反应器热爆炸风险分析模型的构建

从风险的角度开展化工安全管理与决策。基于能量转移论,综合运用化工工艺的热风险评估和保护层分析(LOPA)方法,在对各类典型事故预防控制措施的有效性分析基础上,选择化工工艺过程中的绝热温升(ΔTad)表征反应器热爆炸的严重度,采用保护层分析得到的事故发生频率表征反应器热爆炸的发生可能性,构建了适用于反应器热爆炸的风险分析模型。在运用该模型对甲苯一段硝化间歇反应器的热爆炸风险进行分析的过程中,给出了相应的风险决策方案,验证了模型的可行性。     

Anaerobic phenanthrene biodegradation with four kinds of electron acceptors enriched from the same mixed inoculum and exploration of metabolic pathways

Anaerobic phenanthrene biodegradation enriched process was described in detail. The enriched bacterial communities were characterized under four redox conditions. The enriched archaeal communities were stated under high percentage conditions. Relatively intact pathways of anaerobic phenanthrene biodegradation were proposed. Polycyclic aromatic hydrocarbons (PAHs) are widespread and persistent contaminants worldwide, especially in environments devoid of molecular oxygen. For lack of molecular oxygen, researchers enhanced anaerobic zones PAHs biodegradation by adding sulfate, bicarbonate, nitrate, and iron. However, microbial community reports of them were limited, and information of metabolites was poor except two-ring PAH, naphthalene. Here, we reported on four phenanthrene-degrading enrichment cultures with sulfate, bicarbonate, nitrate, and iron as electron acceptors from the same initial inoculum. The high-to-low order of the anaerobic phenanthrene biodegradation rate was the nitrate-reducing conditions>sulfate-reducing conditions>methanogenic conditions>iron-reducing conditions. The dominant bacteria populations were Desulfobacteraceae, Anaerolinaceae, and Thermodesulfobiaceae under sulfate-reducing conditions; Moraxellaceae, Clostridiaceae, and Comamonadaceae under methanogenic conditions; Rhodobacteraceae, Planococcaceae, and Xanthomonadaceae under nitrate-reducing conditions; and Geobacteraceae, Carnobacteriaceae, and Anaerolinaceae under iron-reducing conditions, respectively. Principal component analysis (PCA) indicated that bacteria populations of longtime enriched cultures with four electron acceptors all obtained significant changes from original inoculum, and bacterial communities were similar under nitrate-reducing and iron-reducing conditions. Archaea accounted for a high percentage under iron-reducing and methanogenic conditions, and Methanosarcinaceae and Methanobacteriaceae, as well as Methanobacteriaceae, were the dominant archaea populations under iron-reducing and methanogenic conditions. The key steps of phenanthrene biodegradation under four reducing conditions were carboxylation, further ring system reduction, and ring cleavage.     

Source attribution for mercury deposition with an updated atmospheric mercury emission inventory in the Pearl River Delta Region,China

Estimated anthropogenic Hg emission was 11.9 tons in Pearl River Delta for 2014. Quantifying contributions of emission sources helps to provide control strategies. More attentions should be paid to Hg deposition around the large point sources. Power plant, industrial source and waste incinerator were priorities for control. A coordinated regional Hg emission control was important for controlling pollution. We used CMAQ-Hg to simulate mercury pollution and identify main sources in the Pearl River Delta (PRD) with updated local emission inventory and latest regional and global emissions. The total anthropogenic mercury emissions in the PRD for 2014 were 11,939.6 kg. Power plants and industrial boilers were dominant sectors, responsible for 29.4 and 22.7%. We first compared model predictions and observations and the results showed a good performance. Then five scenarios with power plants (PP), municipal solid waste incineration (MSWI), industrial point sources (IP), natural sources (NAT), and boundary conditions (BCs) zeroed out separately were simulated and compared with the base case. BCs was responsible for over 30% of annual average mercury concentration and total deposition while NAT contributed around 15%. Among the anthropogenic sources, IP (22.9%) was dominant with a contribution over 20.0% and PP (18.9%) and MSWI (11.2%) ranked second and third. Results also showed that power plants were the most important emission sources in the central PRD, where the ultra-low emission for thermal power units need to be strengthened. In the northern and western PRD, cement and metal productions were priorities for mercury control. The fast growth of municipal solid waste incineration were also a key factor in the core areas. In addition, a coordinated regional mercury emission control was important for effectively controlling pollution. In the future, mercury emissions will decrease as control measures are strengthened, more attention should be paid to mercury deposition around the large point sources as high levels of pollution are observed.     

Effects of intercropping with floricultural accumulator plants on cadmium accumulation in grapevine

Environmental Science and Pollution Research - Grapevine (Vitis vinifera L.) intercropping with floricultural cadmium (Cd) accumulator plants (Helianthus annuus L., Cosmos sulphureus Cav., Cosmos...     

煤矿照度对人反应时间和可靠度的影响研究

煤矿综采工作面狭窄,工作环境昏暗,照明环境普遍不好,是近年来井下事故多发的重要因素之一。针对目前煤矿综采工作面存在的照度问题,通过控制光照时间和操作难度,利用舒尔特表测算反应时间和操作可靠度,使用SPSS20. 0和Excel进行数据处理,设计试验组和对照组来进行对比试验。结果表明,1)从反应时间来看,0～25 min,试验组平均反应时间的变化趋势与对照组相反,被试者的注意力先下降后上升; 25～55 min,被试者逐渐适应低照度环境,反应时间也在逐渐缩短;被试者在低照度条件下操作55 min后,反应时间随光照时间增加而大幅度增加,超过劳动时间临界值后,视觉疲劳度迅速增加,反应急速减慢,从而可能导致安全事故的发生,影响生产效率,此时应合理安排工人休息。2)从操作难度来看,在简单及正常操作难度时,试验组和对照组操作可靠度变化比较接近,表明低照度条件对一般操作的可靠度影响不明显;在极难操作难度时,低照度条件对可靠度影响明显,在井下生产过程中,低照度环境下应尽量避免安排复杂的机械化操作。3)反应时间与光照时间呈二次函数关系,通过建立回归方程量化了两者的关系,为以后合理安排煤矿工人劳动休息时间提供了理论依据。     

垃圾填埋场渗滤液地下原位脱氮技术综述

氨氮是城市垃圾厌氧填埋过程中产生的常见的污染物。由于氨氮的持久性和生物毒性,生活垃圾填埋场渗滤液中氮的脱除已引起了人们的高度关注。文中结合国内外的研究现状的基础,论述了厌氧渗滤液回灌、强制通风好氧填埋、准好氧填埋和生物反应器填埋四种垃圾渗滤液原位脱氮处理技术的原理、技术特点、工程投资、运行成本以及处理效果等;指出了垃圾填埋场渗滤液原位脱氮技术的未来研究重点:填埋场内脱氮机理和脱氮速率的深入研究、工艺控制优化研究以及生物反应器填埋的实际应用设计研究。