错流膜生物反应器水力清洗特性研究

采用外压管式聚砜－聚丙烯腈共混超滤膜进行错流膜生物反应器水力清洗特性研究,结果表明,清洗时采用高膜面流速、低操作压力和限制透过液对流传递作用有利于错流膜生物反应器通量的恢复,这符合膜藏去除过程中的传质机理;适宜的膜面流速应稍大于临界流速ｖｋ＝１．９２ｍ／ｓ,清洗时间应控制在１０ｍｉｎ,适宜的清洗操作压力为０．０７ＭＰａ。     

化学质量平衡法在水体污染物源解析中的应用

化学质量平衡法（ＣＭＢ）是大气污染物源解析的主要方法之一。本实验模拟静肪水全点源恒流排放的条件,各污染物在水中的扩散行为,建立扩散经验模型来验证化学质量平衡法是否适用于水全污染物的源解析。做污染物浓度－距离曲线可预测各污染物的扩散行为;由同一污染源中污染物扩散方程的比较来确定污染源“成分谱”随扩散过程的变化,再由受体的污染物浓度便可求出每一污染源对该受体的贡献度,除极个别点外,污染物浓度实验值与预     

关于臭氧—靛蓝二磺酸钠分光光度法（GB／T15437—95）问题探讨

本文就臭氧—靛蓝二磺酸钠（ Ｉ Ｄ Ｓ）分光光度法（ Ｇ Ｂ／ Ｔ１５４３７－ ９５）中存在的问题进行了深入探讨,指出其臭氧摩尔质量（ １２ Ｏ３）为２４００ｇ／ｍ ｏｌ,而不是１２００ｇ／ｍ ｏｌ,从而纠正了方法中的错误。     

紫外分光光度法对苯酚、苯胺和苯甲酸的同时测定方法的研究

利用紫外分光光度法的吸光度加和性原理,对苯酚、苯胺和苯甲酸的同时测定方法进行了研究.通过调整待测物质溶液的pH值,可以使其分光光度法的吸收峰发生红移(或蓝移),从而有利于确定该物质的最佳吸收波长.对苯酚、苯胺和苯甲酸的分析测定表明,在碱性介质中该系列化合物的吸光度具有较好的加和性,其相对误差在10%～15%之间,适于多组分同时测定.本方法的苯酚、苯胺和苯甲酸的线性范围均为0～70 mg/L;加标回收率分别为95.8%～107.8%,97.6%～117%和93.7%～108.5%,测定2组水样时的相对标准偏差分别为1.84%、3.20%,2.71%、1.06%和2.61%、5.10%.     

Tracking Chinese newspaper coverage of elephant ivory through topic modeling

Mass media worldwide has contributed to increasing awareness of the illegal wildlife trade and its significant impact on wildlife conservation. We used mass media coverage as a proxy for macro-level public opinion to analyze the media framing of elephant ivory in 6394 Chinese newspaper articles published from 2000 to 2021 and thus determine the effects of wildlife policies on public opinion. We focused on 2 events: the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) approval of China as a trading partner in the purchase and import of ivory stockpiles from Africa in July 2008 and the Chinese government's announcement of a domestic ivory ban in December 2016. Using latent Dirichlet allocation topic modeling, we identified 8 topics about elephant ivory and grouped them into 3 frames: ivory arts and culture, ivory crimes, and elephant conservation. Over the last 2 decades, topics related to ivory crimes remained the most prevalent in news articles. Topics about ivory arts and culture showed a significant shift in media salience before and after the 2 events (from 0.44 to 0.19 and from 0.08 to 0.15, respectively, p < 0.05), whereas the other 2 frames did not change significantly. Contrary to popular belief, our results indicated that Chinese macro-level public opinion on ivory had become more negative following the CITES approval of ivory importation and less negative after the ivory ban announcement, at least for certain periods. The relationship between mass media, public opinion, and wildlife trade policies is complex and requires further examination of the sociopolitical dynamics that influence media narratives. Our results showed the value of topic modeling in monitoring and assessing media representations of wildlife issues in the era of big data. Conservationists should remain vigilant of mass media coverage and collaborate with media practitioners to produce comprehensive narratives on wildlife issues if resources permit.     

New insights into the formation of ammonium nitrate from a physical and chemical level perspective

● Factor analysis of ammonium nitrate formation based on thermodynamic theory. ● Aerosol liquid water content has important role on the ammonium nitrate formation. ● Contribution of coal combustion and vehicle exhaust is significant in haze periods. High levels of fine particulate matter (PM_2.5) is linked to poor air quality and premature deaths, so haze pollution deserves the attention of the world. As abundant inorganic components in PM_2.5, ammonium nitrate (NH₄NO₃) formation includes two processes, the diffusion process (molecule of ammonia and nitric acid move from gas phase to liquid phase) and the ionization process (subsequent dissociation to form ions). In this study, we discuss the impact of meteorological factors, emission sources, and gaseous precursors on NH₄NO₃ formation based on thermodynamic theory, and identify the dominant factors during clean periods and haze periods. Results show that aerosol liquid water content has a more significant effect on ammonium nitrate formation regardless of the severity of pollution. The dust source is dominant emission source in clean periods; while a combination of coal combustion and vehicle exhaust sources is more important in haze periods. And the control of ammonia emission is more effective in reducing the formation of ammonium nitrate. The findings of this work inform the design of effective strategies to control particulate matter pollution.     

酸洗废酸液的热化学再生技术评价

介绍了Lurgi流化床工艺、Ruthner喷雾焙烧工艺、Pori工艺和Pyromars工艺4种酸洗废酸液的热化学再生工艺,从能耗水平、副产物、再生酸纯净度以及环境影响方面对其进行了评价,并总结了该工艺技术领域的改进与创新。指出:基于Pori工艺改进的热水解工艺在能耗方面表现出较大的优势,但其稳定性、可靠性还有待于进一步的实践检验;而对于以燃烧方式供热的Lurgi或Ruthner工艺,更加节能减排的富氧或纯氧燃烧技术是可以尝试的方向。     

沉积物中双酚类化合物的测定

通过前处理与检测条件的全面优化,建立了一种同时实现环境沉积物中9种痕量双酚类化合物的加速溶剂萃取(ASE)-固相萃取(SPE)-高效液相色谱/三重四极杆质谱(HPLC/MSMS)检测方法。沉积物样品先采用甲醇作为溶剂,在70℃条件下进行加速溶剂萃取,萃取液约100 mL,加入甲酸调节pH约为2.5,再经Oasis型HLB固相萃取柱富集与净化,该过程可将沉积物的基质效应控制在85%～95%之间。9种目标化合物在0.05～25.0μg/L(以双酚AF计)范围内呈良好的线性关系,相关系数r>0.999,检出限为0.01～0.25μg/kg,加标回收率为62%～122%,相对标准偏差为0.9%～12.7%。     

西渡造纸厂综合污水处理工程的设计

西渡造纸厂综合工业废水 1 80 0 0m3 /d ,废水中含有纤维、木质素、半纤维素、草屑、泥灰、炉灰和纸浆短纤维等固溶物和微量的可溶性有机物以及碱等 ,同时含有大量的不溶性有机物 ;水呈黑色 ,属难生化的高浓度有机废水。在污水处理工程设计中通过对造纸黑液采用水解酸化 UBF 混凝沉淀联合处理工艺 ,出水可达到《造纸工业水污染物排放标准》(GWPB2 1 999)要求     

内循环颗粒污泥床硝化反应器流体力学特征研究

对内循环颗粒污泥床硝化反应器中的气含率和液体运动速率进行了试验研究 ,建立了分别基于流体力学平衡原理及反应器能量输入与消耗平衡方程的气含率和液体运动速率的机理性数学模型 .根据试验数据 ,在相对误差分别为 4 78%和6 5 3%的情况下对上述模型进行了参数估计 .在实际运行中 ,通过所建模型对反应器中的气含率和液体运动速率进行有效调控 ,可实现反应器的高效稳定运行.