A/DAT-IAT生物膜法处理高含盐废水

以含盐量为60 000mg/L(以NaCl计)的模拟工业废水为研究对象,利用A/DAT-IAT生物膜反应器,研究A/DAT-IAT工艺对投加悬浮填料后高含盐废水的处理,并以CODCr、NH4 -N、PO43--P等作为指标评价处理效果.试验结果表明,在总水力停留时间(HRT)为13 h、pH=7,5、25℃条件下,进水ρ(CODCr)、ρ(NH4 -N)和ρ(PO43--P)分别为907.4～1 210.0 mg/L、86.2～99.7 mg/L和3.6～5.1 mg/L.CODCr、NH4 -N和PO43--P的平均去除率分别为73.9%、38.6%和93.5%,平均出水SS为198 mg/L,其中CODCr和PO43--P的去除效果较好.研究表明,A/DAT-IAT生物膜法较其他活性污泥法有了较大的提高.     

城市天然气工程环境风险评价

结合广州、深圳、东莞、佛山等城市的天然气工程情况,对城市天然气工程的环境风险评价进行了讨论,并采用穆尔哈斯(Moorhowse)和普里恰特(Prichard)提出的热辐射预测模式和爆炸冲击波预测模式对城市天然气工程进行了风险评价.结果表明,如果发生天然气泄漏并引起火灾,假设在10 min以内,城市门站、调压站和城市高中压管道的火球对建筑物和设备的严重损害范围( A 级)最远距离分别为35.8 m、18.0 m和28.7 m,爆炸冲击波严重损害范围( C1 级)分别为距事故处54.8 m、27.8 m和44.4 m.最后从城市门站、调压站选址及输气管道选线、安全防范距离、作业过程中的风险控制与管理以及事故应急对策四方面提出了风险事故的防范措施与对策.     

基于生态分区的我国湖泊营养盐控制目标研究

为更好地控制我国湖泊的富营养化水平,在五大湖泊生态分区的基础上,对不同生态分区的100个湖泊总氮(TN)、总磷(TP)、TN/TP与叶绿素a(Chl-a)的关系进行了分析,进而提出了不同生态分区的湖泊营养盐控制目标.结果表明,五大湖泊生态分区中,东北湖区富营养化水平最低,华北湖区富营养化水平最高,近几年五大湖区湖泊富营养水平呈上升趋势.从TN、TP对五大生态分区湖泊Chl-a浓度的影响看,TP是东北和华北湖区湖泊藻类生长的限制性营养盐,而TN和TP同时是中东部、云贵和蒙新湖区湖泊藻类生长的限制性营养盐.从TN/TP判断,在TN/TP<10的湖泊中,除华北湖区外的其他4个湖区湖泊Chl-a均受TN显著影响;TP仅对东北、蒙新湖区湖泊的Chl-a有显著影响.在TN/TP>17的湖泊中,除蒙新湖区外的其他4个湖区湖泊Chl-a均受TP显著影响,而在中东部、云贵和蒙新湖区,TN对Chl-a也有显著影响.在10相似文献   

新安江流域土地利用结构对水质的影响

以新安江上游流域为研究区域,用该流域2010年5月TM遥感影像图作为底图,通过实地野外调查获取了新安江流域的土地利用图.运用ArcGIS的水文、空间分析功能,将流域划分为8个子流域,并分析各子流域的土地利用结构.根据2010年1～12月的水质监测数据,分析TN、TP、高锰酸盐指数、NH4+-N、粪大肠菌群的时空变化特征,以及与土地利用结构之间的定量关系.结果表明,TN和NH4+-N有明显的时间变化特征,为枯时期>丰水期>平水期,而其他几种指标没有明显的时间变化.在空间上,整体上呈现出渔梁、浦口污染最为严重.流域内土地利用结构与水质之间的相关关系表现为:耕地、水体、建筑用地起源作用,林地、草地起汇作用.在年度上看,耕地对TN、NH4+-N、高锰酸盐指数影响最大,草地对TP影响最大;不同水期上,枯水期和丰水期,对各指标影响最大的土地利用类型为耕地,在平水期,对TN、TP、粪大肠菌群影响最大的土地利用类型分别为耕地、草地、林地.     

Experimental investigation of the performance of modified expanded graphite powder doped with zinc borate in extinguishing sodium fires

Sodium is the main cooling medium in the circuit of fourth-generation nuclear reactors, and its leakage constitutes a severe fire hazard because of its high chemical activity. In this study, expandable graphite (EG), which is a traditional sodium fire-extinguishing agent, was modified with zinc borate (ZB) as an intercalator, and the modified EG_ZB was characterized. Moreover, the effectiveness of the modified EG_ZB in extinguishing sodium fires was tested using a self-developed fire-extinguishing experimental device. This study's results indicated that EG, EG_ZB had a smaller particle size, higher thermal stability, higher fire-extinguishing speed, and lower powder mass consumption than EG. During the fire-extinguishing process, ZnO decomposed by ZB captured free radicals and inhibited the combustion reaction. Furthermore, B₂O₃ was adsorbed on the surface of the EG layer, which strengthened covering and asphyxiation. The findings of this study provide crucial information for effectively controlling fires caused by active metals and metallo-organic compounds.     

A data-driven narratives skeleton pattern recognition from accident reports dataset for human-and-organizational-factors analysis

Accidents in the process industry involve several interacting factors, including human and organizational factors (HOFs). A long-standing obstacle to HOFs analysis is lack of data. Accident reports are an essential data source to learn from the past and contain HOFs-related data, but they are usually unstructured text in a not standardized format. Some studies have explored the extraction of information automatically from accident reports based on Natural Language Processing (NLP) techniques. However, they were not dedicated to HOFs. Risk communication is considered an essential pillar in safety and risk science. This research develops a HOFs-focused risk communication framework based on the NLP techniques that can support risk assessment and mitigation. The proposed approach automatically extracts the target groups oriented “Who, When, Where, Why” (4Ws) information from accident reports.This framework was applied to explore the eMARS database. The results show that the “4Ws” skeleton of narratives has appreciated performance in pattern recognition and holistic information analysis. The graphical representation interfaces are designed to display the features of HOFs-related accidents, which can better be communicated to the sharp-end operators and decision-makers.     

Numerical investigation of powder aerosolization in a mining rock dust dispersion chamber

We have conducted numerical simulations of dust dispersion within the NIOSH Rock Dust Dispersion Chamber. The apparatus consists of a low-speed background ventilation flow down a long box in which is placed a tray containing a rock dust powder. A nozzle upstream of the tray introduces a short pulse of a turbulent horizontal jet flow just above the powder surface. We have utilized an incompressible Reynolds-Averaged Navier-Stokes k-ω model for the turbulent flow; particles are incorporated within a one-way Euler-Lagrangian formalism. The Rock Dust Dispersion Chamber ventilation flow exhibits a recirculation zone just above the powder-containing tray. Aerosolization proceeds via the interplay of the jet pulse flow with the background recirculation flow. The air flow is not well-mixed. The aerosolized dust is convected as a concentration cloud downstream towards the detection zone. For larger particles, gravitational settling depletes the convected cloud, so the instrument behaves as a horizontal elutriator. The instrument is robust with respect to misalignment of the jet nozzle. However, reduced streamwise drift velocity allows mixing to disperse the optically detected dust cloud concentration pulse. Our large particle simulation results compare favorably with published experimental results for large, polydisperse calcium carbonate rock dust.     

Simulation of scenario characteristics of LPG tank explosion accident and its contribution to emergency planning: A case study

Leakage and explosion of hazardous chemicals during road transportation can cause serious building damage and casualties, and adoption of highly-efficient emergency rescue measures plays a critical role in reducing accidental hazards. Considering a liquefied petroleum gas (LPG) transport tanker explosion accident that occurred in Wenling, Zhejiang Province, China on June 13, 2020 as example, this study proposes a risk assessment framework. This framework recreates the leakage and explosion of the accident process using FLACS v10.9, suggests plans for evacuation, describes the rescue areas of different levels, and explores the influence of environmental factors on the evacuation and rescue areas. The results show that simulated and predicted distributions of fuel vapour cloud concentration and explosion overpressure can provide a reference basis for rapid rescue activities; the characterization of the dynamic effects of wind speed, wind direction, and temperature with respect to the evacuation and rescue areas can be used as theoretical support for on-site adjustment of rescue forces. The role of obstacles can prevent the expansion of the evacuation areas under low wind-speed conditions, and the presence of highly congested obstacles determines the level of the rescue area. The results obtained are important for the risk analysis and the development of emergency rescue measures in case of explosion accidents associated with transportation of hazardous chemicals on high-hazard and high-sensitive road sections.     

A disaster scene simulation system in 3D for oil transmission stations: Design and implementation

The disaster scene in three-dimensional (3D) plays a crucial role in disaster emergency management and risk communication of oil transmission stations. However, existing research for the disaster scene mainly focuses on reproducing the disaster environment and rarely predicts the damage state of the disaster-affected object. This paper proposes an object-oriented modeling method that utilizes a multilevel decomposition pattern for disaster scenes. This method combines earthquake vulnerability assessment with 3D visualization technology to predict and characterize the damage state of critical infrastructure in oil transmission stations. To enhance earthquake risk perception, a simulation system is designed and developed, which allows for the construction of virtual scenes and quick simulation of disaster scenes in 3D. The case application shows that the system improves the 3D modeling efficiency of disaster scenes and enhances public awareness of earthquake risks. The simulation system can provide technical support for seismic mitigation planning and emergency management decision-making at oil transmission stations and has good application prospects.     

长大区间隧道抽出式串联通风机排烟能力实验研究*

为实现有效通风以降低隧道火灾带来的损失和伤亡,依托青岛市地铁8号线大洋站至青岛北站区间隧道,建立线性比尺为1∶15的隧道通风排烟模型实验系统,针对通风机串联单抽,围绕3种通风机频率匹配组合,测定单机的变频频率值、电功消耗、排烟道与行车道的断面平均风速以及右侧行车道静压。研究结果表明:在相同功率消耗下,不同频率匹配的串联通风机排烟效果存在差异;针对此差异,利用气体挡烟墙性能及其计算欧拉数值比较发现,风井近端的通风机频率较大时,下游对污染气流的抵抗力更强,拥有更好的排烟效果。研究结果可为隧道火灾提供更有效率的防灾救灾数据支持,并从欧拉数方面为研究隧道临界风速提供新角度。