氨氮浓度对马铃薯加工废水厌氧消化的影响

为考察氨氮浓度对中温厌氧消化处理马铃薯加工废水的影响,通过批式实验,探究该类废水厌氧消化处理的氨氮抑制阈值。结果表明：氨氮浓度为3 000 mg·L⁻¹ (TAN≈3 659 mg·L⁻¹)时,累积产甲烷量降低至276.1 mL·g⁻¹且出现产甲烷迟滞期;氨氮浓度为4 000 mg·L⁻¹ (TAN≈4 468 mg·L⁻¹)时,累积产甲烷量仅为对照组的39.2%,迟滞期明显延长了7.2 d;高浓度氨氮抑制造成了以丙酸为主的VFAs积累和有机物(蛋白质等)降解不完全,这是COD去除率下降的主要原因;VFAs作为氨氮抑制发生时COD的主要组分,其积累可作为马铃薯加工废水厌氧消化过程发生氨氮抑制的指示因子;马铃薯加工废水中温厌氧消化的氨氮阈值约为3 000 mg·L⁻¹。该结果可为马铃薯加工废水的高效处理与资源化利用提供参考。     

氨氮浓度对猪粪厌氧消化及产甲烷菌群结构的影响

氨氮抑制是影响高含固厌氧消化推广应用的主要因素之一。通过批式实验,采用外源氨氮投加方式,考察了厌氧消化过程中不同氨氮浓度对鲜猪粪产甲烷效果和产甲烷菌群结构的影响。结果表明：氨氮添加量为2 000 mg·L-1（TAN≈3 596.7 mg·L-1）时,日产甲烷速率及累积产甲烷量均明显下降;添加量大于4 000 mg·L-1（TAN≈5 618.7 mg·L-1）时,氨氮抑制加剧,出现VFAs累积、产甲烷高峰期后移、丙酸降解失败。不同氨氮投加量下猪粪中挥发性固体（VS）产甲烷率分别为（369.0 ± 17.3）、（318.5 ± 7.6）、（234.7 ± 2.5）、（165.4 ± 19.4）mL·g-1,产甲烷效率较对照组分别下降14%、36%和55%。超过4 000 mg·L-1的外源氨氮投加促使产甲烷菌群结构发生显著变化,乙酸利用型产甲烷优势菌Methanosaeta 逐渐被Methanosarcina代替,而氢利用型产甲烷菌属中Methanospirillum的优势性逐渐被Methanoculleus和Methanomassiliicoccus取代,说明后者均有较强的氨氮耐受性。主成分分析和冗余分析表明,高浓度氨氮会促使产甲烷途径由乙酸利用型为主向氢利用型为主转变。     

磷酸盐对高基质厌氧氨氧化反应器脱氮性能的影响

采用模拟废水,在UASB反应器中研究磷酸盐对厌氧氨氧化(Anammox)工艺的长期影响,考察了厌氧氨氧化反应器处理高磷酸盐、高浓度含氮废水的可行性。结果表明:当磷酸盐在进水中的浓度低于750 mg·L~(-1)(25.8 mmol·L~(-1))时,Anammox工艺的脱氮效果较好,且磷酸盐浓度对废水中氮的去除及转化效果影响不大,当磷酸盐浓度增至800 mg·L~(-1)(25.8 mmol·L~(-1))时,Anammox工艺的脱氮性能被抑制,NH+4-N的去除率从96.5%降至74.1%,NO-2-N从97.8%降至75.6%,NRR(nitrogen removal rate)从5.7 kg·(m3·d)-1降至4.4 kg·(m3·d)-1。停止投加磷酸盐后,反应器的脱氮性能得到快速恢复。     

Fe3+对生物膜反应器去除模拟屠宰废水高氨氮的影响

为解决屠宰废水的高氨氮问题,在2 L SBBR中添加Fe~(3+)对模拟屠宰废水进行脱氮处理。在室温条件下,研究了不同浓度Fe~(3+)对NH_4~+-N、N O_2~--N、NO_3~--N、COD、同步硝化反硝化速率(ESND)、微生物群落分布的影响。结果表明,曝气量为0.6 L·min~(-1),HRT为12 h,Fe~(3+)质量浓度为10 mg·L~(-1)时,NH_4~+-N、COD和TN去除率分别为94%、97%和89.28%。N O_3~--N含量小于5 mg·L~(-1),NO2~--N含量接近0 mg·L~(-1),ESND平均值可达93.91%,比对照组高5.24%。Fe~(3+)提高了微生物抗低温冲击性,加快了同步硝化反硝化速率。高浓度的Fe~(3+)(30～50 mg·L~(-1))会产生生物毒性,抑制生物脱氮。SEM及显微镜观察发现,含有10 mg·L~(-1) Fe~(3+)的体系减少了生物质流失,微生物种类丰富,体系脱氮性能得到有效提升。     

猪粪与酒糟混合厌氧发酵的产甲烷和三元pH缓冲体系特征

以猪粪和酒糟为发酵原料,考察了5种混合比例（猪粪与酒糟总固体含量（TS）比100:0、95:5、90:10、80:20、50:50）下混合厌氧发酵的产甲烷特性,并研究了其三元pH缓冲体系特征。结果表明,混合比例显著影响猪粪与酒糟混合发酵的甲烷产率（P-1（VSadded））,比纯猪粪厌氧发酵的甲烷产率提高了6.2%。纯猪粪、猪粪与酒糟TS比为95:5的2组累积产甲烷量符合修正Gompertz方程(R2=0.993 3; R2=0.989 6),无明显滞后期。酒糟含有的大量硫酸盐影响了甲烷产量。VFAs-氨氮-TIC三元pH缓冲体系特征的研究结果表明,由于酒糟的碱度严重缺失,酒糟添加量过大时,体系偏离合适的pH缓冲区域,体系酸度过高,抑制了厌氧发酵的进行。     

UASB-PACT工艺处理有机颜料废水中试研究

针对颜料废水有机物浓度含量高、水质波动大、可生化性差等特点,实验采用了UASB-PACT(powdered activated carbon treatment)组合工艺在常温下对颜料废水进行中试研究。实验共进行了119 d,分2个阶段进行,第1阶段为低浓度运行阶段,进水COD逐步提升至3 000 mg·L~(-1)左右,经过36 d的运行,系统出水COD可稳定保持在500 mg·L~(-1)以下,UASB、PACT反应器对COD的平均去除率分别为37.0%和80.5%;第2阶段为负荷提高阶段,共运行了83 d,UASB、PACT反应器对COD的平均去除率分别为53.9%和81.7%。76 d后在平均进水浓度为6 207.75 mg·L~(-1)的条件下,出水COD500 mg·L~(-1)。在工程应用阶段,经过6个月的调试,在进水量1 920 m3·d-1、COD为5 000 mg·L~(-1)的条件下,UASB反应器的出水COD1 500 mg·L~(-1),PACT出水COD在300~500 mg·L~(-1)之间波动,去除率分别为50.9%和75.3%。实验结果表明,针对有机颜料废水,采用UASB-PACT组合工艺能够达到很好的处理效果,出水满足《污水排入城镇下水道水质标准》(CJ 343-2010)中A级排放要求。     

生活垃圾渗滤液对厌氧颗粒污泥产甲烷活性的影响研究

通过厌氧毒性实验、恢复实验和特征毒性模拟实验,研究了生活垃圾渗滤液对厌氧颗粒污泥微生物产甲烷活性的影响。结果表明,1 000 mg/L氨氮浓度下产甲烷活性均大于85%,说明相应氨氮浓度范围,垃圾渗滤液基质对厌氧颗粒污泥的微生物没有明显抑制作用。恢复实验后活性得到完全恢复,属代谢毒性。模拟废水氨氮浓度大于1 000 mg/L浓度时,开始出现抑制;氨氮浓度大于3 000 mg/L时,有明显抑制,产甲烷活性下降32.1%;相同氨氮浓度下,渗滤液最大活性区间滞后于模拟废水,产甲烷活性也小于模拟废水,存在除氨氮以外的毒性物质的影响。     

氨氮和腐殖酸对膜电容去离子技术去除垃圾渗滤液中无机离子的影响

高浓度氨氮及大量腐殖质的存在一直以来都是膜电容去离子技术(membrane capacitive deionization,MCDI)应用于垃圾渗滤液除盐的重要难题。采用PE离子交换膜作为膜材料,以活性交联碳布(activated carbon cloth,ACC)作为吸附材料组装MCDI装置,并对含有不同浓度梯度的氨氮和腐殖酸的模拟垃圾渗滤液进行吸附除盐实验。结果表明,垃圾渗滤液中氨氮浓度的增加会使MCDI对氨氮的去除量上升,但会导致Na~+、K~+和NO_3~-受到的影响较小。较低浓度腐殖酸(0～1 500 mg·L~(-1))的存在能一定程度促进MCDI对K~+和NH_4~-的吸附,但过高的腐殖酸(1 500～2 000 mg·L~(-1))浓度会导致所有无机离子特别是阴离子吸附量的下降,且腐殖酸的存在也会降低MCDI对所有离子的再吸附效果,减小MCDI的使用寿命。对垃圾渗滤液进行预处理,将氨氮和腐殖酸的浓度降低,有利于提高MCDI的去离子效果。     

人工湿地型微生物燃料电池处理啤酒生产废水

采用人工湿地型微生物燃料电池处理啤酒生产废水,考察了啤酒生产废水中不同COD浓度条件下(475、1 968、5 640 mg·L~(-1))人工湿地型微生物燃料电池对COD和氨氮的去除效果,评估了在此过程中微生物燃料电池的产电性能。研究表明,当COD浓度为1 968 mg·L~(-1)时,人工湿地型微生物燃料电池对COD的去除率最高,达到93.5%;氨氮去除率随COD起始的增加而增加,当进水浓度为5 640 mg·L~(-1)时,氨氮去除率达到70.8%。对产电性能而言,当进水COD浓度为1 968 mg·L~(-1)时,人工湿地型微生物燃料电池产电量最高,其最大电压、功率密度和电流密度分别达到280 mV、24.2 mW·m~(-2)和220 mA·m~(-2)。利用人工湿地型微生物燃料电池处理啤酒生产废水具有一定的可行性,在处理污染物的同时产电,弥补了处理过程中的能源消耗,对废物资源化具有很好的应用前景。     

工程规模下碱类型对污泥预处理效果及发酵产酸的影响

研究了工程规模下3种碱对剩余污泥热碱预处理效果以及厌氧发酵产酸的影响。结果表明,平均进泥浓度为70 g·L~(-1)时,氢氧化钠的预处理效果要优于混碱(Ca(OH)_2:NaOH=4:1)和过氧化钙,处理后污泥中溶解性化学需氧量(SCOD)的平均浓度是预处理前的8.45倍,水解率达到64.26%。但是,使用过氧化钙进行预处理可以有效提高污泥的发酵产酸效果,产酸效率明显优于混碱和氢氧化钠,总挥发性脂肪酸(TVFAs)的平均浓度为7.93 g·L~(-1),产酸率(以COD计)为273.93 mg·g~(-1)VSS,且总酸中乙酸比例达到60.35%;发酵后平均TSS和VSS分别下降了24.42%和47.62%;同时,氨氮(NH_4~+-N)和总磷(TP)浓度最低,其平均浓度分别为286.33 mg·L~(-1)和17.42 mg·L~(-1)。此外,混碱组、过氧化钙组和氢氧化钠组污泥厌氧发酵的净利润分别为229.14、257.37和10.49元·t~(-1)(脱水污泥)。实验结果表明,热混碱和热过氧化钙预处理用于污泥厌氧发酵有望得到广泛的应用。     

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.