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在研究氢氧化镁混凝特性的基础上,复配氯化镁和硫酸铝作为混凝剂,以高岭土配水水样为研究对象,运用iPDA在线监测技术对混凝过程絮体形成进行监测,探讨了单独使用氯化镁和硫酸铝以及二者复配使用的混凝效果和絮体特性,确定复配使用的各种条件。结果表明,对于浊度20 NTU,pH 11.5的高岭土配水水样,氯化镁、硫酸铝最佳投加量分别为7.2 mg/L(Mg2+计)和3 mg/L(Al3+计);硫酸铝跟氯化镁复配使用时,先投加硫酸铝,间隔30 s后投加氯化镁,混凝效果较好;在镁离子最佳投加量7.2 mg/L时,铝和镁最佳质量比在1∶3~1∶2之间;镁铝复配时其FI值明显大于单独作用时,即絮体尺寸大小:二者复配硫酸铝氯化镁,而且复配条件下Zeta电位值在零电势左右浮动,浮动范围小,更利于聚集沉淀;镁铝复配时发生了协同效应,弥补了单独使用氯化镁混凝过程的不足。 相似文献
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以木糖为碳源采用间歇培养方式,对木糖厌氧发酵产酸进行研究。考察木糖浓度和初始pH值对木糖厌氧产酸的影响。结果表明,随着木糖浓度的增加,总产酸量得到提高,但木糖利用率却呈现下降的趋势。当木糖浓度为5 g/L时,其利用率为100%,15 g/L时利用率为73.9%,此时挥发性脂肪酸(VFAs)为9.22 g/L。木糖的分批投加可有效促进产酸,尤其是促进乙酸浓度的提高。pH为5.0和6.0左右时,VFAs主要成分为乙酸和丁酸;而pH为7.0~9.0时,乙酸含量明显增高,在pH值为8.0的条件下乙酸含量占总VFAs的80.1%。在pH=8.0时经过8 d左右的发酵,VFAs浓度可达9.34 g/L。 相似文献
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采用掺Al-TiO2作为改性剂制备改性膨润土,考察了微波辐射功率、辐射时间、TiO2改性剂用量、铝盐掺杂量、pH值对微污染水中COD和NH4-N去除效果的影响。实验表明,微波辐射功率为460 W,辐射时间为8 min,TiO2改性剂用量为1.3 mmol/g,铝盐掺杂量为0.2 mmol/g为最佳制备条件。pH值为6.0,改性膨润土投加量为40 mg/L,沉淀时间为30min时,对微污染水中初始浓度15 mg/L的COD和5 mg/L的NH4-N去除率分别达到92%和59%以上。 相似文献
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水溶性离子液体对甲苯的吸收效果及影响因素 总被引:1,自引:0,他引:1
《环境工程学报》2017,(3)
选择3种水溶性离子液体(十二烷基咪唑氯盐(DDMIM Cl)、十二烷基咪唑硝酸盐(DDMIM NO_3)、十二烷基咪唑双氰胺盐(DDMIM DCA))作为研究对象寸模拟曱苯废气进行吸收实验,研究了吸收液的吸收性能、甲苯浓度、吸收液浓度、进气气速以及盐度等因素对吸收效果的影响以及加热蒸馏法对吸收液的再生与甲苯回收的可行性。结果表明:不同的离子液体对甲苯的吸收率不同J)DMIM DCA的吸收效果最好在质量分数为5%时,初始吸收率达到98%,饱和吸收量为53.39 mg·L~(-1),而DDMIM CKDDMIM NO_3对甲苯的初始吸收率在92%左右,饱和吸收量分别为33.60,37.01 mg·L~(-1);甲苯饱和吸收量与吸收液浓度、甲苯进气浓度呈正相关,与进气气速、含盐度呈负相关;传质系数与甲苯进气浓度、进气气速以及含盐度呈正相关,与吸收液浓度呈负相关;采用加热蒸馏法进行甲苯回收及吸收液再利用时用苯的回收效率达到85%~90%且甲苯的饱和吸收量随着重复利用次数的增加而基本保持不变。因此利用离子液体溶液处理甲苯废气理论上是可行的。 相似文献
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采用置换沉积法制备了纳米钯/铝双金属催化剂,氢解还原去除水相中难降解有毒有机物3-氯酚(3-CP),考察了溶液pH、钯负载量、纳米钯/铝双金属投加量、反应温度对脱氯效果的影响并解析相关反应机制。结果表明:(1)初始pH 3.0时,沉积液中93.25%(质量分数,下同)~96.67%的钯可有效负载于铝材上。(2)在pH为3.0、纳米钯/铝双金属投加量为2g/L、钯负载量为1.16%(质量分数)、反应温度为25℃下降解初始摩尔浓度为0.389mmol/L的3-CP,反应终了时脱氯率在99%以上。利用纳米钯/铝双金属降解氯代有机污染物具有高效低耗的优势,在实际应用上具有较好的前景。 相似文献
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牡蛎壳粉末投加UASB反应器的运行特性 总被引:1,自引:0,他引:1
采用牡蛎壳粉末作为UASB反应器的辅助介质,探讨了牡蛎壳钙盐的溶出特性,系统考察了运行期中牡蛎壳粉末添加方式、进水有机负荷、水力停留时间等因素对反应器出水COD、碱度与pH的影响,分析了污泥比产甲烷活性变化。结果表明,当初始pH从5到9变化时,牡蛎壳粉末溶出Ca2+浓度为40~65 mg/L,平衡pH稳定在7.7~8.0;当进水COD负荷从3.4 kg/(m3·d)逐渐增至7.0 kg/(m3·d)、牡蛎壳粉末投加量从1.5 g/d逐渐增至3.2 g/d时,与未投加的反应器相比,投加牡蛎壳粉末反应器的启动周期缩短了10%左右,COD去除率与比产甲烷活性分别提高了13.3%和22%。投加牡蛎壳粉末可有效提供碱度,加快污泥的颗粒化进程。 相似文献
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镁盐复合混凝剂应用于活性染料印染废水脱色的实验研究 总被引:2,自引:0,他引:2
采用镁盐与亚铁盐混合复配对活性染料印染废水进行脱色处理.考察该复合混凝剂的组分配比、pH值和投加量对脱色率的影响,并与单一组分混凝剂的脱色效果作对比,同时初步分析了复合混凝剂的脱色机理.结果表明:复合混凝剂MgSO4-FeSO4·7H2O的脱色效果明显优于单一组分,表现出显著的协同效应;对于80 mg/L的活性黑KN-B印染废水(色度为1000倍),在复合混凝剂投加量为556 mg/L、pH值在10.9左右时,脱色率可以达到99.07%;主要脱色机理表现为镁盐和亚铁盐在高pH值的环境下共沉淀生成氢氧化物絮状物吸附溶液中的染料分子一起沉降.该吸附主要为电中和吸附.吸附等温线符合Langmuir方程,复合吸附剂的饱和吸附量达1.1614 g/g. 相似文献
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氧化镁烟气脱硫反应特性研究 总被引:7,自引:2,他引:5
利用实验室规模的鼓泡式反应装置,对比了碳酸钙、氧化镁和氧化镁/硫酸镁脱硫剂的反应活性,证实脱硫液中高浓度硫酸镁的存在是保证镁法脱硫效率高于钙法的重要因素,并考察了硫酸镁浓度、脱硫剂(氧化镁)浓度、烟气量、SO2浓度和吸收液温度等因素对脱硫效率的影响。结果表明,脱硫反应可以根据pH分为2个不同阶段;反应过程中脱硫效率随着硫酸镁浓度的增加而显著升高;烟气量增加将会导致脱硫效率有所下降;入口SO2浓度升高,脱硫效率下降;氧化镁浓度、温度对脱硫效率影响不显著。结合实验现象进行推断,氧化镁脱硫的反应过程受SO2在气液两相界面的传质扩散和其水解产物在液相的扩散控制。 相似文献
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《Atmospheric environment (Oxford, England : 1994)》2001,35(13):2375-2393
Unsteady absorption characteristics of sulfur dioxide by an atmospheric water droplet in motion are predicted numerically and analyzed theoretically to recognize the physical mass transport processes inside an aerosol droplet, which is frequently encountered in the atmosphere. Considering the absorption of sulfur dioxide by a droplet in cloud or fog with various velocities, three different Reynolds numbers, viz., Reg=0.643, 1.287, and 12.87 are studied and compared with each other. The results indicate that for the Reynolds number of 0.643, sulfur dioxide always penetrates toward the droplet centerline throughout the entire absorption period. This is due to the mass transfer dominated by diffusion along the radial direction. In contrast, when the Reynolds number is 12.87, the strength of the vortex motion inside the droplet is strong enough. It results in that, most of the time the concentration contours parallel the streamlines and the lowest SO2 concentration is located at the vortex center. As a consequence, the diffusion distance is reduced by a factor of three and the absorption time for the droplet reaching the saturated state is shortened in a significant way. With regard to an intermediate Reynolds number such as 1.287, a two-stage mass transfer process can be clearly identified. In the first stage, it is dominated by one-dimensional diffusion, in which over 50% sulfur dioxide is absorbed before the saturated state is reached. In the second stage, the vortex motion mainly controls the mass transfer. However, the contour core is inconsistent with the vortex center. This is because the characteristic time of mass diffusion is in a comparable state with that of droplet internal circulation. The present study elucidates that the strength of a droplet's internal motion plays a vital role in determining SO2 absorption process. 相似文献
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以城市污水处理厂剩余污泥作为处理介质,土著嗜酸氧化硫硫杆菌(Acidithiobacillus thiooxidans,A.thiooxi-dans)为主要沥滤微生物,采用序批式生物沥滤装置,就投加150~725μm的不同粒径元素硫对沥滤的酸化效果、硫酸根产率和重金属去除效果的影响进行了研究。结果表明,在元素硫投配量为3 g/L,曝气强度为1.0 L/(min.L)的条件下,元素硫粒径在165~215μm范围减小时能显著改善污泥酸化速度、提高酸化程度和硫酸根产率。底物元素硫的最佳粒径为165μm,此时沥滤体系pH下降速率为0.85个pH单位/d,硫酸根的产率为454.9 mg/(L.d),沥滤6 d后污泥中高浓度重金属Cu、Zn、Cd的去除率达到70.3%、81.2%、87.8%. 相似文献
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B. I. Chevone D. E. Herzfeld S. V. Krupa A. H. Chappelka 《Journal of the Air & Waste Management Association (1995)》2013,63(7):813-815
Acid sulfate aerosol (500 μg/m3) had no effect on soybean or pinto bean after a single 4-h exposure. However, visible Injury and chlorophyll loss occurred when plants were sequentially exposed to acid aerosol and ozone (380 μg/m3) for 4 h. In yellow poplar seedlings exposed to ozone (200 μg/m3), sulfur dioxide (210 μg/m3) and simulated rain solutions (pH 5.6, 4.3 and 3.0) for 6 weeks, root dry weight, leaf area increase, mean relative growth rate and unit leaf rate decreased linearly with pH in ozone-treated plants. However, unit leaf rate and mean relative growth rate increased linearly in response to sulfur dioxide as solution acidity increased. Ambient wet and dry sulfate concentrations appear insufficient to directly impact vegetation. 相似文献
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A re-survey of acid-sensitive lakes in Ireland (initial survey 1997) was carried out during spring 2007 (n = 60). Since 1997, atmospheric emissions of sulfur dioxide and deposition of non-marine sulfate (SO4
2−) in Ireland have decreased by ~63 and 36%, respectively. Comparison of water chemistry between surveys showed significant
decreases in the concentration of SO4
2−, non-marine SO4
2−, and non-marine base cations. In concert, alkalinity increased significantly; however, no change was observed in surface
water pH and total aluminum. High inter-annual variability in sea salt inputs and increasing (albeit non-significant) dissolved
organic carbon may have influenced the response of pH and total aluminum (as ~70% is organic aluminum). Despite their location
on the western periphery of Europe, and dominant influence from Atlantic air masses, the repeat survey suggests that the chemistry
of small Irish lakes has shown a significant response to reductions in air pollution driven primarily by the implementation
of the Gothenburg Protocol under the UNECE Convention on Long-Range Transboundary Air Pollution. 相似文献
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The effects of simultaneous large acidic and alkaline airborne pollutants on forest soil 总被引:3,自引:0,他引:3
Haapala H Goltsova N Pitulko V Lodenius M 《Environmental pollution (Barking, Essex : 1987)》1996,94(2):159-168
The effects of air pollutants on soil were studied in Scots pine (Pinus sylvestris L.) forests near the boundary of Russia and Estonia. The study area is characterized by large amounts of acidic and basic pollutants, mainly sulphur dioxide (SO(2)) and calcium (Ca). Several variables were measured in different horizons of the podzolic soil polluted by emissions from local sources in areas of several thousands of square kilometers. Alkalinization dominates the processes in the soil, since sulphur is absorbed only in small quantities and Ca is much better absorbed. Ca content in humus horizon may rise even to 100 000 mg kg(-1) and the pH of originally very acidic soil may rise to 8.3. Total aluminum (Al) content was high in the heavily polluted plots, since emissions contain much Al. On the other hand, the exchangeable Al was very low in these alkaline sites. A larger quantity of exchangeable Al occurred farther from the pollutant sources, even though total Al in these plots was low. These plots had acidic soils in which Al is in exchangeable form. Due to the neutralizing effect of acidic and basic pollutants, forest damage in the study area was not as serious as might be supposed. Complicated pollutant situations must be taken into consideration when pollution-caused environmental protection measures are planned. It is not reasonable to reduce only SO(2) emissions, but necessary to lower the basic emissions at the same time. 相似文献
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Effect of alkalinity on the performance of a simulated landfill bioreactor digesting organic solid wastes 总被引:6,自引:0,他引:6
This study investigated the effects of alkalinity on the anaerobic treatment of the organic solid wastes collected from the kitchen of Engineering Faculty in Dokuz Eylul University, Izmir, Turkey and the leachate characteristics treated in three simulated landfill anaerobic bioreactors. All of the reactors were operated with leachate recirculation. One reactor was operated without alkalinity addition. The second reactor was operated by the addition of 3 g l-1 d-1 of NaHCO3 alkalinity to the leachate and the third reactor was operated by the addition of 6 g l-1 d-1 NaHCO3 alkalinity to the leachate. After 65 d of anaerobic incubation, it was observed that the chemical oxygen demand (COD), volatile fatty acids (VFA) concentrations, and biochemical oxygen demand to chemical oxygen demand (BOD5/COD) ratios in the leachate samples produced from the alkalinity added reactors were lower than the control reactor while the pH values were higher than the control reactor. The COD values were measured as 18900, 3800 and 2900 mg l-1 while the VFA concentrations were 6900, 1400 and 1290 mg l-1, respectively, in the leachate samples of the control, and reactors containing 3 g l-1 NaHCO3 and 6 g l-1 NaHCO3 after 65 d of anaerobic incubation. The total nitrogen (TN), total phosphorus (TP) and ammonium nitrogen (NH4-N) concentrations in organic solid waste (OSW) significantly reduced in the reactor containing 6 g l-1 NaHCO3 by d 65. The values of pH were 6.54, 7.19 and 7.31, after 65 d of anaerobic incubation, respectively, in the aforementioned reactors results in neutral environmental conditions in alkalinity added reactors. Methane percentage of the control, reactors containing 3 g l-1 NaHCO3 and 6 g l-1 NaHCO3 were 37%, 64% and 65%, respectively, after 65 d of incubation. BOD5/COD ratios of 0.27 and 0.25 were achieved in the 3 and 6 g l-1 NaHCO3 containing reactors, indicating a better OSW stabilization. Alkalinity addition reduced the waste quantity, the organic content of the solid waste and the biodegradation time. 相似文献