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641.
642.
城市污水处理厂第二沉淀池出水的污染物浓度较低,经过矿化及灭菌等深度处理后可以回用,从而减轻对淡水资源的需求。本实验采用溶胶-凝胶法制备了负载TiO2的浮石光催化剂,对城市污水处理厂第二沉淀池出水进行了矿化及灭菌处理研究。采用低压汞灯对处理水样照射2h,有机物降解率可以达到50%,灭菌效率达到100%。处理后的水可以作为农作物灌溉、城市绿化和娱乐用水。负载在浮石表面的TiO2薄膜经过10次的光催化循环实验后,没有明显破损,可以再次循环使用。TiO2浮石具有质轻、机械性能好和价格低等优点,该方法处理废水的适用浓度低,可以广泛应用于微污染水和城市污水处理厂出水的深度处理。 相似文献
643.
通过恒温振荡平衡法研究了Pb~(2+)在针铁矿上的等温吸附和吸附动力学特征,探讨了吸附的影响因素.结果表明:(1)随Pb~(2+)平衡浓度和pH的增大,针铁矿对Pb~(2+)的吸附量逐渐增大.(2)针铁矿对Pb~(2+)的等温吸附可用Freundlich和Langmuir方程较好地拟合.(3)在相同温度和pH下,随离子强度的提高,针铁矿对Pb~(2+)的吸附量增大.(4)在相同离子强度和pH下,针铁矿对Pb~(2+)的吸附量总体随温度升高而增大.针铁矿对Pb~(2+)的吸附是自发进行的吸热反应.(5)针铁矿吸附Pb~(2+)的过程可分为初始的快吸附和随后的慢吸附2个阶段.pH影响吸附反应快慢,随pH增大吸附速率增大;随着pH的增大,达到平衡吸附的时间缩短.吸附动力学方程用Elovich方程拟合最佳. 相似文献
644.
Shelly L. Miller Peter Scaramella Joseph Campe Cynthia W. Goss Sandra Diaz-Castillo Ed Hendrikson Carolyn DiGuiseppi Jill Litt 《Atmospheric environment (Oxford, England : 1994)》2009,43(35):5661-5667
An indoor air quality assessment was conducted on 100 homes of recent Mexican immigrants in Commerce City, Colorado, an urban industrial community north of Denver. Head of households were administered a family health survey, filled out an activity diary, and participated in a home inspection. Carbon monoxide (CO) and carbon dioxide (CO2) were measured for 24 h inside the main living area and outside of the homes. Harvard Impactors were used to collect 24-h samples of PM2.5 at the same locations for gravimetric analysis. Dust samples were collected by vacuuming carpeting and flooring at four locations within the home and analyzed by ELISA for seven allergens. Mean indoor and outdoor PM2.5 levels were 27.2 and 8.5 μg m−3, respectively. Indoor PM2.5 and CO2 were elevated in homes for which the number of hours with door/window open was zero compared to homes in which the number of hours was high (>15 h). Indoor PM2.5 levels did not correlate with outdoor levels and tended to increase with number of inhabitants, and results indicate that the source of indoor particles were occupants and their activities, excluding smoking and cooking. Mean indoor CO2 and CO levels were 1170 and 2.4 ppm, respectively. Carbon monoxide was higher than the 24-h National Ambient Air Quality Standard in 3 of the homes. The predominant allergens were cat (Fel d 1) and mouse (Mus m 1) allergens, found in 20 and 34 homes, respectively. 相似文献
645.
Isabelle Batisson Olivier Crouzet Martine Sancelme Clarisse Mallet 《Environmental pollution (Barking, Essex : 1987)》2009,157(4):1195-1201
Dissipation kinetics of mesotrione, a new triketone herbicide, sprayed on soil from Limagne (Puy-de-Dôme, France) showed that the soil microflora were able to biotransform it.Bacteria from this soil were cultured in mineral salt solution supplemented with mesotrione as sole source of carbon for the isolation of mesotrione-degrading bacteria. The bacterial community structure of the enrichment cultures was analyzed by temporal temperature gradient gel electrophoresis (TTGE). The TTGE fingerprints revealed that mesotrione had an impact on bacterial community structure only at its highest concentrations and showed mesotrione-sensitive and mesotrione-adapted strains. Two adapted strains, identified as Bacillus sp. and Arthrobacter sp., were isolated by colony hybridization methods.Biodegradation assays showed that only the Bacillus sp. strain was able to completely and rapidly biotransform mesotrione. Among several metabolites formed, 2-amino-4-methylsulfonylbenzoic acid (AMBA) accumulated in the medium. Although sulcotrione has a chemical structure closely resembling that of mesotrione, the isolates were unable to degrade it. 相似文献
646.
Sachin D. Ghude R.J. Van der A S. Fadnavis 《Environmental pollution (Barking, Essex : 1987)》2009,157(6):1873-1878
We assessed satellite derived tropospheric NO2 distribution on a global scale and identified the major NO2 hotspot regions. Combined GOME and SCIAMACHY measurements for the period 1996-2006 have been used to compute the trends over these regions. Our analysis shows that tropospheric NO2 column amounts have increased over the newly and rapidly developing regions like China (11 ± 2.6%/year), south Asia (1.76 ± 1.1%/year), Middle East (2.3 ± 1%/year) and South Africa (2.4 ± 2.2%/year). Tropospheric NO2 column amounts show some decrease over the eastern US (−2 ± 1.5%/year) and Europe (0.9 ± 2.1%/year). We found that although tropospheric NO2 column amounts decreased over the major developed regions in the past decade, the present tropospheric NO2 column amounts over these regions are still significantly higher than those observed over newly and rapidly developing regions (except China). Tropospheric NO2 column amounts show some decrease over South America and Central Africa, which are major biomass burning regions in the Southern Hemisphere. 相似文献
647.
双水相气浮浮选光度法处理环境水样中痕量土霉素残留物 总被引:1,自引:0,他引:1
建立了一种新型分离方法--双水相气浮浮选光度法,使其处理环境水样中痕量土霉紊(OTC)残留物,研究了其工作原理,并用高效液相色谱法对该方法的可靠性进行了验证.利用自制的双水相气浮浮选装置,选择四氢呋喃作亲水有机溶剂、质量分数为10%的NaCl溶液作分相剂,NaOH溶液调节pH,将Cu2+与OTC形成的疏水配合物浮选至有机相,实现OTC与水样分离.浮选完毕后,经紫外-可见分光光度法分析,线性回归方程为A=1.532×105c+0.1230(其中:A为有机相的吸光度;c为水样的OTC摩尔浓度,mol/L),相关系数为0.9998,该方法的线性范围为4.8×10-7~7.3×10-5 mol/L,OTC加标回收率为99.5%~100.1%. 相似文献
648.
CaO/SiO2对流化床焚烧飞灰熔融过程中重金属挥发的影响 总被引:1,自引:1,他引:0
对掺煤混烧的流化床焚烧飞灰熔融过程中重金属在气相(吸收率)中和固相(固定率)中的分布进行了研究,并采用HNO3-NaOH2级吸收方式对气相重金属进行了吸收.结果表明,CaO/SiO2(摩尔比)对重金属的迁移行为有重要影响,CaO/SiO2降低,Cd、Pb固定率总体呈上升趋势;2级吸收对气相重金属的吸收有限,大部分重金属主要溶解在HNO3吸收液中,但NaOH吸收液对Cr的吸收效果好于HNO3吸收液;氯对重金属的挥发有重要影响,当重金属以氯化物形式存在时,其挥发受到SiO2的限制.随着SiO2含量增加,挥发率降低. 相似文献
649.
研究采用H2O2/Fe^3+催化氧化处理高浓度含甲醛废水,探讨了双氧水和催化剂投加量、反应pH及反应温度等操作条件对处理效果的影响,并通过酸溶解回用失活催化剂。结果表明,较优的操作条件为:H2O2/COD(质量比)=2.2~2.6,Fe^3+/H2O2(摩尔比)=0.048~0.058,反应pH1.80~2.68,反应温度50℃,反应时间40 min;在上述操作条件下,甲醛去除率达到99%以上,COD去除率达到85%以上。失活的催化剂可通过稀酸溶解后循环使用,其效果与三价铁盐作催化剂的基本相同。采用H2O2/Fe^3+处理含甲醛废水具有比采用H2O2/Fe^2+较优的效果。 相似文献
650.
为了脱除CO2温室气体,提出了利用氨水土壤混合物去除CO2的新方法。分别考察了土壤颗粒粒径、CO2初始流量、氨水浓度(质量比)和温度对CO2脱除量和脱除率的影响。实验结果表明,该方法去除CO2的量较土壤物理吸附量和氨水化学吸收量的总和提高了大约15%;随着氨水浓度的增大,CO2的脱除率和脱除量都增大;随着土壤颗粒粒径和CO2初始流量的增大,CO2的脱除率和脱除量都减小;当温度由22℃升高到31℃,CO2的脱除率随着温度的升高而增大,但是继续升高温度到40℃,CO2的脱除率反而下降。 相似文献