Analysis of crater formation in buried NG pipelines: A survey based on past accidents and evaluation of domino effect

The formation of a crater by the abrupt and catastrophic rupture of a high-pressure pipeline can be highly relevant, especially when the crater uncovers other pipelines, which could undergo a domino effect with a significant increase of the consequences on people or on the environment. However, this scenario has been only partially studied in the literature. To assess the influence of the pipeline parameters on the dimensions of the resulting crater, a statistical analysis of accidental ruptures of buried natural gas pipelines that have involved the formation of a crater was carried out. Mathematical expressions are proposed to describe the proportionality relationships found, which can be very useful to support adequate separation distances in the design and construction of parallel corridors of pipelines after appropriate escalating effects are considered. Finally, detailed event trees were developed to calculate the probability of occurrence of the final outcomes, as well as the identified domino sequences, based on a qualitative and quantitative analysis of the data. The study of these accident scenarios, based on actual cases, represents a useful and needed advance in risk analysis of natural gas transportation through pipelines.     

北京市典型废弃物焚烧源2010—2017年二NFDA1英排放特征和减排效果分析

分析2010—2017年北京市三类典型废弃物焚烧源的废气二NFDA1英排放监测数据,计算排放因子和排放量,评估减排政策成效,并分析不同排放源达标排放时同类物分布特征异同和变化规律,探讨影响排放的重要因素。结果表明: 5家焚烧源平均排放浓度为 0.008～0.069 ng/m³(以TEQ计,下同),废气二NFDA1英排放因子为 0.027～1.7 μg/t,2016年向空气中排放的二NFDA1英量为 0.002 5～0.058 g；生活垃圾、危险废物和医疗废物焚烧源的低、高氯代同类物质量分数比的平均值分别为接近于 0.5、大于0.5和小于0.5,危险废物焚烧源的 ∑PCDFs、∑PCDDs质量分数比的平均值大于2； 123478-HxCDF和123678-HxCDF质量浓度接近且线性相关,具有相近的生成机理和去除效率； I-TEQ变化趋势与∑PCDFs质量分数的变化趋势基本一致,活性炭喷射和布袋除尘的去除效率是影响二NFDA1英排放的重要因素之一；危险废物焚烧源HWI1随运行时间增加排放浓度增加,而及时更换烟道管壁有助于消除“记忆效应”的不良影响。     

Enhancing the adsorption function of biochar by mechanochemical graphitization for organic pollutant removal

• Mechanochemical treatment reduced the calcination temperature for biochar synthesis. • Biochar is converted to graphite after mechanochemical treatment. • Biochar was reduced to nanoscale after mechanochemical treatment. Biochar (BC) has been extensively studied as adsorbent for the treatment of water pollution. Despite the distinct advantages, the high calcination temperature and low adsorption capacity of pristine BC limit its practical applications. Most of the former studies focused on the structure and/or surface modification to improve the adsorption capacity of BC. However, the harsh experiment conditions involved in the biochar modification limited the application in industrial level. Herein, we introduced mechanical treatment into BC preparation to reduce the calcination temperature and improve the adsorption capacity simultaneously. The results indicated that the calcination temperature was reduced and the adsorption capacity of the treated BC was improved after mechanochemical treatment. Characterization of the samples disclosed that BCs were graphitized with the particle size reduced to nanoscale after treatment. Adsorption tests indicated that the mechanochemically treated BCs showed much better removal performance of organic contaminants than that of pristine BCs. For instance, among four pristine BCs (BC600, BC700, BC800, and BC900), only BC900 has strong adsorption capacity for MB, while BC600 has low adsorption capacity (1.2 mg/g). By comparison, the adsorption capacity of MB increased greatly to 173.96 mg/g by BC600-500/1 (treated at 500 r/min for 1 hour). To optimize the mechanochemical treatment, the effects of rotation speed and agitation duration were also investigated.     

Preliminary studies on potential remediation of acid mine drainage‐impacted soils by amendment with drinking‐water treatment residuals

Mining operations result in a wide range of environmental impacts: acid mine drainage (AMD) and acid sulfate soils being among the most common. Due to their acidic pH and high soluble metal concentrations, both AMD and acid sulfate soils can severely damage the local ecosystems. Proper post‐mining management practices are necessary to control AMD‐related environmental issues. Current AMD‐impacted soil treatment technologies are rather expensive and typically not environmentally sustainable. We conducted a 60‐day bench‐scale study to evaluate the potential of a cost‐effective and environment‐friendly technology in treating AMD‐impacted soils. The metal binding and acid‐neutralizing capacity of an industrial by‐product, drinking water treatment residuals (WTRs) were used for AMD remediation. Two types of locally generated WTRs, an aluminum‐based WTR (Al‐WTR) and a lime‐based WTR (Ca‐WTR) were used. Highly acidic AMD‐impacted soil containing very high concentrations of metals and metalloids, such as iron, nickel, and arsenic, was collected from the Tab‐Simco coal mine in Carbondale, Illinois. Soil amendment using a 1:1 Al‐ and Ca‐WTR mix, applied at 5 and 10 percent rates significantly lowered the soluble and exchangeable fractions of metals in the AMD‐impacted soil, thus lowering potential metal toxicity. Soil pH increased from an extremely acidic 2.69 to a near‐neutral 6.86 standard units over the 60‐day study period. Results from this preliminary study suggest the possibility of a successful scale‐up of this innovative, cost‐effective, and environmentally sustainable technology for remediating AMD‐impacted acid sulfate soils.     

4种营养元素对水华鱼腥藻和四尾栅藻增殖的影响

以水华鱼腥藻和四尾栅藻分别作为蓝藻,绿藻代表藻种,采用均匀设计实验方法(uniform design experimentation,UDE)设计藻类AGP实验。采用通径分析法(Path Analysis,PA)对氮、磷、铁和锰在不同藻种增殖过程中的影响程度进行分析。结果表明,4种营养元素对水华鱼腥藻增殖影响的决策排序为FeTNTPMn,微量金属元素铁是影响水华鱼腥藻(蓝藻)增殖的主要因素;对四尾栅藻增殖影响的决策排序为TNTPFeMn,常量元素是影响四尾栅藻(绿藻)增殖的主要因素。联合通径分析法和逐步二次方回归分析法(QRA)建立的数学模型,可用于预判藻增殖。     

Innovative applications of subgrade biogeochemical reactors: Three case studies

Subgrade biogeochemical reactors (SBGRs) are an in situ remediation technology shown to be effective in treating contaminant source areas and groundwater hot spots, while being sustainable and economical. This technology has been applied for over a decade to treat chlorinated volatile organic compound source areas where groundwater is shallow (e.g., less than approximately 30 feet below ground surface [ft bgs]). However, this article provides three case studies describing innovative SBGR configurations recently developed and tested that are outside of this norm, which enable use of this technology under more challenging site conditions or for treatment of alternative contaminant classes. The first SBGR case study addresses a site with groundwater deeper than 30 ft bgs and limited space for construction, where an SBGR column configuration reduced the maximum trichloroethene (TCE) groundwater concentration from 9,900 micrograms per liter (μg/L) to <1 μg/L (nondetect) within approximately 15 months. The second SBGR is a recirculating trench configuration that is supporting remediation of a 5.7‐acre TCE plume, which has significant surface footprint constraints due to the presence of endangered species habitat. The third SBGR was constructed with a new amendment mixture and reduced groundwater contaminant concentrations in a petroleum hydrocarbon source area by over 97% within approximately 1 year. Additionally, a summary is provided for new SBGR configurations that are planned for treatment of additional classes of contaminants (e.g., hexavalent chromium, 1,4‐dioxane, dissolved explosives constituents, etc.). A discussion is also provided describing research being conducted to further understand and optimize treatment mechanisms within SBGRs, including a recently developed sampling approach called the aquifer matrix probe.     

基于情感思维的安全管理模式研究

为促进安全管理，提高效率与效果，对基于情感思维的安全管理进行研究，将情感思维融于安全管理，基于情感思维的定义、内涵及功能，具体分析安全管理中情感思维的功能及其功能综合作用，建立安全管理中情感思维功能作用理论模型；根据该理论模型分析情感思维驱动力及强化作用及其对安全目标实现的影响；建立基于情感思维的安全管理设计模式，最后提出优化安全管理的措施与方法，以促进安全管理的实施。研究表明:基于情感思维的安全管理研究，能较好地体现安全管理人本原理，发挥情感的能动作用，将理性融入其中与情感进行平衡，实现安全管理的优化。     

化学环境下的应力-渗流耦合对尾 矿库稳定性影响试验

通过扫描电镜（FE-SEM）、能谱分析（EDX）、X射线衍射（XRD）、LMS-30激光粒度分析等室内试验探究了尾矿库内存在的酸、碱离子对尾矿颗粒的沉降、微观形貌、物质组成以及粒径级配的影响；建立酸、碱影响下的孔隙比与渗透系数的数学关系模型，并将建立的模型用来表征尾矿库内的应力渗-流场两场耦合机制，实现代入有限元计算软件的目的。结果表明:化学因素的存在影响着尾矿颗粒的多项性状，酸性环境下尾矿颗粒发生溶蚀，部分金属元素流失；碱性环境下尾矿颗粒间生成胶结物质，孔隙出现以含氢氧化铁为主的絮状、团簇状堵塞物，改变了渗流速度；尾矿库内浸润线高度在碱性、中性、酸性环境下依次降低，而渗流速度依次升高。     

石墨相氮化碳协同UV-H_2O_2光催化降解亚甲基蓝

以三聚氰胺为前驱体,经热解—回流法制备了石墨相氮化碳(g-C3N4),采用XRD、FTIR、SEM、EDS、PL等技术对g-C_3N_4进行了表征。研究了g-C_3N_4在UV-H_2O_2体系中对废水中亚甲基蓝(MB)的光降解效果。实验结果表明,UV+g-C_3N_4催化剂+H_2O_2体系能协同降解MB,在初始MB质量浓度为20 mg/L、初始废水p H为5、废水体积为250 mL、g-C_3N_4加入量为0.10 g、H_2O_2浓度为0.4 mmol/L、反应温度为25℃的优化工艺条件下,紫外光照射70 min时MB脱色率达98.32%。g-C_3N_4催化剂具有较好的重复使用性能,使用5次后MB脱色率仍保持在95.10%。     

Aerobic treatment of swine manure to enhance anaerobic digestion and microalgal cultivation

Aerobic treatment of swine manure was coupled with anaerobic digestion and microalgal cultivation. A 14-day aerobic treatment reduced the total solid content of swine manure by >15%. Ammonia and carbon dioxide were stripped by the air supplied, and this off-gas was further used to aerate the culture of Chlorella vulgaris. The microalgal growth rates in Bristol medium and the wastewater with the off-gas increased from 0.08 to 0.22 g/L/d and from 0.15 to 0.24 g/L/d, respectively. Meanwhile, the aerobically treated swine manure showed a higher methane yield during anaerobic digestion. The experimental results were used to establish a demonstration unit consisting of a 100 L composter, a 200 L anaerobic digester, a 60 L tubular photobioreactor, and a 300 L micro-open raceway pond.