Kinetics of selective catalytic reduction of NO by NH3 on Fe-Mo/ZSM-5 catalyst

The catalyst of Fe-Mo/ZSM-5 has been found to be more active than Fe-ZSM-5 and Mo/ZSM-5 separately for selective catalytic reduction (SCR) of nitric oxide (NO) with NH3. The kinetics of the SCR reaction in the presence of O2 was studied in this work. The results show that the observed reaction orders were 0.74-0.99, 0.01-0.13, and 0 for NO, O2 and NH3, respectively, at 350-450℃. And the apparent activation energy of the SCR was 65 kJ/mol on the Fe-Mo/ZSM-5 catalyst. The SCR mechanism was also deduced. Adsorbed NO species can react directly with adsorbed ammonia species on the active sites to form N2 and H2O. Gaseous O2 might serve as a reoxidizing agent for the active sites that have undergone reduction in the SCR process. It is also important to note that a certain amount of NO was decomposed directly over the Fe-Mo/ZSM-5 catalyst in the absence of NH3.     

利用紫外预处理加强氯苯的生物滴滤净化

试验采用主波长为185nm的低压汞灯为紫外光源、醚型聚氨酯海绵(PU-foam)为填料的紫外-生物滴滤塔联合装置净化氯苯废气.进气氯苯浓度为600mg·m-3、停留时间分别为92、69和46s时,联合装置的平均去除率分别达到99%、95%和80%;最大去除负荷达到59.6g·(m3·h)-1;联合装置和单独生物滴滤塔生物膜形成时间分别为20d和27d;联合装置的抗冲击能力较好,停留时间缩短至30s,联合装置去除效率可达75%以上,高于单独生物滴滤塔的去除效率(25%).对紫外-生物滴滤塔联合装置机制初步探讨表明,紫外氧化氯苯形成了水溶性较好的可生物降解的物质,降低生物滴滤塔氯苯的处理负荷,同时紫外辐照过程中产生的O3能有效地控制生物滴滤塔内微生物的过量生长,从而维持整个装置的最佳运行状态.     

2008年南黄海西部浒苔暴发区有机碳的分布特征及浮游植物的固碳强度

根据2008-08-09～2008-08-13在南黄海西部绿潮(浒苔)暴发区取得的溶解有机碳(DOC)、颗粒有机碳(POC)和颗粒氮(PN)的分析数据,结合同步获得的水文环境要素资料,研究了该区域有机碳的分布特征、来源、影响因素以及浮游植物的固碳强度.结果表明,DOC的浓度范围为1.55～3.22mg/L,平均值为2.44mg/L;POC的浓度范围为0.11～0.68mg/L,平均值为0.27mg/L.DOC与POC的分布特征基本一致,呈现近岸高,外海低;表层高,底层低的趋势.POC与TSS的相关分析表明,POC与TSS整体上呈显著正相关,表明TSS的浓度和来源是控制POC浓度高低的重要因素.通过建立POC与PN的一元线性回归模型,估算了样品中PIN的含量.扣除样品中PIN的影响后,沿岸大部分海域POC/PON的平均值8,结合POC/Chl-a比值,表明沿岸海域POC主要是海洋有机质来源,并且存在降解有机物,这可能是调查期间处于绿潮暴发后期,部分浒苔开始腐烂被降解所致.应用初级生产力估算的浮游植物固碳强度的结果表明,南黄海西部绿潮(浒苔)暴发区浮游植物的固碳强度变化范围为167～2017mg/(m2·d),平均为730mg/(m2·d),该区域日固碳量达到2.95×104t.换算至整个黄海,日固碳量为28.03×104t.     

基于活性污泥模型的污水COD组分划分方案研究

活性污泥数学模型(ASM)在污水处理厂的成功应用与进水组分的正确划分密切相关.从标准化和定量化的角度利用3个批式试验开发了COD组分划分方案及Matlab计算程序.该方案在上海2个污水处理厂的测定结果表明,曲阳污水厂进水COD中含有8.1%±1.6%的易生物降解组分SS、6.3%±2.2%的溶解性惰性组分SI、45.5%±3.5%的慢速生物降解组分XS、31.1%±2.1%的颗粒性惰性组分XI和9.0%±1.1%的异养菌组分XH.而白龙港污水厂进水COD中含有11.1%±2.2%的SS、9.9%±2.0%的SI、38.9%±10.7%的XS、23.3%±9.8%的XI和16.9%±1.8%的XH.与曲阳污水厂相比,白龙港污水厂进水COD中XS和XI含量偏低,而XH/COD值则明显偏高,表明长距离管道输送会显著影响COD组分浓度.     

巢湖周围池塘氮、磷和有机质研究

巢湖周围池塘众多,根据池塘位置和地表径流补给差异,池塘可以分为村庄内池塘、毗邻村庄池塘和农田区域池塘(远离村庄的池塘).本研究采集了巢湖周围136口池塘上覆水和沉积物样品,调查巢湖周围池塘中氮、磷以及有机质污染现状.结果表明,池塘上覆水中总氮、氨氮、硝态氮、亚硝态氮、总磷、溶解态磷和COD平均含量分别为2.53、0.65、0.18、0.02、0.97、0.38和51.58mg·L-1;池塘沉积物中总氮、氨氮、硝态氮、亚硝态氮、总磷、无机磷、有机磷和烧失量平均含量分别为1575.36、35.73、13.30、2.88、933.19、490.14、414.75mg·kg-1和5.44%;90%以上的池塘总氮、总磷含量达到或超过富营养化水平.位于村庄内的池塘上覆水和沉积物中总氮和氨氮的含量显著高于位于农田区域的池塘.上覆水和沉积物中无机氮表现为:氨氮硝态氮亚硝态氮.池塘上覆水和沉积物中有机质与总氮、总磷之间存在显著的正相关性.池塘中氮、磷和有机物质主要为陆源性输入,池塘位置和径流补给方式明显影响其中的氮、磷和有机质含量.通过截留径流中的氮、磷和有机质,池塘能够有效减少进入巢湖的营养盐含量.     

辽河口湿地沉积物硝化细菌及硝化作用研究

2009年6月和8月,采用现场培养和实验室模拟培养相结合的方法对辽河口湿地表层沉积物硝化细菌数量、硝化速率及影响因素进行了研究.结果表明,辽河口湿地表层沉积物氨氧化细菌(ammonia-oxidizing bacteria,AOB)数量6月在0.54×104～5.69×104个.g-1之间,平均值为(2.21±2.32)×104个.g-1,8月在1.90×104～7.90×104个.g-1之间,平均值为(3.61±2.87)×104个.g-1;沉积物潜在硝化速率6月在9.72～16.45 mmol.(m2.h)-1之间,平均值为(12.54±3.14)mmol.(m2.h)-1,8月在14.66～24.62 mmol.(m2.h)-1之间,平均值为(18.71±4.21)mmol.(m2.h)-1;净硝化作用速率6月(S1站)为0.41 mmol.(m2.h)-1,8月在0.20～0.53 mmol.(m2.h)-1之间,平均值为(0.35±0.16)mmol.(m2.h)-1.潜在硝化速率显著高于净硝化速率,AOB数量、净硝化作用速率和潜在硝化作用速率均表现为8月高于6月,芦苇根际效应对硝化作用有促进作用.通过SPSS 13.0软件统计分析,表明影响辽河口湿地表层沉积物硝化作用的主要环境因子有上覆水NH 4+-N浓度和沉积物pH、有机质、总氮(TN)、总磷(TP)、NH 4+-N含量以及AOB数量(p0.05),其中上覆水NH 4+-N浓度和沉积物总磷(TP)、NH 4+-N含量对硝化作用影响较大,是辽河口湿地硝化作用影响的关键因素.根据研究结果估算辽河口湿地沉积物硝化作用每天可以将1.14×105kg的NH 4+-N转化为NO 3--N,对河口湿地氮的循环具有重要意义.     

Review of the remediation strategies for soil water repellency

Many regions of the world are predicted to experience water scarcity due to more frequent and more severe droughts and increased water demands. Water use efficiency by plants can be negatively affected by soil water repellency (SWR). It is timely to review existing techniques to remedy SWR. Ideally remediation addresses the origins of a problem. However, the fundamental mechanisms of how and why SWR develops are still poorly understood. In this review it was hypothesized that SWR occurs where the balance of input-decomposition of organic matter is impaired, due to either increased input or decreased decomposition rates of hydrophobic substances. Direct and indirect strategies to remedy SWR were distinguished. While direct remediation aims at abolishing the causes of SWR, indirect strategies seek to manage sites with SWR by treating its symptoms. The 12 reviewed strategies include applying surfactants, clay, slow-release fertilizers, lime, and fungicides, bioremediation of SWR through stimulating earthworms, choosing adapted vegetation, irrigation, cultivation, soil aeration and compaction. Some of the techniques have been applied successfully only in laboratory experiments. Our review highlights that it is not straightforward to cure SWR based on easily measurable and site-specific soil and vegetation properties, and that long-term, large-scale field experiments are required to improve the understanding of the evolution of SWR as cornerstone to develop cost-effective and efficient remediation strategies. We also identified current research gaps around the diagnosis and prevention of SWR.     

活性炭纤维电极电还原产H2O2的实验研究

利用活性炭纤维作为阴极,比较了活性炭纤维电极和石墨板电极产H2O2的浓度,并对影响活性炭纤维电极产H2O2的因素(pH、电流密度和电解质浓度)进行了研究.研究发现,活性炭纤维电极电还原产生H2O2的浓度远大于石墨板电极.当实验在pH=3.00、电流密度8.89 mA/cm2和电解质(Na2SO4)浓度0.05 moL/...     

邻苯二甲酸二丁酯暴露对雄性大鼠生精细胞功能影响

观察不同剂量的邻苯二甲酸二丁酯(DBP)对成年大鼠生精细胞损伤、端粒酶和端粒酶逆转录酶(TERT)表达影响.对40只健康雄性SD大鼠随机分成4组,分别为500mg·kg-1·d-1、250mg·kg-1·d-1、50mg·kg-1·d-1 3个染毒组和1个对照组,灌胃量为5mL·kg-1体重,灌胃法连续给药6周.对体重...     

基于CFD的内构件强化内循环流化床流场结构分析

针对流化床内部流体结构的复杂性和缺乏有效放大设计理论的问题,以漏斗型导流内构件强化的内循环流化床的气液运动为研究对象,利用欧拉-欧拉双流体模型构建了能描述其复杂流动的CFD数学模型,通过宏观流场、气含率分布、液体速度分布解析内构件对气液混合传质的作用原理.数值模拟结果表明:双流体模型能较好地揭示流化床内气液流场结构,流...