共查询到20条相似文献，搜索用时 15 毫秒
1.
Due to the importance of biological safety in drinking water quality and the disadvantages which exist in traditional methods of detecting typical microorganisms such as Cryptosporidium and Giardia, it is necessary to develop an alternative. Particle counts is a qualitative measurement of the amount of dissolved solids in water. The removal rate of particle counts was previously used as an indicator of the effectiveness of a biological activated carbon （BAC） filter in removing Cryptosporidium and Giardia. The particle counts in a BAC filter effluent over one operational period and the effects of BAC filter construction and operational parameters were investigated with a 10 m^3/h pilot plant. The results indicated that the maximum particle count in backwash remnant water was as high as 1296 count/ml and it needed about 1.5 h to reduce from the maximum to less than 50 count/ml. During the standard filtration period, particle counts stay constant at less than 50 count/ml for 5 d except when influenced by sand filter backwash remnant water. The removal rates of particle counts in the BAC filter are related to characteristics of the carbon. For example, a columned carbon and a sand bed removed 33.3% and 8.5% of particles, respectively, while the particle counts in effluent from a cracked BAC filter was higher than that of the influent. There is no significant difference among particle removal rates with different filtration rates. High post-ozone dosage （〉2 mg/L） plays an important role in particle count removal; when the dosage was 3 mg/L, the removal rates by carbon layers and sand beds decreased by 17.5% and increased by 9.5%, respectively, compared with a 2 mg/L dosage. 相似文献
2.
Decomposition of dimethyl sulfide （DMS） in air was investigated experimentally by using a wire-cylinder dielectric barrier discharge （DBD） reactor at room temperature and atmospheric pressure. A new type of high pulse voltage source with a thyratron switch and a Blumlein pulse-forming network （BPFN） was adopted in our experiments. The maximum power output of the pulse voltage source and the maximum peak voltage were 1 kW and 100 kV, respectively. The important parameters affecting odor decomposition, including peak voltage, pulse frequency, gas flow rate, initial concentration, and humidity, which influenced the removal efficiency, were investigated. The results showed that DMS could be treated effectively and almost a 100% removal efficiency was achieved at the conditions with an initial concentration of 832 mg/m3 and a gas flow rate of 1000 ml/min. Humidity boosts the removal efficiency and improves the energy yield （EY） greatly. The EY of 832 mg/m3 DMS was 2.87 mg/kJ when the relative humidity was above 30%. In the case of DMS removal, the ozone and nitrogen oxides were observed in the exhaust gas. The carbon and sulfur elements of DMS were mainly converted to carbon dioxide, carbon monoxide and sulfur dioxide. Moreover, sulfur was discovered in the reactor. According to the results, the optimization design for the reactor and the matching of high pulse voltage source can be reckoned. 相似文献
3.
ZHANG Hong-jing LONG Teng-rui CAO Yan-xiao 《重庆大学学报(英文版)》2006,5(3):152-156
1 Introduction ? The biological aerated filter technique has developed rapidly since 1980s, and is widely used in municipal sewage treatment. It has been used in the primary and secondary treatment processes due to its desirable economical efficiency and … 相似文献
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5.
球形果蔬差压预冷过程实验研究 总被引：1，自引：0，他引：1
通过搭建的果蔬差压预冷实验台分别研究了不同的送风速度、开孔大小、开孔形状及排列方式,对球形果蔬在差压预冷过程中所产生的影响,实验结果发现：风速越大球形果蔬降温速率越快,冷风送风速度1.5～2m/s为最经济送风风速;椭圆形的送风口球形果蔬降温速度最快;交叉排列摆放方式降温速度快,但降温的均匀性较差; 相似文献
6.
武夷山市人工湿地系统采用水解酸化+接触氧化+垂直流人工湿地处理工艺处理城市生活污水,经过5年多的运行,结果表明系统对COD的净化效果好。近17个月的监测数据显示,COD的去除率超过92%,系统出水水质达到《城镇污水处理厂污染物排放标准》的一级A标准。此外,人工湿地系统处理城市生活污水的耗能低(平均的耗电量为0.14 kWh/m3),节省日常的运行费用。 相似文献
7.
为研究离心式分离腔体内部气流流动轨迹以及梗丝颗粒的运动规律,进一步深入研究梗丝分离效果,基于ANSYS建立流体域模型,利用流体仿真软件Fluent,采用RNG湍流模型模拟腔体内气流轨迹,拉格朗日离散相模型（DPM）模拟颗粒相运动规律,得到腔体内气流轨迹、压力和颗粒相运动轨迹云图,并在入口处设定不同大小的气流速度,当入射速度为6m/s时,气流流动轨迹发生改变,达到8m/s时气流轨迹比较理想,且颗粒运动轨迹正确。此时梗丝在离心分离腔体内可以得到有效分离,梗中含丝率降低到2.55%左右,烟丝利用率进一步提高。 相似文献
8.
INTRODUCTION With the development of industry, more and more pollutants are discharged into environment, among them, phenolic wastes are typical contami-nants considered to be hazardous and top priority toxic pollutants listed by the USEPA. They are toxic even at low concentration. Due to their biorefractory, bioaccumulation and carcinogenic potential, the treatment of these contaminants is very important in environmental protection. Various technologies and processes have been tried … 相似文献
9.
A novel in-situ electrochemical oxidation method was applied to the degradation of wastewater containing chlorophenol. Under oxygen sparging, the strong oxidant, hydrogen dioxide, could be in-situ generated through the reduction of oxygen on the surface of the cathode. The removal rate ofchlorophenol could be increased 149% when oxygen was induced in the electrochemical cell. The promotion factor was estimated to be about 82.63% according to the pseudo-first-order reaction rate constant (min-1). Important operating parameters such as current density, sparged oxygen rate were investigated.Higher sparged oxygen rate could improve the degradation of chlorophenol. To make full use of oxygen, however, sparged oxygen rate of 0.05 m3/h was adopted in this work. Oxidation-reduction potential could remarkably affect the generation of hydrogen peroxide. It was found that the removal rate of chlorophenol was not in direct proportion to the applied current density. The optimum current density was 3.5 mA/cm2 when initial chlorophenol concentration was 100 mg/L and sparged oxygen rate was 0.05 m3/h. 相似文献
10.
Removal of chromium (VI) dissolved in water by intermittent foam separation was implemented with cetyl trimethy-ammonium bromide
as surfactant. The influence of various factors on removal efficiency was systematically studied. The removal efficiency has
a maximum value near pH 4.0; thus, most experiments were carried out at pH 4.0. The orthogonal experiment was conducted to
confirm the optimal operating parameters. The orthogonal experimental results show that when the liquid feed concentration
is 10 mg/L, the pH value of feed solution is 4.00, air flow rates 0.9 L/min, surfactant dosage is 300 mg/L, the maximum removal
efficiency of chromium (VI) reaches 97.80%, and condense multiple reaches 1 711. The kinetic test indicates that the foam
separation of chromium is a first-order process. The equivalent rate constant calculated from the slope is 0.406 4, and the
equivalent rate equation is obtained. 相似文献
11.
雷玉勇 《重庆大学学报(英文版)》2003,2(1)
1. Introduction With the development of transportation, more and more road tunnels, especially the long tunnels, such as Erlangshan Tunnel (4176 m, China), Arlberg Tunnel (13972 m, Austria), Kan-etsu Tunnel (11055 m, South tube, Japan) and Laerdal Tunnel (24510m, Norway) have been built on the highway lines [1]. In a road tunnel, the exhaust gases given off by automobile engines, such as smoke, carbon monoxide (CO), oxynitride (NOx), hydrocarbon, etc., and dust produced by the passing a… 相似文献
12.
A laboratory-scale trickling biofilter column,filled with Raschig rings and inoculated with Pseudomonas putida (ATCC 1785)was used to purify chlorobenzene contained waste gases.Sodium dodecyl sulfonate(SDS)was used to enhance the performance of trickling biofllter.Purification performance of the trickling biofilter was examined for chlorobenzene inlet concentration of 1.20～5.04 g/m~3 at different EBRTs between 76～153 s.Without SDS addition,with simultaneous increase in chlorobenzene inlet loading rate and gas flow rate,100% removal efficiency was achieved at EBRT of 109 s and inlet loadings below 5120 mg/m~3.Addition of SDS to nutrient solution led to improvement of trickling biofilter purification performance. By introducing 25 mg/L SDS,the removal efficiency was increased by 21% and elimination capacity up to 234 g/(m~3.h)was achieved at chlorobenzene inlet loading of 241 g/(m~3.h).Although SDS concentration experienced a low rate reduction after continuous nutrient solution recirculation,this result has little influence on trickling biofilter's removal efficiency in monitoring period. 相似文献
13.
Indoor environment separated with down.feed air curtain was numerically simulated and experimentally researched.Indoor airflow and temperature fields separated with air curtain were numerically simulated.Resuits show that both polluted airflow and thermal air current can be separated with a down.feed air curtain to prevent contaminants from spreading in the room space.In a test chamber.the smoke of burning Tibetan incense served as the source of contaminants.and the probe test shows that 1.0 pm is the prevailing diameter of the smoke particles.During the release of the smoke.the particle concentration of the indoor air was tested with a laser particle counter at the points of three different heights from the floor when the air curtain was running or not.Experimental results show that the higher the test point is located,the lower the particle concentration is,implying that the separating or isolating eflfect decreases as the air velocity of the curtain reduces along with the height descends.According to both simulation and experimental results.down.feed air curtain can separate indoor environment effectively when the supply air velocity of air curtain is not less than 3 m/s.In order to strengthen separation effect,it is suggested that the supply air velocity be speeded up to 5 m/s. 相似文献
14.
Computational fluid dynamics simulation of formaldehyde emission characteristics and its experimental validation in environment chamber 总被引：1，自引：0，他引：1
We investigated the effect of supply air rate and temperature on formaldehyde emission characteristics in an environment chamber. A three-dimensional computational fluid dynamics （CFD） chamber model for simulating formaldehyde emission in twelve different cases was developed for obtaining formaldehyde concentration by the area-weighted average method. Laboratory experiments were conducted in an environment chamber to validate the simulation results of twelve different cases and the formaldehyde concentration was measured by continuous sampling. The results show that there was good agreement between the model prediction and the experimental values within 4.3% difference for each case. The CFD simulation results varied in the range from 0.21 mg/m3 to 0.94 mg/m3, and the measuring results in the range from 0.17 mg/m3 to 0.87 mg/m3. The variation trend of formaldehyde concentration with supply air rate and temperature variation for CFD simulation and experiment measuring was consistent. With the existence of steady formaldehyde emission sources, formaldehyde concentration generally increased with the increase of temperature, and it decreased with the increase of air supply rate. We also provided some reasonable suggestions to reduce formaldehyde concentration and to improve indoor air quality for newly decorated rooms. 相似文献
15.
Xiao-hong Mao Jian-you Wang Jian-liang Yan 《Journal of Zhejiang University. Science. B》2012,13(9):745-750
Objective:To evaluate the clinical effect of topical imiquimod treatment on cutaneous vascular disorders in pediatric patients.Methods:A retrospective investigation was conducted in 25 pediatric patients with cutaneous vascular disorders,including 19 infantile hemangiomas(IHs)(12 superficial/7 mixed type),5 nevus flammeus(NF),and 1 pyogenic granuloma(PG).Imiquimod 5% cream was applied every other day for 4 to 16 weeks(average 9.6 weeks).Results:Of the 19 IHs treated,an overall efficacy of 52.6% was achieved,with a clinical resolution rate of 15.8%,excellent rate of 26.3%,and moderate rate of 10.5%.The superficial type responded the best at 66.7%,while the mixed type showed only 28.6% effectiveness,which was predominantly from their superficial parts.No obvious response was noted in the 5 patients with NF.Side effects were observed in 78.9% of the patients,mostly mild to moderate local irritations and occasionally severe reactions such as thick crusting and ulceration.Systemic side events were observed in 4 IH patients including fever and digestive tract reactions.No recurrence was observed during the follow-up examination.Conclusions:Topical imiquimod could be an alternative option for the treatment of uncomplicated superficial IHs with satisfactory tolerability. 相似文献
16.
In the current studies a miniature silicon wafer fuel cell （FC） using L-ascorbic acid as fuel was developed. The cell employs L-ascorbic acid and air as reactants and a thin polymer electrolyte as a separator. Inductively coupled plasma （ICP） silicon etching was employed to fabricate high aspect-ratio columns on the silicon substrate to increase the surface area. A thin platinum layer deposited directly on the silicon surface by the sputtering was used as the catalyst layer for L-ascorbic acid electro-oxidation. Cyclic voltammetry shows that the oxidation of L-ascorbic acid on the sputtered platinum layer is irreversible and that the onset potentials for the oxidation of L-ascorbic acid are from 0.27 V to 0.35 V versus an Ag/AgCl reference electrode. It is found that at the room temperature, with 1 mol/L L-ascorbic acid/PBS （phosphate buffered solution） solution pumped to the anode at 1 ml/min flow rate and air spontaneously diffusing to the cathode as the oxidant, the maximum output power density of the cell was 1.95 mW/cm^2 at a current density of 10 mA/cm^2. 相似文献
17.
研究电化学方法制备高铁酸钾,通过单因素实验确定最佳工艺条件为:电解液KOH浓度16 mol/L,电解时间为6 h,反应温度为65 ℃,阳极表观电流密度为50 A/m2,制得高铁酸钾的浓度可达5.72 mmol/L。对高铁酸钾强化电动修复技术去除土壤中的苯酚进行初探,结果表明该技术可以大幅度提高苯酚污染的修复效能,在反应120 h后,苯酚的去除率可达到90%以上,而且产生的Fe(OH)3固体无毒无害,不会对环境造成二次污染。 相似文献
18.
The effects of particle size of activated carbon （AC） on its wettability, electrode coating technology and electric chemical performance were studied to assemble nonaqueous electric double layer capacitors （EDLCs） for high power requirements. The results show that the specific surface area and total pore volume of AC decrease from 2 137 m^2/g to 1 683 m^2/g, and 0.95 cm^3/g to 0.78 cm^3/g, respectively, if it is ball-milled for 8 h. The pore size distributions are similar in the range of 0.7 nm to 3.5 nm for different ball-milling time. There exists oxidation on the surface of AC during the ball-milling process and the ratios of O-C=O oxygen compositions increase whereas those of C-O, C=O decrease. The peeling strength of AC coated on current collector is almost inverse proportion with the particle size of AC as well as the resistance of EDLCs, and its capacitance decreases about 6%. 相似文献
19.
采用RAD-7型电子连续测氡仪,对某大学新校区室内氡浓度进行检测与研究．结果显示：室内空气中氡浓度与温度、相对湿度成正比;底层建筑室内氡浓度的峰值出现在14-17h时段,与土壤中氡浓度变化规律一致,说明室内空气中氡与房屋地基下的岩石、土壤类型及相关的建筑材料有关;3楼、6楼的氡浓度变化波峰出现在6～11h时段,波谷出现在14～17h时段;由检测数据可知,大部分室内氡浓度值低于200Bq／m3,部分超过200Bq／m3．建议常开门窗,加大通风量以稀释室内氡及其子体的浓度,将其排放到室外． 相似文献
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通过露天水稻盆栽试验,模拟自然环境研究MTBE在水、土壤和水稻中的迁移转化规律及其对水稻性状影响。结果表明,MTBE在水中的溶解量远大于其在土壤中的吸附量,MTBE在水中的消失速率快于土壤中的消失速率;同时研究了水稻体内MTBE分布规律;另外研究了MTBE对水稻叶片中的光合色素、游离脯氨酸和丙二醛的含量的影响及对水稻籽粒质量的影响。 相似文献