室内有毒易爆气体的检测

随着城市生活水平的提高,室内装修装饰日益普及.各种新材料的引入,使得室内的各种有害气体总量日益增加.长期生活在这样的环境下,会对人体健康产生极为不利的影响.居民生活用煤气,在给人们生活带来便利的同时,作为一种可燃性、有毒气体,也具有极强的危害性.因此,研制一种能检测多种有害气体的实用仪器,具有很大的应用价值.本仪器为便携式多功能仪器,采用可充电电池供电,可以检测ppb的挥发性气体,显示气体浓度值,也可检测煤气,并具有声光报警功能.     

煤矿火灾烟气流动传播过程仿真研究

煤矿发生火灾后会生成大量有毒气体并产生火风压,烟气在火灾动力的影响下出现状态紊乱,研究煤矿火灾烟气流动传播过程对控制火情有着重要意义。基于国内外研究现状,对燃烧及风流特点进行分析,建立了煤矿火灾烟气流动数学模型,并利用CFD软件进行仿真。研究表明:无通风工况下的烟气为对称流动;随着风速增加,出口处温度降低,烟气向风流入口处的流速减小。     

Full-scale blending treatment of fresh MSWI leachate with municipal wastewater in a wastewater treatment plant

Fresh leachate, generated in municipal solid waste incineration (MSWI) plants, contains various pollutants with extremely high strength organics, which usually requires expensive and complex treatment processes. This study investigated the feasibility of blending treatment of MSWI leachate with municipal wastewater. Fresh MSWI leachate was pretreated by coagulation–flocculation with FeCl₃ 2 g/L and CaO 25 g/L, plate-and-frame filter press, followed by ammonia stripping at pH above 12. After that, blending treatment was carried out in a full-scale municipal wastewater treatment plant (WWTP) for approximately 3 months. Different operational modes consisting of different pretreated leachate and methanol addition levels were tested, and their performances were evaluated. Results showed that throughout the experimental period, monitored parameters in the WWTP effluent, including COD (<60 mg/L), BOD₅ (<20 mg/L), ammonium (<8 mg/L), phosphorus (<1.5 mg/L) and heavy metals, generally complied with the Chinese sewage discharged standard. Under the experimental conditions, a certain amount of methanol was needed to fulfill TN removal. An estimation of the operation cost revealed that the expenditure of blending treatment was much lower than the total costs of respective treatment of MSWI leachate and municipal wastewater. The outcomes indicated that blending treatment could not only improve the treatability of the MSWI leachate, but also reduce the treatment cost of the two different wastewaters.     

The value of virtual conferencing for ecology and conservation

The objectives of conservation science and dissemination of its research create a paradox: Conservation is about preserving the environment, yet scientists spread this message at conferences with heavy carbon footprints. Ecology and conservation science depend on global knowledge exchange—getting the best science to the places it is most needed. However, conference attendance from developed countries typically outweighs that from developing countries that are biodiversity and conservation hotspots. If any branch of science should be trying to maximize participation while minimizing carbon emissions, it is conservation. Virtual conferencing is common in other disciplines, such as education and humanities, but it is surprisingly underused in ecology and conservation. Adopting virtual conferencing entails a number of challenges, including logistics and unified acceptance, which we argue can be overcome through planning and technology. We examined 4 conference models: a pure‐virtual model and 3 hybrid hub‐and‐node models, where hubs stream content to local nodes. These models collectively aim to mitigate the logistical and administrative challenges of global knowledge transfer. Embracing virtual conferencing addresses 2 essential prerequisites of modern conferences: lowering carbon emissions and increasing accessibility for remote, time‐ and resource‐poor researchers, particularly those from developing countries.     

Metal distribution characteristic of MSWI bottom ash in view of metal recovery

Bottom ash is the major by-product of municipal solid waste incineration(MSWI), and is often reused as an engineering material, such as road-base aggregate. However, some metals(especially aluminum) in bottom ash can react with water and generate gas that could cause expansion and failure of products containing the ash; these metals must be removed before the ash is utilized. The size distribution and the chemical speciation of metals in the bottom ash from two Chinese MSWI plants were examined in this study, and the recovery potential of metals from the ash was evaluated. The metal concentrations in these bottom ashes were lower than that generated in other developed countries. Specifically, the contents of Al,Fe, Cu and Zn were 18.9–29.2, 25.5–32.3, 0.7–1.0 and 1.6–2.5 g/kg, respectively. Moreover,44.9–57.0 wt.% of Al and 55.6–75.4 wt.% of Fe were distributed in bottom ash particles smaller than 5 mm. Similarly, 46.6–79.7 wt.% of Cu and 42.9–74.2 wt.% of Zn were concentrated in particles smaller than 3 mm. The Fe in the bottom ash mainly existed as hematite, and its chemical speciation was considered to limit the recovery efficiency of magnetic separation.     

港口罢工对周边空气质量的影响

港口污染物的排放浓度极大地影响着周边的空气质量,以2013年3月28日香港国际集装箱码头发生的罢工事件为契机来探究港口运作短暂的瘫痪对周边空气质量的影响。首先,进行污染物之间的相关性分析确定影响本次罢工事件的污染物主要为NO_2、NO_x、SO_2以及O_3。其次,基于罢工前、罢工期间以及罢工后污染物排放的浓度变化,进行横向对比发现罢工期间的污染物确实有一定程度的减少。再次,利用纵向对比排除四季带来的影响探究不同年份同一阶段污染物浓度的变化情况评估罢工期间的空气质量。最后,以NO_2为例建立预测模型对罢工期间的NO_2浓度进行预测,根据实际值与预测值之间的差异来说明罢工影响了NO_2的预测趋势。这项研究主要强调港口空气质量对整个环境的影响,在一定程度上说明政府实施政策的有效性,为政府提供了决策支持,同时也要注重污染物之间的相互转化作用对环境的影响。     

燃煤电厂烟塔合一排烟风洞试验与数值模拟对比分析

近年来,燃煤电厂烟塔合一烟气排烟对近距离环境影响的不确定性,使其在国内的推广过程受到一定限制。准确判断烟塔合一排烟的环境影响,对于我国现有燃煤电厂烟气污染物的排放有着巨大的工程价值和明显的现实意义。利用国家环境保护某重点实验室中风洞试验平台,对燃煤电厂烟塔合一烟气污染物在近距离的扩散和传输行为,进行物理风洞试验以及数值模拟计算,并进行对比分析。结果表明:德国Austal2000模式的浓度预测并不精确;数值风洞也有其差异性,而物理风洞的结果在很大程度上符合现有的理论及国内工程实际。     

流化床焚烧含盐苯胺废液的NOx排放特性

在流化床焚烧实验装置上进行含盐苯胺(C6H5NH2)废液的焚烧实验研究,用IMR-IMR2800P废气分析仪对焚烧尾气成分进行了在线监测,考察了焚烧工艺条件对NOx排放浓度的影响规律.结果显示:采用分级燃烧工艺和提高焚烧温度,可以降低NOx浓度;增大进料速率却导致NOx排放浓度的增加.当过剩空气系数(α)低于1.0时,NOx排放浓度随着α的增大急剧上升;大于1.1时,NOx排放浓度随α增加而减小.苯胺废液高温焚烧时添加氯化钠能降低NOx排放.     

氨对垃圾焚烧飞灰浸出特性的影响及地球化学模拟

垃圾焚烧飞灰可能因为选择性非催化还原法(SNCR)脱硝过程中氨泄漏、垃圾携带的渗滤液受热挥发等原因而吸附氨.本研究中采用人为添加氨水,在pH为3.66～12.44范围内,研究氨对飞灰中溶解性有机碳(DOC)和重金属浸出的影响,并利用地球化学模拟软件Visual MINTEQ从金属化学形态分布上分析氨对飞灰浸出的影响机制.结果表明,DOC在pH>9和有高浓度氨(≥1 357 mg·L-1)存在时,其浸出量大幅增加,而在浸出液中氨的水平不高于537 mg·L-1时则受氨的影响很小;在pH<6时,飞灰中各金属主要以自由态的金属离子和金属-氯络离子形态大量溶出,且受氨的影响较小;而在pH为8～12的碱性环境中和氨浓度较高时(≥3 253 mg·L-1),氨与金属生成了可溶性的金属-氨配合物,能显著增加Cd、Cu、Ni、Zn的浸出,且在pH=9附近时浸出量达到最大值,但氨对Al和Pb的浸出影响甚微;在pH>12时,Cd、Cu、Ni、Zn主要以羟基金属离子形式存在.在氨浓度为3 253 mg·L-1时,通过利用Visual MINTEQ模拟浸出值与试验数据的对比,发现Al、Pb、Zn的浸出主要由溶解/沉淀模型控制,而Cd、Cu、Ni由溶解/沉淀模型和表面吸附反应模型同时控制,且Visual MINTEQ模型能较好地预测飞灰中Al、Cu、Pb、Zn的浸出特性.     

Pollutant emission characteristics of rice husk combustion in a vortexing fluidized bed incinerator

Rice husk with high volatile content was burned in a pilot scale vortexing fluidized bed incinerator. The fluidized bed incinerator was constructed of 6 mm stainless steel with 0.45 m in diameter and 5 m in height. The emission characteristics of CO, NO, and SO2 were studied. The effects of operating parameters, such as primary air flow rate, secondary air flow rate, and excess air ratio on the pollutant emissions were also investigated. The results show that a large proportion of combustion occurs at the bed surface and the freeboard zone. The SO2 concentration in the flue gas decreases with increasing excess air ratio, while the NOx concentration shows reverse trend. The flow rate of secondary air has a significant impact on the CO emission. For a fixed primary air flowrate, CO emission decreases with the secondary air flowrate. For a fixed excess air ratio, CO emission decreases with the ratio of secondary to primary air flow. The minimum CO emission of 72 ppm is attained at the operating condition of 40% excess air ratio and 0.6 partition air ratio. The NOx and SO2 concentrations in the flue gas at this condition are 159 and 36 ppm, which conform to the EPA regulation of Taiwan.