我国制浆造纸行业二噁英来源及排放情况

利用联合国发布的“二噁英和呋喃排放识别和量化标准工具包（2013版）”进行估算,2014年我国制浆造纸行业二噁英排放总量约为406.68 g TEQ,其中向水体排放20.08 g TEQ,向残余物排放20.99 g TEQ,较2005年分别下降了44.4%和42.2%,较2009年分别下降了11.2%和8.4%。元素氯漂白工艺为向水体和残余物排放二噁英的主要源头。目前,我国木浆生产全部采用无元素氯（ECF）和全无氯（TCF）漂白工艺,但仍有72%的非木浆生产采用元素氯漂白工艺,因此,开展非木浆清洁生产技术研究十分必要。此外,提高我国废纸回收率,改善废纸质量,改进废纸再生清洁生产工艺,也将对减少制浆造纸产品中二噁英的循环量有重要意义。     

垃圾焚烧炉二次燃烧的数值模拟

针对城市生活垃圾焚烧发电的排放问题,以重庆市某垃圾焚烧炉为原始模型,采用计算流体动力学(CFD)方法对炉膛内气体的二次燃烧过程进行了数值模拟.利用标准k-ε湍流模型对气相湍流运输进行了模拟,并利用Monte-Carlo 热辐射模型计算了辐射传热特性,获得了当施加不同边界条件时炉膛内气体的温度场、浓度场以及气体在炉膛内的停留时间分布等,并对其抑制二噁英产生的效果进行了评价.结果表明:进口边界混合气体中CO的含量和气体速度对燃烧效果有重要影响.当CO含量为5%、气体速度为1.58m/s时,燃烧效果较好,并能有效抑制二噁英类剧毒物质的产生.通过对垃圾焚烧炉二次燃烧的数值模拟与仿真,可获得和预测炉膛内气体燃烧的状况,并为焚烧炉的设计和改进提供一定的参考.     

Additional exposure of the Irish adult population to dioxins and PCBs from the diet as a consequence of the 2008 Irish dioxin food contamination incident

In 2008, the discovery of elevated levels of dioxins and PCBs in a porcine fat sample taken as part of the national residues monitoring programme led to the detection of a major feed contamination incidence in the Republic of Ireland. To estimate additional exposure to dioxins and PCBs due to the contamination incident, all data associated with the contamination incident were collected and reviewed. An exposure model was devised that took into account the proportion of contaminated product reaching the final consumer during the contamination incident window and which utilised all additional information that became available after the incident occurred. Exposure estimates derived for both dioxins and PCBs showed that the body burden of the general population remained largely unaffected by the contamination incident and only approximately 10% were exposed to elevated levels of dioxins and PCBs. Whilst this proportion of the population experienced quite a significant additional load to the existing body burden, the estimated exposure values do not suggest that these would be associated with adverse health effects, based on current knowledge. The exposure period was also limited in time to approximately 3 months, following the recall of contaminated meat immediately on detection of the contamination.     

危险废物焚烧处置中二恶英的产生及控制

介绍了二恶英的结构和性质,分析了其产生原因,指出危险废物的焚烧处理是二恶英的重要排放源。分析了二恶英在危险废物焚烧处理过程中的产生过程,根据该过程提出了一系列较为有效的措施来抑制二恶英的生成,并结合工程实例说明该措施可以有效减少二恶英的排放,值得进一步在危险废物焚烧处置工程中推广。     

低成本去除电弧炉废气中二恶英的方案

钢铁工业承受着不断降低工艺废气中所含二恶英和其他有害排放物的巨大压力。在20世纪90年代初,奥钢联开始研究用于烧结厂和电弧炉的新型废气净化系统并显著提高了净化效率。对新方案及其实际应用效果进行介绍。     

铁矿石烧结过程二恶英排放的影响因素研究

通过采用2水平7因素正交试验设计（L₈（2⁷））的烧结锅试验,研究了影响烧结机二恶英排放的相关因素。EP灰、BF灰和外购氧化铁皮是二恶英排放的主要"促进剂",而生石灰是二恶英排放的"抑制剂"。对各影响因素而言,二恶英的排放模型并不是加和模型而是乘积模型,对应于添加5%EP灰、5%BF灰、5%外购氧化铁皮和2%生石灰时,它们的系数分别为28、4、4和0.7。至于操作条件,包括料层高度、焦粉含量、气体流速和废气补燃器的开/关对二恶英排放没有显著影响。这些事实支持了烧结过程二恶英的合成为化学反应控制。     

对我国再生铝工业环境问题的认识

再生铝原料品位高、易再生,基建投资、生产成本、能源消耗和污染物排放量均远低于原生铝,国家产业政策已将其列入鼓励产业;我国铝矿产资源并不丰富、人均占有量只有世界平均水平的1／10,大力发展再生铝工业是我国发展循环经济和实现铝工业可持续发展的必然选择。但再生铝工业既不是“绿色产业”,也不应是“洋垃圾处理工厂”。     

香港迪士尼基建工程二恶英污染土处理技术

在香港迪士尼基建工程范围内,香港政府进行了环境影响评估研究,报告显示船厂用地的泥土含有害物质,其中约37 000m3的泥土,受到二恶英污染。通过经济及安全等方面的比选,采用非直接热力解吸法处理二恶英污染土。采用此方法处理结果达到了剩余二恶英量不超过百亿分之一,取得了良好的经济效益和社会效益。     

Aryl Hydrocarbon Receptor (AhR) Activation by 2,3,7,8-Tetrachlorodibenzo-p-Dioxin (TCDD) Dose-Dependently Shifts the Gut Microbiome Consistent with the Progression of Non-Alcoholic Fatty Liver Disease

Gut dysbiosis with disrupted enterohepatic bile acid metabolism is commonly associated with non-alcoholic fatty liver disease (NAFLD) and recapitulated in a NAFLD-phenotype elicited by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in mice. TCDD induces hepatic fat accumulation and increases levels of secondary bile acids, including taurolithocholic acid and deoxycholic acid (microbial modified bile acids involved in host bile acid regulation signaling pathways). To investigate the effects of TCDD on the gut microbiota, the cecum contents of male C57BL/6 mice orally gavaged with sesame oil vehicle or 0.3, 3, or 30 µg/kg TCDD were examined using shotgun metagenomic sequencing. Taxonomic analysis identified dose-dependent increases in Lactobacillus species (i.e., Lactobacillus reuteri). Increased species were also associated with dose-dependent increases in bile salt hydrolase sequences, responsible for deconjugation reactions in secondary bile acid metabolism. Increased L. reuteri levels were further associated with mevalonate-dependent isopentenyl diphosphate (IPP) biosynthesis and o-succinylbenzoate synthase, a menaquinone biosynthesis associated gene. Analysis of the gut microbiomes from cirrhosis patients identified an increased abundance of genes from the mevalonate-dependent IPP biosynthesis as well as several other menaquinone biosynthesis genes, including o-succinylbenzoate synthase. These results extend the association of lactobacilli with the AhR/intestinal axis in NAFLD progression and highlight the similarities between TCDD-elicited phenotypes in mice to human NAFLD.     

二恶英污染--发展造纸工业必须解决的战略性问题

以国内外对二恶英污染严重性的认识和防治措施,提出了二恶英污染是发展造纸工业必须解决的战略性问题。