粉末活性炭-超滤组合工艺对二级出水中污染物的去除及膜污染机制研究

采用粉末活性炭(PAC)-超滤(UF)组合工艺处理污水处理厂二级出水,探讨不同PAC投加量下PAC-UF组合工艺对溶解性有机物(DOC)及抗生素抗性基因(ARGs)的去除效果,分析PAC对UF膜污染的缓解机制。结果表明,与直接UF相比,PAC-UF组合工艺可有效降低出水DOC和ARGs含量;水中4种ARGs与微生物含量、整合子intI1、DOC浓度间呈显著相关关系,说明去除上述指标有助于削减不同类型ARGs;PAC可吸附水中小分子量有机物,提高膜比通量,改善UF膜的反冲洗效果,PAC投加量为20mg/L时效果最好;PAC投加量增加可使滤饼层变得致密,使UF膜的不可逆污染阻力下降,但总污染阻力增加;直接UF与PAC-UF组合工艺的膜污染主导机制均为滤饼层污染,其中PAC-UF组合工艺受滤饼层污染机制影响更大。综合考虑污染物去除及膜污染缓解效果,采用低投加量(20mg/L)的PAC-UF组合工艺处理二级出水最为适宜。     

PACT工艺处理PAM生产废水的实验研究

采用粉末活性炭活性污泥工艺(PACT)处理经凹凸棒土预处理后的聚丙烯酰胺(PAM)生产废水。实验考察了粉末活性炭(PAC)的投加对活性污泥处理系统的影响,并探讨了PAC投加量、曝气时间、水力停留时间等参数对降解反应的影响。结果表明:PAC的投加能提高水中溶解氧的利用率,改善污泥沉降性能,增强活性污泥系统对有机物的去除效果;在PAC投加量500 mg/L、曝气10 h的条件下,PACT工艺对PAM生产废水的处理效果良好,COD的去除率为80.8%,BOD5去除率为83.8%,丙烯酰胺(AM)去除率为84.2%。     

芬顿试剂氧化-PAC吸附工艺处理电厂排污水

开发了芬顿试剂预氧化-粉末活性炭(PAC)吸附组合工艺处理电厂循环冷却排污水。首先分别研究了芬顿试剂氧化法和粉末活性炭吸附法对有机物的去除效果,发现2种工艺在最佳处理条件时仍存在处理效果较差、药剂费用高等问题。因此,开发了芬顿试剂预氧化-PAC吸附组合工艺,研究了该工艺的影响因素,并进行小试实验。结果表明,该组合工艺在不改变原水的初始pH、H_2O_2与Fe~(2+)的摩尔比为1以及H_2O_2的投加浓度为25 mg·L~(-1)时得到最佳的预处理条件。在最佳预氧化条件下投加0.15 g·L~(-1)的PAC进行了4级逆流吸附小试实验,结果表明:该工艺处理效果稳定、药剂费用低,出水满足排放要求。     

强化混凝法处理微污染窖水的试验研究

研究了使用单混凝剂聚合氯化铝(PAC)混凝、助凝剂阴离子型聚丙烯酰胺(APAM)-PAC复配混凝和粉末活性炭联合APAM-PAC强化混凝对窖水的处理效果。结果表明,在PAC质量浓度为15.0mg/L,APAM质量浓度为0.15mg/L,粉末活性炭投加量为20mg/L的强化混凝条件下,微污染窖水中的UV_(254)、COD和浊度的去除率可分别达到66%、54%、97%。APAM对有机物的去除效果提升没有分子量选择性,而粉末活性炭对小分子有机物的去除效果更为明显。     

聚合氯化铝与粉末活性炭联合强化混凝处理垃圾渗滤液

研究了联合粉末活性炭与聚合氯化铝(PAC)强化混凝对垃圾渗滤液原水的处理效果。结果表明,在原水COD为4 100 mg/L、浊度为147 NTU、UV254为20的条件下,粉末活性炭的加入可以有效增加垃圾渗滤液中有机物的去除率,PAC投加量为0.6 g/L时,投加0.6 g/L粉末活性炭,COD的去除率由21.6%提高到29.1%,UV254去除率由29.8%提高到39.9%,剩余浊度由138 NTU降到133 NTU。该强化混凝过程使原水中溶解性小分子有机物的去除率提高显著,PAC投加量为0.6 g/L时,投加0.6 g/L粉末活性炭,在分子量小于1 kDa的范围内,UV254去除率由2.9%上升为10%。     

粉末活性炭对膜过滤性能的影响

向一体式膜生物反应器中投加粉末活性炭(PAC),可以显著提高膜的过滤性能,有效缓解膜的污染.研究结果表明:投加PAC的吸附作用减少了由于胞外聚合物(EPS)而引起的膜污染;膜表面PAC颗粒的存在减小了浓差极化层的厚度和水力边界层的厚度,提高了过滤物质的传递速率;膜表面形成的PAC层还可过滤微生物和胶体颗粒,减少了它们到达膜表面的数量.     

PAC/AC吸附对超滤膜去除再生水中有机物影响

研究了粉状活性炭(PAC)和活性焦(AC)吸附对超滤膜(UF)去除再生水中有机物的效能及其对膜污染的影响。结果表明,PAC和AC吸附预处理可有效改善超滤膜出水水质,投量为40 mg/L时,PAC和AC单独吸附对DOC去除率分别为40.2%和32.6%,超滤出水DOC去除率则由直接膜滤时的21.4%提高至47.2%。UF对大于10 k Da的大分子有机物有较好的截留能力,PAC较AC对中小分子有机物的吸附效果更好。三维荧光(3D-EEM)分析显示,原水中溶解性微生物代谢产物和腐殖质类有机物所占比重较大;直接UF对溶解性微生物代谢产物的去除能力较好,投加PAC和AC促进了紫外腐殖酸和类腐殖酸类有机物去除,紫外腐殖酸EEM峰值分别下降51.7%和48.8%,类腐殖酸EEM峰值下降63.0%和59.9%。投加PAC和AC并经0.45μm膜预过滤可提高超滤膜通量,其在过滤周期内的下降率由直接膜滤时的27.6%分别降至23.5%和24.4%。AC较PAC更为经济,AC-UF可替代PAC-UF作为经济可行的再生水深度净化工艺。     

造纸中段废水的混凝-臭氧氧化深度处理研究

就混凝-臭氧氧化组合工艺对造纸中段废水生物处理出水的净化效果进行了研究.结果表明,Ca(OH)2对废水色度、TOC、COD和254 nm的紫外吸收值(UV254)的去除效果均优于聚合氯化铝/聚丙烯酰胺(PAC/PAM);Ca(OH)2-O3组合工艺的处理效果也优于PAC/PAM-O3工艺.当Ca(OH)2投加量为1 g/L、臭氧投加量为50 mg/L时,废水色度降低至10倍以下,COD小于150 mg/L.经Ca(OH)2混凝处理后,相对分子量在0.5～1.0 ku和10.0 ku以上的有机物显著减少;进一步臭氧氧化处理后,除0.5 ～1.0 ku范围的有机物大幅度增加外,其余分子量有机物显著减少.由于对色度贡献很大的大分子量物质的去除,废水的色度显著下降直至无色.     

应对南方某水厂土霉嗅味的活性炭技术

粉末活性炭(PAC)是应对季节性嗅味问题的主要处理技术,选择合适的活性炭、确定投加条件等因素对于水厂的高效运行等具有重要意义。针对南方某水厂存在的季节性嗅味问题,选择了国内9种常用PAC(包括3种煤质炭,3种木质炭,3种椰壳炭),对其吸附能力及处理成本进行比较,同时对该水厂在用PAC的处理效果、原有预氧化工艺(预加次氯酸钠及高锰酸钾)的影响等条件进行评价。结果表明:9种PAC中碘值为1 030mg·g~(-1)的椰壳炭吸附能力最强,对150 ng·L~(-1)的2-甲基异崁醇(2-MIB)吸附容量为6.2 ng·mg~(-1)。水厂的预氧化工艺会显著降低PAC对2-MIB、土臭素(GSM)的吸附效果(分别降低29.5%、31.6%)。综合处理效果和经济成本后,碘值为800 mg·g~(-1)的煤质炭对该水厂水源条件下的嗅味问题处理效果最优,在将2-MIB浓度由150 ng·L~(-1)处理至嗅阈值以下时,水的活性炭处理成本为0.3元·t~(-1)。     

碳基材料对污水厂尾水和太湖水体中CDOM的吸附特征

采用颗粒活性炭、粉末活性炭和碳纳米管3种典型碳基材料来吸附太湖水和污水厂尾水中的有机物,考察碳基材料对水中有色可溶性有机物(CDOM)的吸附特征。基于荧光光谱和平行因子分析(PARAFAC),提取出C1(腐殖酸类)、C2(色氨酸类蛋白)和C3(酪氨酸类蛋白)3个PARAFAC荧光组分。粉末活性炭和碳纳米管具有发达的中孔孔隙结构,对水中大分子有机物具有较高的吸附容量,颗粒活性炭微孔结构发达反而不利于吸附水中腐殖酸等大分子有机物。粉末活性炭对水中有机物具有最高的吸附速率,对太湖水中荧光组分C1、C2和C3的吸附速率分别为0.278、0.358和0.359min-1,颗粒活性炭的吸附速率明显低于粉末活性炭和碳纳米管。研究结果揭示了水中复杂混合有机物的吸附特征,为吸附工艺参数的优化提供技术参考。     

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.