钙离子对混凝去除水体中铜绿微囊藻的影响

以铜绿微囊藻为对象,研究了钙离子对聚合氯化铝(polyaluminumchloride,PAC)混凝沉淀藻细胞的影响及其可能的机理。结果表明,添加钙离子对PAC混凝去除模拟水样藻细胞和浊度均具有促进作用。在PAC摩尔浓度较低时(0.02 mmol·L~(-1)),最高可将除藻率和除浊率分别提高66.4%和76.8%。三维荧光及总溶解性有机碳(total(dissolved organirc carbon,TDOC)分析表明钙离子对去除水中溶解性胞外有机物(dissolved extracellular organic matter,dEOM)没有显著作用。利用Zeta电位和絮体形态对其影响混凝除藻效果的可能机理进行探究,发现钙离子能通过压缩双电层和吸附电中和提高藻细胞表面的Zeta电位,从而促进胶体脱稳凝聚。推测钙离子通过与铜绿微囊藻表面的黏附型胞外有机物(bound extracellular organic matter,bEOM)发生阳离子架桥作用促进藻细胞脱稳混凝沉淀。钙离子能够促进铜绿微囊藻脱稳,但是絮体粒径、强度、恢复能力的主要影响因素还是PAC摩尔浓度。     

水样pH对不同碱度含藻水混凝性能的影响

为探明碱度对混凝去除藻细胞及其分泌有机物的影响,保证饮用水水质.以铜绿微囊藻为研究对象,选用氯化铝(A1C13·6H2O)作为混凝剂进行混凝实验,考察了不同碱度的含藻水样在pH为6.0～9.0条件下的混凝性能、絮体特性和出水余铝.结果表明:当水样pH=6.0时,相对于低碱度(95、175和245 mg·L-1)水样,碱...     

臭氧对混凝剂形态及功能的影响

应用Ferron逐时络合比色法,从铝形态分布及其转化的角度,研究了臭氧对聚合氯化铝混凝性能影响并探究其原因。结果表明,预臭氧对聚合氯化铝(PAC)的混凝效果有显著影响。在一定质量浓度范围内(0~3.60mg/L),臭氧浓度越高,水样浊度越高(其UV254(即254nm波长下水样的紫外吸光度值,表征含芳香环结构和共轭双键结构的有机物含量)和溶解性有机碳(DOC)的去除效果较显著)。臭氧对混凝剂水解形态有显著影响。预臭氧后,混凝絮体形成和浊度的去除与铝混凝剂中中等聚合态铝(Alb)的含量有关,Alb的含量越高,浊度去除效果越好。因此,臭氧剂量的增加抑制Alb生成可能是导致浊度升高的一个重要原因。     

高锰酸钾对藻细胞及胞外有机物的控制效果

以假鱼腥藻(Pseudoanabaena sp.)和颤藻(Oscillatoria sp.)等蓝藻(Cyanobacteria sp.)为优势藻群的深圳石岩水库水样为对象,研究高锰酸钾在氧化过程中藻细胞活性、胞外有机物DOC浓度、胞外溶解性有机物(DOM)的荧光特性变化,以及高锰酸钾预氧化强化混凝除藻和去除有机物的效果。在荧光显微镜下观察到,低浓度(0~1.5 mg·L~(-1))高锰酸钾对藻细胞的灭杀效果并不明显。较高浓度(5 mg·L~(-1))高锰酸钾则对藻细胞结构有一定程度的破坏,藻细胞的总数减少了28%。研究发现,高锰酸钾能够氧化藻细胞使其释放胞内物质,投加1.5mg·L~(-1)后胞外2-甲基异莰醇(2-MIB)与土臭素(GSM)浓度均有所升高。在高锰酸钾氧化过程中,胞外DOC和DOM荧光总量随氧化时间的延长均呈降低-升高-降低的趋势;5 mg·L~(-1)的高锰酸钾氧化10 min时就会引起芳香性蛋白质类物质和溶解性微生物代谢产物类物质的升高。高锰酸钾能够有效强化混凝去除藻类和有机物,聚合氯化铝(PAC)最优投加量为3 mg·L~(-1),高锰酸钾最优投加量为0.6 mg·L~(-1)。     

不同混凝剂处理低温低浊水

针对低温低浊水处理难度大的问题进行了一系列的混凝实验,实验结果表明,随着混凝剂投加量的增加,剩余浊度呈现先降低后升高的趋势,单独使用HPAC时,剩余浊度在投加量为14 mg/L时达到最低(2.39 NTU)。pH值对余铝含量具有重要的影响,3种铝系混凝剂均在pH=7.0时余铝含量达到最低。Al Cl3对水中有机物的去除率较其他3种混凝剂低。絮体形成与破碎受搅拌强度的影响很大,当破碎强度增加到50 r/min,使用PACl、HPAC、Fe Cl3作混凝剂时絮体粒径下降不明显,当破碎强度增加到100 r/min时,絮体粒径有明显的下降。破碎结束后,絮体粒径有所恢复,但是并不能增长到破碎前的粒径。PACl、HPAC以及Fe Cl3形成的絮体的沉降性较好,上覆水浊度下降较快,经过3 h的沉降后,剩余浊度分别达到1.82、1.44和0.97 NTU。     

优化混凝处理低温低浊黄河水及对余铝的控制

考察了4种混凝剂,高效聚合氯化铝（HPAC）,聚合氯化铝（PACl）,硫酸铝（Al2（SO4）3）,混合PACl和氯化铁（FeCl3）,对低温低浊黄河原水的混凝效果与沉后水残留铝含量的关系。结果表明,当采用Al2（SO4）3或PACl做混凝剂时,在取得较好浊度去除的投药量下,水中余铝浓度会超过国家标准（0．2131g／L）。而采用HPAC或FeCl3和PACl复配药剂,在取得与Al2（SO4）3或PACl类似的浊度去除效果的同时,也能较好地控制水中的余铝含量。当HPAC投加量为21mg／L时,沉后水浊度降至1．3NTU,残留铝含量为0．147mg／L。复配投加PACl 15mg／L和FeCl3 12mg／L后,沉后水浊度为1．18NTU,残留铝含量为0．074mg／L。PACl和氯化铁的复配比例需要精确的调控,否则容易导致出水余铁余铝含量增加。而HPAC投加量小于21mtg／L时出水余铝浓度均低于国家标准。因此,在这4种混凝剂中,就混凝效果及余铝控制而言,HPAC更适合充当低温低浊水源水的混凝处理药剂。     

PAM复配混凝剂对高岭土体系混凝过程的影响

为了解决无机混凝剂在混凝过程中的不足选用AlCl_3及其与2种不同阴离子度的PAM复配的混凝剂对高岭土体系进行混凝实验研究。结果表明:使用AlCl_3做混凝剂,当投加量(以Al计)为0.1 mmol·L~(-1)时,剩余浊度达到最低;平衡时粒径达到700μm且随着破碎时间的延长,絮体再生长结束后的粒径逐渐减小在破碎时间为6.O min时,絮体粒径最终能恢复到300左右。以PAM4复配的AlCl_3为混凝剂在投加量为0.1 mmol·L~(-1)时,剩余浊度最低;经慢速搅拌10 min絮体平衡时的粒径较使用AlCl_3作混凝剂时略小,但随着PAM4浓度的増大,絮体破碎后的恢复能力逐渐増大。当PAM4与Al的比例为10%破碎1.0 min时絮体粒径最终可以恢复到600μm左右。以PAM-2复配的AlCl_3为混凝剂时,由于PAM-2的阴离子度过高需要更多的混凝剂中和体系中存在的负电荷,所以在混凝剂浓度为0.2 mmol·L~(-1)时,剩余浊度才达到最低。     

不同混凝剂处理松花江低温水

东北松花江地区冬季有将近6个月的冰封期,低温季节水源水处理难度大。为了保证东北地区冬季饮用水供应,研究几种混凝剂在处理冬季松花江低温水时的混凝效果。实验结果表明,NPAC1和NPAC2水解产物中具有较高的Alb和Alc成分,拥有较高的电中和、吸附和网捕卷扫性能,高效聚铝铁(PAF)水解产物Fe(OH)3具有比表面积大、吸附架桥作用较强的优点。这3种混凝剂无论是在控制出水浊度还是在对水体有机物去除能力方面均优于目前水厂所使用的PAC和聚合氯化铝铁(水厂PAF);NPAC2的投加量达到50 mg/L时,出水浊度达到最优;当混凝剂投加量达到50 mg/L时,NPAC1的浊度去除率逐渐超过NPAC2,剩余浊度低于3.0 NTU;NPAC1、NPAC2和PAF 3种混凝剂对有机物的去除能力大致相当,当混凝剂投加量为50 mg/L时,这3种混凝剂处理后的水的UV254的值均低于0.06,而水厂使用的2种混凝剂处理后的水的UV254仍高于0.1;结合其对浊度去除的情况,可以判断55 mg/L的投药量为NPAC1的最优投药点,PAF的最佳投药量为65 mg/L;投加适量的粉末活性碳可以有效地提高氨氮的去除率,当粉末活性炭的投加量为30 mg/L时,氨氮的去除率基本达到最大(51.27%)。表面负荷对混凝效果具有重要的影响,合理降低沉淀池的表面负荷对于提高出水水质具有重要作用。     

可用于去除高盐废水中有机污染物的混凝-Fenton氧化联合工艺

以某环氧树脂生产厂产生的高盐有机废水为对象,对比研究了Fenton、Fenton-混凝、混凝-Fenton等工艺去除废水中有机污染物的效能。考察了Fenton反应中Fe2+、H2O_2投加比、初始pH、反应时间以及混凝反应中混凝剂种类、投加量等参数对处理效果的影响。结果表明:Fenton工艺的最佳条件为亚铁和过氧化氢投加比1∶20,投加量分别为25 mmol·L~(-1)和500 mmol·L~(-1),初始pH 3,反应时间120 min,TOC去除率为62.50%;混凝工艺选择Fe SO_4混凝剂,投加量为300 mg·L~(-1),TOC去除率为23.78%;废水经过Fenton-无混凝剂混凝、Fenton-混凝剂混凝、混凝-一级Fenton氧化和混凝-二级Fenton氧化工艺处理,TOC去除率分别为68.32%、71.51%、80.69%和89.27%。     

天然橄榄石对水体铜绿微囊藻的去除效果

为开发安全、高效、廉价的水华控制技术,选择铝土矿、磷铁矿、黄铁矿、铬铁矿及橄榄石等10种天然矿物材料,以水体铜绿微囊藻为研究对象,通过跟踪测定其叶绿素a的变化,研究了天然矿物对水体铜绿微囊藻去除特性,并探讨了天然橄榄石去除铜绿微囊藻的影响因素及去除机理。结果表明:相同条件下天然橄榄石具有最高的除藻能力;矿物用量及藻密度对橄榄石除藻过程影响最大,其次为pH及水温,光强影响最小;当橄榄石浓度为1.5 g·L-1,藻密度1.7×106 cells·mL-1、水温15℃、反应介质为弱酸性或中性(pH 5～7)时,吸附1 h后,叶绿素a去除率高于96%。进一步分析可知,天然橄榄石主要通过静电作用对铜绿微囊藻进行吸附,进而使藻细胞絮凝沉降,部分藻细胞破裂分解,同时天然橄榄石在反应过程中吸附培养基中的营养盐,造成藻细胞营养缺少,从而对藻细胞的生长造成一定的抑制作用。     

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.