内循环厌氧反应器多相流流场的三维数值分析简

利用数值模拟的方法,引入欧拉双流体多相流模型及标准k-ε紊流模型,模拟计算内循环厌氧反应器的三相流三维流场,并通过改变污泥颗粒密度及进水流量,针对固相流速及固含率的变化情况,分析条件的改变对流场的影响。研究结果表明,应用数值模拟方法可以获得内循环厌氧反应器内的流场特征;污泥颗粒密度及进水流量的改变对于反应器内污泥颗粒的流速及分布的均匀性有较为明显的影响。模拟结果对反应器的应用及优化设计具有一定的参考价值。     

连续流砂过滤器深度处理市政污水的中试研究

采用好氧/缺氧连续流砂过滤器中试实验研究深度处理北京某污水处理厂二级出水。实验结果表明,当连续流砂过滤器好氧段聚合氯化铝投量为20 mg/L,缺氧段碳源投量为32 mg/L时,COD、NH+4-N、TN和TP的平均去除率分别为34.77%、86.54%、66.94%和84.10%,最终出水均达到北京市新(改、扩)建城镇污水处理厂排放A标准(DB11/890-2012)。克隆文库法分析石英砂表面生物膜中的细菌群落结构表明,其优势菌群为β-proteobacteria,其中大部分能以废水中碳源为电子供体还原硝酸盐。     

Effects of cadmium on the activities of photosystems of Chlorella pyrenoidosa and the protective role of cyclic electron flow

Cadmium (Cd) shows high toxicity to aquatic microalgae. Many studies showed that Cd inhibited activities of photosystem II (PSII) but the effects of heavy metals on photosystem I (PSI) and cyclic electron flow (CEF) were still controversial and unclear. The effects of CdCl₂ on the activities of PSI, PSII and CEF in Chlorella pyrenoidosa was measured simultaneously in the present study. In presence of 200 μM of Cd, ultrastructure of some cells was strongly modified. Cd exposure led to decrease of the activities of photosynthetic oxygen evolution and respiration. PSII was more sensitive to Cd treatment than PSI. Cd treatment showed significant inhibition on the photochemical quantum yield and electron transport rate of PSII. Cd increased the quantum yield of non-light-induced non-photochemical fluorescence quenching, indicating the damage of PSII. The activity of PSI showed tolerance to Cd treatment with concentration less than 100 μM in the experiment. Linear electron flow (LEF) made significant contribution to the photochemical quantum yield of PSI of the untreated cells, but decreased with increasing Cd concentration. The contribution of CEF to the yield of PSI increased with increasing Cd concentration. The activation of CEF after exposure to Cd played an essential role for the protection of PSI.     

地震液化流滑震害

通过地震液化的震害调查,从土种类、地形条件和坡度、液化土壤的赋存状况、地震能量和流滑的时间与空间分布等方面,简要总结了液化流滑的震害特征和规律,初步分析了液化引起流滑发生的条件、规模、剧烈程度、坡体运动规律以及流滑产生的破坏形式,分析了影响流滑的因素,可供进一步研究等参考。     

Monitoring morphological and vegetation changes and flow events in dryland river channels

Monitoring of impacts of floods in river valleys of dryland regions has become important with the onset and threats of desertification and is likely to become even more vital with predictions of increased effects of climate and land use change. It is also needed in order to conform to requirements of the EU Water Framework Directive. Monitoring in such regions sets particular challenges. This paper explains a system of low-cost monitoring of changes in morphology, vegetation and sediment cover in channels and valley floors of ephemerally flowing streams. It has been applied in SE Spain for 10 years and has proved very effective. In particular, the use of simple crest-stage recorders for measuring flow height and the use of real-time differential GPS for rapid and accurate survey and for relocating points have proved very valuable. Part of the monitoring is focused on the interaction of plants and channel processes. Small changes in and around vegetation associated with flow events have been detected by a combination of quadrat surveys and cross-profiling of the channel. A range of flow events has been measured over the period of monitoring, demonstrating their differing effects and the varying sensitivity and responsiveness of different sites. The sporadic occurrence of flood events in such an environment means that a strategy of monitoring several sites and of continuation over many years has great benefits.     

西部开发中的泥石流问题

西部地区的青、甘、陕、川、滇、黔、新、藏、宇、桂、内蒙和重庆等12个省区市内都有泥石流分布,已查明的泥石流沟计15500余条,受泥石流危害或威胁的县级以上政府驻地城镇逾百座,一场泥石流致死百人以上的灾害点达23个,泥石流及其灾害是西部大开发中必须面临的生态环境问题之一,城市建设、公路和铁路等交通建设、水利建设,西气和西电东送工程建设等西部大开发的重点领域,,在开发建设中都将要遇到泥石流问题,吸取以往这类建设中抗御泥石流灾害的经验与教训,对于减轻泥石流灾害和保障西部大开发顺利进行具有现实意义。     

泥石流灾情评估指标体系

泥石流灾情评估指标体系的建立应满足适用性、完备性、可比性、综合性和系统性原则,而指标的选取还应在一定的要求下确定。依据上述原则,在泥石流灾情网络分析结果的基础上,建立了评估指标体系的结构层次模型,进而对各类灾情评估指标进行了分析,确定出评估泥石流灾情的具体指标和因子。最后建立了以成灾度为目标层,经济损失,社会影响,环境损害为准则层。评估指标和评估因子为指标层的泥石流灾情评估指标体系。     

流动注射对氨基二甲基苯胺光度法测定水体中的硫化物

为了克服分光光度法反应时间难以控制引起的方法精密度、准确度不高的弱点,采用流动注射技术与分光光度法相结合的方法,用微机化流动注射分析仪准确控制时间,优化了实验条件,建立了测定痕量硫化物的流动注射分光光度方法。分析速度每小时80次,擎一质量浓度在0．02～0．8mg／L与吸光度A具有良好的线性关系。方法直接测定海水和鱼塘水中的硫化物获得满意的结果,回收率分别为100．28％和97．13％。     

流动注射分析仪在测定水体总氮中的实验研究

总氮是衡量水质富营养化的重要指标。用传统方法分析需经过高压消解,温度和时间难以控制,且手工操作复杂、费时,误差大,影响监测结果。本文用流动注射法,以QuickChem 8000流动注射仪为平台,通过大量的精密性、准确性和实样比对实验来研究其在水质总氮测定中的应用,再用数理统计的方法（F检验、t检验）从理论上验证该方法的可行性。     

多点网格流速在线测量方法研究

烟气流速是CEMS监测的重要参数,其准确性直接关系到污染物排放总量。由于受安装场地的限制,同一烟道截面流速分布不均匀,单点测量难以真实反映断面流真实流速。根据某电厂流速监测现状,结合Fluent软件对烟道流场进行模拟分析和手工网格采样理论,提出多点网格在线流速测量方法,明显提高流速测量精度和代表性。