SCR脱硝系统烟道内流场优化

为了改善选择性催化还原法(SCR)催化剂上游烟气的流场、温度场和浓度场分布,基于CFD仿真分析技术,建立了整个脱硝系统三维模型,并通过优化导流板及整流格栅,使得速度标准偏差、浓度标准偏差、温度偏差、速度偏转角以及压降等性能指标都满足设计要求,在满足脱硝效率和氨逃逸率前提下,大大降低了烟气对催化剂层的冲刷,保证催化剂的使用寿命。最后,为了合理布置吹灰器,对优化结构下粉尘颗粒在烟道内的运动情况进行了仿真分析研究,为设计提供了依据。     

Effects of combinations of malathion and cypermethrin on survivability and time of metamorphosis of tadpoles of Indian cricket frog (Fejervarya limnocharis)

This study was undertaken to determine the effect of environmentally realistic concentrations of two commonly used pesticides viz., malathion and cypermethrin, using a fully 3 × 3 factorial experiments on the survivability and time of metamorphosis in a common rice paddy field frog (cricket frog) Fejervarya limnocharis under laboratory conditions. The results suggest that cypermethrin is more toxic than malathion and combinations of higher concentrations of cypermethrin (50 μg/L) with malathion (250 and 500 μg/L) are more deleterious to the survivability of tadpoles. With increasing cypermethrin concentration, the survivability of tadpole decreased (r = ?0.986, P = 0.108). But cypermethrin alone induced early metamorphosis among the surviving tadpoles. However, there was a delay in the time required for metamorphosis induced by malathion and its combination with cypermethrin. The delay in metamorphosis may indicate the altered physiological fitness of the individual. The emergent froglets will be subjected to environmental stressors like high temperature and less humidity of post-monsoon tropical climate that could enhance negative influence triggered by pesticides.     

珠江三角洲蔬菜基地蔬菜中邻苯二甲酸酯的含量特征

邻苯二甲酸酯是一类重要的环境激素类污染物。本文以气相色谱/质谱(GC/MS)联用检测技术,对珠江三角洲地区典型蔬菜生产基地蔬菜中6种邻苯二甲酸酯化合物进行测试分析。结果发现:(1)珠江三角洲地区典型蔬菜生产基地的蔬菜样品中,多数样品检测出6种邻苯二甲酸酯,总含量为0.46～12.02mg/kg。(2)基地蔬菜中单个邻苯二甲酸酯化合物的种类和含量因蔬菜种类、品种、部位和生长环境等因素而异。(3)同种类蔬菜在不同基地或同一基地不同种类蔬菜中邻苯二甲酸酯的含量分布不同。(4)大部分蔬菜中以邻苯二甲酸正二丁酯(DnBP)和邻苯二甲酸双(2-乙基己基)酯(DEHP)为主。     

Impact of Sea Level Rise on Groundwater Salinity in a Coastal Community of South Florida1

Guha, Hillol and Sorab Panday, 2012. Impact of Sea Level Rise on Groundwater Salinity in a Coastal Community of South Florida. Journal of the American Water Resources Association (JAWRA) 48(3): 510-529. DOI: 10.1111/j.1752-1688.2011.00630.x Abstract: Freshwater resources of coastal communities in the United States and world over are threatened by the rate of sea level rise. According to recent estimates by various governmental agencies and climate researchers, the global sea level rise is likely to be between 0.6 and 2.1 m by the year 2100. South Florida is a coastal community and much of its coastline is subject to sea level rise and potential impacts to wetlands and the water resources of the area. To understand what the impact of sea level rise would cause to the groundwater level and salinity intrusion, an integrated groundwater and surface water model was developed for North Miami-Dade and Broward Counties of South Florida. The model was calibrated against daily groundwater heads, base flows in canals, and chloride concentrations for a period of one year and six months. Three separate sensitivity analyses were conducted by increasing the sea level by 0.6, 0.9, and 1.22 m. Results of the simulations shows increase of groundwater heads in some areas from 4 to 15%; whereas the average relative chloride concentrations increased significantly by 100-600% in some wells. The increase in groundwater elevations and chloride concentrations varies from location of the wells and its proximity to the coast. The model results indicate that even a 0.6 m increase in sea level (which is the conservative estimate) is likely to impair the vital freshwater resources in many parts of South Florida.     

VFAs、TOC及COD作为生物除磷能力指标的探讨

在实际生活污水的处理中,研究了通过A/O运行模式对生物除磷过程中磷的变化情况及在厌氧释磷过程中COD、TOC与VFAs变化之间的关系。结果表明,在厌氧释磷过程中VFAs的变化更能准确地反映系统内释磷进程,实际生活污水中能直接用于磷释放的有机物含量占COD的13.33%,并且释放1 mg P所需VFAs为1.401 mg,此值明显低于前期研究结果。通过对COD、TOC和VFAs 3种组分的分析,可将实际生活污水中的有机底物分为3类:易生物降解含碳有机物、难降解的含碳有机物和水中存在的无机性还原物质,含量分别占COD的13.33%、31.7%和54.97%,其中只有13.33%的含量对生物释磷有直接作用,并可对实际生活污水除磷有指导意义。     

无砾石微孔管地下渗滤系统处理生活污水的中试研究

进行了无砾石微孔管地下渗滤系统处理生活污水的中试研究。基于不同土壤、不同管径、不同植物的协同效应,对比研究了不同系统处理污水中有机物、氮、磷和SS的去除效果及其影响因素。结果表明,不同土壤、不同管径及不同植物组成的系统,对生活污水中有机物、氮、磷和SS的去除效果差别较大。中试系统对COD、总磷、氨氮、总氮和SS的最佳去除率分别达到86.13%、90.20%、61.24%、65.49%和97.43%,对应的出水COD、总磷、氨氮、总氮和SS的平均浓度分别为64.29、0.69、22.13、26.19和5.56 mg/L。分析表明,进水SS浓度过高、外界温度下降等共同作用是导致系统对生活污水中NH4+-N和TN的去除率相对较低的主要原因。     

厌氧池-复合型人工湿地系统污水处理效果的季节变化

利用厌氧池-复合型人工湿地(AT-ICW)系统处理农村生活污水,探讨工艺系统不同季节对污水的处理效果。结果表明,该工艺系统春、夏、秋季对氨氮(NH4+-N)、总磷(TP)表现出稳定且较好的去除效果,去除率分别为92.8%～97.0%和56.4%～65.9%,冬季去除率相对较差,平均去除率分别为67.1%和42.5%。NO3--N的去除效果差,四季均出现积累,累积率达到71.5%～342.9%。系统春、夏季对总氮(TN)去除效果较好,去除率为57.3%～68.9%,秋、冬季去除效果相对较差,为24.5%～35.8%。系统夏季COD去除效果好,平均去除率达到78.3%,冬、春季去除效果较差,为37.8%～43.5%。各项污水排放指标均达到城镇污水处理厂污染物排放一级A类标准。AT-ICW系统不仅处理效果好,而且运行费用低,适用于农村分散型生活污水处理。     

超强静磁场对染料脱色菌Escheriehia coli的acpD基因的影响

将大肠杆菌E.coli ATCC8739置于12.0 T超强静磁场(ultra-strong static magnetic field,SMF)中进行处理,获得了磁场处理0.5、1、2、4和8 h的菌株E.coli-SMFn(n=0.5、1、2、4、8)。在37℃、pH 7、静置的条件下,菌株对偶氮染料AR14(I.C.Acid Red 14)的脱色结果指出,当反应进行到4、6和8 h时,E.coli-SMF8的脱色效率分别为18%、55%和96%,远高于E.coli ATCC8739的3%、19%和50%,表明SMF作用显著地增强了菌株的脱色效率。基因组DNA提取、PCR扩增、分子克隆以及基因测序的实验结果进一步表明,全部6例E.coli ATCC8739菌株的偶氮还原酶基因(acpD)序列均与GenBank中报道的完全一致;而E.coli-SMF8菌株的acpD-SMF8核酸序列中缺失了第99位的胞嘧啶。该缺失突变不仅使acpD-SMF8的核酸序列与acpD的存在显著不同,同时得到了具新活性中心的偶氮还原酶AzoR-SMF8。这个新的活性中心具有更强的黄素(FMN)结合能力,因此使该酶与偶氮染料的亲和力大大增加,促进了脱色效率的提高。     

城镇污水处理厂NPR工艺低温运行的效能分析

介绍了天津市某城镇污水处理厂NPR工艺的特点及运行状况。通过对污水厂的运行监测数据分析,研究了该工艺在低温条件下处理城镇生活污水时的脱氮除磷效果。结果表明:NPR工艺具有一定的优异性,它能在降低能耗的前提下使系统COD和SS的去除率进一步降低,出水能达到中水回用标准,有利于污水的再生利用;低温影响NPR系统的硝化及反硝化率,低温下有机物的去除更易受到有机负荷的影响;温度对生物去除SS,COD和TP的效果影响不大,对NH3-N及TN的去除效果影响比较明显。低温下污水处理厂COD、SS、NH3-N、TN、TP的平均去除率分别为72.1%、94.9%、67.5%、55.1%、66.5%。     

直播稻田渗漏水磷素动态变化及渗漏流失潜力研究

通过田间实验,对太湖流域丹阳地区直播水稻田不同施磷水平下渗漏水磷素动态变化特征及流失潜力进行了研究。结果表明,施磷能明显提高地下60cm以上深度土层渗漏水磷的含量。各土层渗漏液总磷浓度随土层深度的增加呈下降趋势。随着施磷量的增加,稻田渗漏水磷素含量也会随之增加。土壤磷素发生渗漏流失的土壤表层Olsen-P含量的"突变点"change-Point为25.17 mg/kg。当土壤中的Olsen-P浓度小于25.17mg/kg时,20～40cm土层渗漏水中TP浓度基本上不随土壤Olsen-P浓度的变化而变化,但当土壤中Olsen-P大于25.17mg/kg时,20～40cm土层渗漏水中TP浓度会大量增加,且土壤中的Olsen-P每增加10 mg/kg,渗漏水TP将增加0.21 mg/L。稻田当季累计土壤磷素渗漏流失负荷为1.02 kg/ha,占当季施磷量的2.80%。