高架道路降雨径流水质的污染控制试验研究

通过模拟上海高架道路降雨径流水质,基于生物滞留设施的原理设计小试和中试反应器,对比了以陶粒和沸石为介质的生物滞留设施对高架道路雨水径流的处理条件及效果,初步讨论了介质层结构对处理效果的影响。结果表明,基质强化生物滞留设施的水力负荷应不大于1m~3/(m~2·d);沸石基质对COD、TP和NH_3-N的去除效果好于陶粒,其相应去除率分别为74%、87%和71%,装置运行期间出水水质达到《地表水环境质量标准》(GB 3838—2002)中Ⅲ类标准;沸石基质适应水力负荷范围较大,更适于处理水力负荷变化较大的雨水径流;添加沸石层后单位时间内污染物去除效率提高40%左右。     

携菌新型生物质基材用于微污染水体治理

针对河道微污染水,以农林秸秆生物质发电后的废料制成的生物质基材为填料,将异养硝化菌Pseudomonas固定于其中,采用人工湿地模拟装置考察携菌生物质基材对微污染河道水体的处理效果,并与火山岩进行比较;借助高通量测序技术对生物膜的微生物群落进行解析,最后将携菌生物质基材应用于河道净化工程中。结果表明:携菌生物质基材对进水COD、NH~+_4-N、TP的去除率分别达到81.0%、98.2%、96.7%,其除污效果及稳定性均优于火山岩。生物质基材的微生物群落结构以Alphaproteobacteria菌属(36%)和Pseudomonas菌属(13%)为主,表明生物质基材携带增效菌种Pseudomonas后在脱氮方面有较大优势。将携菌生物质基材应用于处理量为150m~3/d的城市内河点源污染治理工程,携菌生物质基材可进一步稳定去除传统AO装置尾水中的COD、NH~+_4-N和TP,出水水质可达到地表Ⅳ类水标准,且生物质基材所携带Pseudomonas仍占据一定比例(0.65%)。     

变频水泵装置调速特性试验研究

介绍了试验条件及数据处理方法,对变频水泵装置的扬程、流量、总功率、总效率随频率的变化规律通过试验进行了分析。结果表明:转速比的平方不等于扬程比,转速比的立方不等于功率比;相对频率比为84%~100%时,流量比等于转速比;相对频率比大于0.5,小于1时,降低频率,节能效果显著;相对频率比小于0.28时,继续降低频率,变频水泵装置节能潜力不大。     

密闭式顶盖对渣土车遗撒和风蚀扬尘的控制效果

目的渣土车遗撒和风蚀扬尘是道路扬尘污染的突出问题,为推广密闭式顶盖提供技术依据,对渣土车遗撒量和风蚀扬尘率进行测试。方法利用自制遗撒测试装置测试有无密闭式顶盖的渣土车行驶过程遗撒量,在未密闭货车车厢内均匀撒定量水泥,测试货车行驶过程水泥风蚀量。结果密闭式顶盖安装前后的渣土车超载运输建筑渣土,遗撒量分别为4.0 kg/车和0.2 kg/车,控制效率为95%。北京市2011年渣土车全部安装密闭式顶盖后,渣土遗撒量可由2.67万t/年削减为0.13万t/年。未密闭渣土车运输袋装水泥空车返回时,车速50 km/h时风蚀扬尘率约为35%。结论渣土车应安装机械式全密闭装置,顶盖距离车厢上沿高度应小于等于5 cm,在用渣土车满载干燥渣土在行驶过程中,渣土遗撒量应小于等于0.25 kg/车。     

初期雨水径流污染路面拦截装置

为了有效控制路面初期雨水径流污染,基于海绵城市设计思想,开发了一种新型的雨水路面拦截装置,分析其收集、净化、下渗排放作用原理,对拦截装置的截流净化效率进行实测,结果显示:装置对污染物质具有较好的拦截、净化效率,能够有效拦截初期径流污染物,控制径流污染.     

生物强化接触氧化工艺原位修复受氮素污染水体

某受氮素污染河水采用接触氧化工艺处理但效果不理想,为此,模拟该河水真实流态而构建了小试装置,通过功能菌群调查,富集、驯化培养土著氨氧化菌(AOB)和亚硝酸盐氧化菌(NOB)并持续投加至好氧段,以强化硝化菌群、提高脱氮效果。采取生物强化措施后,系统对总氮和氨氮的去除率分别提高了约26%和20%;出水中的AOB和NOB菌群数量分别增加了近103和104倍,好氧段生物膜中的AOB和NOB菌群数量均增加了近102倍。DGGE图谱分析也表明,投加高效菌剂后,系统中的微生物群落结构发生了明显变化,新增的优势微生物种群与Nitrosomonassp.和Nitrobacter sp.具有高度同源性,说明系统内去除氮素的关键微生物种群得到了增强。     

次氯酸钠控制城市污水处理厂微丝菌污泥膨胀

针对由微丝菌引起的城市污水处理厂营养物去除系统的活性污泥膨胀,采用投加次氯酸钠进行氧化控制,探讨不同剂量下次氯酸钠对微丝菌的杀灭效果、活性污泥沉降性能的改善以及对功能微生物(聚磷菌)的损伤和恢复。结果表明,次氯酸钠使裸露于絮体外的菌丝断裂,污泥容积指数减小;随着非丝状菌的增殖和剩余污泥排出,活性污泥沉降性能进一步改善;次氯酸钠的投加量越高,对聚磷菌吸磷和释磷速率影响越大,但聚磷菌释磷速率减小的幅度小于吸磷速率。最佳投药量为5.3 g Cl/kg MLSS,此时SVI由未投加次氯酸钠时的202 m L/g降至134 m L/g,最大释磷速率和最大吸磷速率同比分别降低了11%和40%。可见,投加次氯酸钠能有效控制微丝菌引起的污泥膨胀。     

固定化微生物修复石油污染土壤特性试验

利用梯度稀释法分离筛选原油降解混合菌,采用吸附法将混合菌固定在砾石和草炭土上,探讨固定化混合菌对土壤石油烃的去除效果。结果表明:分离得到的混合菌8-2,菌群结构简单,石油烃降解率可达52.1%。与砾石相比,草炭土所固定的微生物数量和活性较高,可达1.3×108 cfu/g和0.24A487。草炭土固定的混合菌8-2,修复含油量为30g/kg的污染土壤30d后,石油烃降解率达28.4%,高于游离降解菌的24.3%。固定化载体草炭土在修复过程中起到了微生物缓释剂的作用。     

通乡公路水泥稳定碎石基层施工的质量控制

1原材料质量控制1.1水泥水泥稳定碎石基层可使用硅酸盐水泥、矿渣硅酸盐水泥、火山灰硅酸盐水泥,禁止使用快硬水泥、早强水泥。我县通乡公路大多使用本县龙海、朴塘水泥厂生产的P032.5普通硅酸盐水泥。该水泥各龄期强度、安定性等均达到相应指标要求,同时水泥初凝时间不小于3 h、终凝时间不小于6 h。1.2碎石我县碎石储量较为丰富,石料强度较高,水泥稳定碎石混合料中,碎石压碎值不大于30%,针片状含量不大于15%,集料中小于0.6 mm的颗粒必须做液限和塑性指数试验,确定水泥稳定碎石基层采用的颗粒组成范围。见表1。压碎值不大于30%,液限不超过25%,塑性指数小于6,有机质含量不超过2%,硫酸盐含量不超过0.25%等。表1颗粒组成范围筛孔尺子37.5 31.5 19 9.5 4.75 2.36 0.6 0.075通过质量百分率%100 90~100 67~90 45~68 29~50 18~38 8~22 0~7 1.3河砂我县河砂产量大,分布均匀,质量完全符合规范要求,施工中应采用质地坚硬、耐久、洁净细度模数在3.0~2.3之间的天然河砂,其技术指标应符合规范要求,河砂的级配要求也应符合规范规定,河砂中有害杂质含量...     

通风与空气过滤对控制室内生物污染的影响研究

在分析室内空气微生物的来源、存活及传播等规律的基础上,介绍了通风与空气过滤两种建筑室内生物污染工程控制方法,采用微积分方法建立了通风过滤模型,分析了通风对降低室内生物污染浓度的影响,给出了通风空调系统各空气过滤器滤菌效率的设计计算公式。理论计算结果表明当以控制室内生物污染为主要目的时,自然通风效果不佳,应考虑机械通风;提高集中空调系统的各级过滤器滤菌效率,有助于改善室内生物污染状况。     

舒适性空调系统的临界净化效率与最小换气次数

指出舒适性空调应同时满足健康和舒适要求，从室内空气中有害物质量平衡方程导出舒适性空调系统临界净化效率和最小换气次数，认为依靠增加新风量来改善室内空气品质的作用是有限的，在满足室内要求的基本新风量后，提高各级空气净化器效率才有助于改善空气品质，据作者的观点设计空调系统其方法将有别于传统设计。     

Performance of ultraviolet photocatalytic oxidation for indoor air cleaning applications

Ultraviolet photocatalytic oxidation (UVPCO) systems for removal of volatile organic compounds (VOCs) from air are being considered for use in office buildings. Here, we report an experimental evaluation of a UVPCO device with tungsten oxide modified titanium dioxide (TiO2) as the photocatalyst. The device was challenged with complex VOC mixtures. One mixture contained 27 VOCs characteristic of office buildings and another comprised 10 VOCs emitted by cleaning products, in both cases at realistic concentrations (low ppb range). VOC conversion efficiencies varied widely, usually exceeded 20%, and were as high as approximately 80% at about 0.03 s residence time. Conversion efficiency generally diminished with increased airflow rate, and followed the order: alcohols and glycol ethers > aldehydes, ketones, and terpene hydrocarbons > aromatic and alkane hydrocarbons > halogenated aliphatic hydrocarbons. Conversion efficiencies correlated with the Henry's law constant more closely than with other physicochemical parameters. An empirical model based on the Henry's law constant and the gas-phase reaction rate with hydroxyl radical provided reasonable estimates of pseudo-first order photocatalytic reaction rates. Formaldehyde, acetaldehyde, acetone, formic acid and acetic acid were produced by the device due to incomplete mineralization of common VOCs. Formaldehyde outlet/inlet concentration ratios were in the range 1.9-7.2. PRACTICAL IMPLICATIONS: Implementation of air cleaning technologies for both VOCs and particles in office buildings may improve indoor air quality, or enable indoor air quality levels to be maintained with reduced outdoor air supply and concomitant energy savings. One promising air cleaning technology is ultraviolet photocatalytic oxidation (UVPCO) air cleaning. For the prototype device evaluated here with realistic mixtures of VOCs, conversion efficiencies typically exceeded the minimum required to counteract predicted VOC concentration increases from a 50% reduction in ventilation. However, the device resulted in the net generation of formaldehyde and acetaldehyde from the partial oxidation of ubiquitous VOCs. Further development of the technology is needed to eliminate these hazardous air pollutants before such a UVPCO device can be deployed in buildings.     

治理污染也是为了节能——空调净化系统污染控制与节能关系系列研讨之二

空调系统的污染治理是节能的重要措施,污染治理可以防止风管积尘、节省清洗费用、降低换热器阻力、避免换热器换热能力降低等。空调系统的污染治理不是指事后清洗,而是用阻隔式过滤器把90%以上的灰尘阻挡在新、回风口之外。     

室内空气净化技术的研究与进展

介绍了净化室内不同空气污染物采取的相应净化技术,针对室内VOC,常用吸附法、光催化法、纳米材料净化法;针对室内空气颗粒物,主要采用机械过滤、静电除尘技术、低温等离子体技术、纳米光催化技术等,而微生物的净化主要是利用纳米TiO2光催化技术。还介绍了生物净化技术、膜分离技术等室内空气净化技术的最新进展。     

Flow impact of an air conditioner to portable air cleaning

In order to reduce indoor pollutant exposure, people become increasingly interested in portable air cleaning devices, which can be positioned with flexibility. Such purification devices usually discharge cleaned air with strong momentum, which can interrupt indoor airflow created by air-conditioning units. If a well-organized air circulation to a portable air cleaner is not achieved, indoor air purification cannot be fully ensured. This study has used both measurement and computational fluid dynamics (CFD) modeling to investigate the flow interaction between an air conditioner and a portable air cleaner to purify indoor gaseous pollutants. A workshop environment conditioned by an air conditioner and cleaned by a portable air cleaner was mimicked in an environmental chamber to obtain data for validation of a CFD program. Then CFD was applied to evaluate factors that may affect air purification including: positioning of the air conditioner and air cleaner, air conditioner diffuser types, air-conditioning cooling or heating running mode, and location of pollutant sources. The study finds the simulation results are in good agreement with the corresponding experimental data. The positioning coordination of an air conditioner and an air cleaner, and selection of air conditioner diffuser types shall assure a good air circulation cycle to the air cleaner to improve air purification efficacy. In addition to the cleaner effectiveness, it is also recommended to evaluate an air cleaning device in terms of the absolute pollutant concentration, if the portable air cleaner is under the interaction of an air conditioner and the local performance data are interested.     

Significant OH production under surface cleaning and air cleaning conditions: Impact on indoor air quality

We report measurements of hydroxyl (OH) and hydroperoxy (HO₂) radicals made by laser‐induced fluorescence spectroscopy in a computer classroom (i) in the absence of indoor activities (ii) during desk cleaning with a limonene‐containing cleaner (iii) during operation of a commercially available “air cleaning” device. In the unmanipulated environment, the one‐minute averaged OH concentration remained close to or below the limit of detection (6.5×10⁵ molecule cm^?3), whilst that of HO₂ was 1.3×10⁷ molecule cm^?3. These concentrations increased to ~4×10⁶ and 4×10⁸ molecule cm^?3, respectively during desk cleaning. During operation of the air cleaning device, OH and HO₂ concentrations reached ~2×10⁷ and ~6×10⁸ molecule cm^?3 respectively. The potential of these OH concentrations to initiate chemical processing is explored using a detailed chemical model for indoor air (the INDCM). The model can reproduce the measured OH and HO₂ concentrations to within 50% and often within a few % and demonstrates that the resulting secondary chemistry varies with the cleaning activity. Whilst terpene reaction products dominate the product composition following surface cleaning, those from aromatics and other VOCs are much more important during the use of the air cleaning device.     

Achieving 'excellent' indoor air quality in commercial offices equipped with air-handling unit--respirable suspended particulate

A study was carried out to investigate the feasibility of achieving ultra low respirable suspended particulates (RSP) in commercial offices without major modification of existing ventilation systems by enhancing the particulates removal efficiency of existing central ventilation systems. Four types of filters which include pre-filters, cartridge filters, bag filters and high efficiency particulates air (HEPA) filters were tested in a commercial building in Causeway Bay. The results show that an RSP objective of <20 microg/m3 could be met by removing RSP from both the return air and outdoor air supply simultaneously. This level of performance is classed as 'excellent' by the Hong Kong Government, Environmental Protection Department. Filters with efficiency that exceed 80% placed both in the return air and outdoor air were sufficient to meet the objective. It is not necessary to install HEPA filters to achieve the 'excellent' class. The outdoor air filter has great influence on the steady state indoor RSP concentration while the effective cleaning rate is governed by the return air filter. Higher efficiency filters increased the static drop but the volume flow of the air fan was not affected significantly. The additional cost incurred was <5% of the existing operation cost. PRACTICAL IMPLICATIONS: This paper reports a field study of RSP control for an indoor office environment. The results are directly applicable to building service engineering in the design of ventilation systems using air-handling units. Field observations indicated that indoor RSP in an office environment could be suppressed below 20 microg/m3 within 1 h by the simultaneous filtration of outdoor air and return air. Outdoor air filtration has a great influence on the steady state indoor concentration and return air filtration governs the cleaning rate. It is believed that the results of this study could be extended to the cleaning of other indoor pollutants such as volatile organic compounds.     

Penetration of nitrogen oxides and particles from outdoor into indoor air and removal of the pollutants through filtration of incoming air

We studied the effect of ventilation and air filtration systems on indoor air quality in a children's day-care center in Finland. Ambient air nitrogen oxides (NO, NO2) and particles (TSP, PM10) were simultaneously measured outdoors and indoors with automatic nitrogen oxide analyzers and dust monitoring. Without filtration nitrogen oxides and particulate matter generated by nearby motor traffic penetrated readily indoors. With chemical filtration 50-70% of nitrogen oxides could be removed. Mechanical ventilation and filtration also reduced indoor particle levels. During holidays and weekends when there was no opening of doors and windows and no particle-generating activity indoors, the indoor particle level was reduced to less than 10% of the outdoor level. At times when outdoor particle concentrations were high during weekdays, the indoor level was about 25% of the outdoor level. Thus, the possible adverse health effects of nitrogen oxides and particles indoors could be countered by efficient filtration. We also showed that inclusion of heat recovery equipment can make new ventilation installations economical.     

Photolysis-driven indoor air chemistry following cleaning of hospital wards

Effective cleaning techniques are essential for the sterilization of rooms in hospitals and industry. No-touch devices (NTDs) that use fumigants such as hydrogen peroxide (H₂O₂), formaldehyde (HCHO), ozone (O₃), and chlorine dioxide (OClO) are a recent innovation. This paper reports a previously unconsidered potential consequence of such cleaning technologies: the photochemical formation of high concentrations of hydroxyl radicals (OH), hydroperoxy radicals (HO₂), organic peroxy radicals (RO₂), and chlorine radicals (Cl) which can form harmful reaction products when exposed to chemicals commonly found in indoor air. This risk was evaluated by calculating radical production rates and concentrations based on measured indoor photon fluxes and typical fumigant concentrations during and after cleaning events. Sunlight and fluorescent tubes without covers initiated photolysis of all fumigants, and plastic-covered fluorescent tubes initiated photolysis of only some fumigants. Radical formation was often dominated by photolysis of fumigants during and after decontamination processes. Radical concentrations were predicted to be orders of magnitude greater than background levels during and immediately following cleaning events with each fumigant under one or more illumination condition. Maximum predicted radical concentrations (1.3 × 10⁷ molecule cm⁻³ OH, 2.4 ppb HO₂, 6.8 ppb RO₂ and 2.2 × 10⁸ molecule cm⁻³ Cl) were much higher than baseline concentrations. Maximum OH concentrations occurred with O₃ photolysis, HO₂ with HCHO photolysis, and RO₂ and Cl with OClO photolysis. Elevated concentrations may persist for hours after NTD use, depending on the air change rate and air composition. Products from reactions involving radicals could significantly decrease air quality when disinfectants are used, leading to adverse health effects for occupants.     

加强空调风管清洗维护的必要性

阐述了空调风管清洗维护的必要性，介绍了风管尘埃污染物的分布情况与危害性，论述了风管清扫的方法与技巧，以提高空调效率，节约能源，提高人民的生活水平。