DIN 52980), stearic acid degradation, and degradation of acetone in gas phase.

Method

The photocatalytic TiO₂ coatings included in this investigation ranged from thin commercially available coatings (Activ^TM and BioClean^TM) and ready to use suspensions (Nano-X PK1245) to lab-produced PVD and sol?Cgel coatings. XRD analysis of the photocatalytic coatings showed that all the coatings consisted of nanocrystalline anatase, although the thickness and porosity varied considerably.

Results

The study showed that the reproducibility of the activity measurements was good. However, more importantly, the investigation showed that there is a good correlation between the activities determined by the different methods even though the characteristics of the photocatalytic coatings and the organic probe molecules varied considerably.

Conclusion

The overall findings of this work suggest that there is a good correlation between the investigated methods. These results are promising for the future work concerning standardization of methods for determination of the activity of photocatalytic films.     

Impact of overexploitation of shellfish: northeastern coast of India

India has a very extensive coastline of about 7515 km, rich in diverse living resources. These resources continue to deteriorate with rampant harvesting or are altered for other uses such as aquaculture and fisheries. The present paper deals with degrading coastal habitats in northeastern India, and projects the intensity of the stress arising from the collection of tiger prawn seeds (Penaeus monodon) for aquacultural farms and molluskan shells for poultry feed and edible lime. Indiscriminate exploitation of these resources leads to a heavy reduction of the species concerned and other associated marine communities. The magnitude of such destruction has been quantified. The impacts of biodiversity loss and their after-effects on the ecobalance of this coastal system have become a matter of great concern to ecologists to maintain security and sustainability. The authors propose a public awareness program on themes relating to the importance of biodiversity for human livelihoods.