Impact of pre-oxidation on the formation of byproducts in algae-laden water disinfection: Insights from fluorescent and molecular weight

Pre-oxidation has been reported to be an effective way to remove algal cells in water, but the released algal organic matter (AOM) could be oxidized and lead to the increment in disinfection by-product (DBP) formation. The relationship between pre-oxidation and AOM-derived DBP formation needs to be approached more precisely. This study compared the impact of four pre-oxidants, ozone (O₃), chlorine dioxide (ClO₂), potassium permanganate (KMnO₄) and sodium hypochlorite (NaClO), on the formation of nitrogenous (N-) and carbonaceous (C-) DBPs in AOM chlorination. The characterization (fluorescent properties, molecular weight distribution and amino acids concentration) on AOM samples showed that the characterization properties variations after pre-oxidation were highly dependent on the oxidizing ability of oxidants. The disinfection experiments showed that O₃ increased DBP formation most significantly, which was consistent with the result of characterization properties variations. Then canonical correspondent analysis (CCA) and Pearson's correlation analysis were conducted based on the characterization data and DBP formation. CCA indicated that C-DBPs formation was highly dependent on fluorescent data. The formation of haloacetic acids (HAAs) had a positive correlation with aromatic protein-like component while trichloromethane (TCM) had a positive correlation with fulvic acid-like component. Pearson's correlation analysis showed that low molecular weight fractions were favorable to form N-DBPs. Therefore, characterization data could provide the advantages in the control of DBP formation, which further revealed that KMnO₄ and ClO₂ were better options for removing algal cells as well as limiting DBP formation.     

CASS工艺在医院污水处理中的应用效果研究

通过采样分析以及考察CASS工艺在徐州某医院污水处理中的实际应用效果情况.结果发现,进水CODG、BOD5、氨氮、TP和总大肠茵群,质量浓度分别为200～300,120～260,7～15,26～3.5 mg/L和大于24000个/L,对应地,出水质量浓度分别为23～65,11～65,0.1～2.8,1.2～1.6 mg/L和小于1000个/L.去除率分别为77.38%～37%,41.73%～54.54%,73.57%～92.78%,66.36%～90.91%和97.08%～99.83%.检测的各项指标除TP外均达到了<污水综合排放标准>中的二级排放标准.针对TP超标问题,并且从CASS工艺除磷的原理及各影响因素方面分析了其超标原因,可能是由于回流污泥中携带的硝酸盐抑制了磷的有效释放.建议利用反硝化除磷原理.将厌氧区设计成1个相对独立的区域,以达到更好的除磷效果,以便为CASS工艺在提出更高的水质要求条件下,依旧能够发挥其作用.     

生态调控后贵州花溪水库浮游植物群落结构的变化特征及影响因素

为了解生态调控后花溪水库浮游植物功能群变化特征与环境因子的关系,基于浮游植物功能群、NMDS(非度量多维尺度分析)、RDA(冗余分析)、Pearson相关性分析方法,于2017年3月—2018年3月逐月对浮游植物群落结构与水环境指标进行采样分析.结果表明:①生态调控前,花溪水库共鉴定浮游植物4门18种,共归类出10个功能群,且功能群H1占绝对优势,其代表藻种为水华束丝藻(Aphanizomenon flosaquae);生态调控后,共鉴定浮游植物6门66种,共归类出20个功能群,主要优势功能群为B/Lo,其代表藻种为小环藻(Cyclotella sp.)和多甲藻(Peridinium sp.).②生态调控后,花溪水库优势功能群结构发生了变化,其变化特征为B/Lo(春季)→D/B/Lo/X2/N/P(夏季)→D/B/Lo/N(秋季)→D/MP/B/Lo/W1/W2(冬季).功能群B的生物量在春季达到峰值(3 056.3μg/L),与其对低营养环境有良好的耐受性有关;功能群Lo的生物量在秋季达到峰值(2 900.9μg/L),与组成功能群Lo的甲藻特性有关.③RDA结果表明,生态调控前影响...     

咪唑型离子液体对小鼠的急性毒性

采用寇氏改良法研究了咪唑型离子液体对小鼠的急性毒性,并考察了烷基侧链长度对其毒性的影响,同时采用HE染色法观察了其对小鼠肝脏的毒性.结果表明,4种咪唑型离子液体([C10mim]Br、[C12mim]Br、[C14mim]Br和[C18mim]Br)对小鼠肝脏均有损伤,其LD50值在98.91～220.16 mg·kg...     

混凝土空心楼盖板柱增强节点抗震性能试验研究∗

为研究空心楼盖板柱增强节点的抗震性能,进行了3个板柱节点在低周往复荷载作用下的拟静力试验,对节点的承载能力、开裂模式、破坏形态、滞回曲线、位移延性、刚度退化和耗能能力等进行了较为系统的研究。结果表明：平行布管方式下空心板柱节点的承载力、刚度、耗能能力和刚度退化等抗震性能指标均优于正交布管方式布管下的板柱节点;配置型钢剪力架能显著提高空心楼盖板柱节点承载力与抗震性能,配置弯起钢筋对节点抗震性能提高的作用不明显。建议工程应用时综合考虑空心楼盖板柱节点的抗冲切与抗震需求来选择增强元件,同时根据建筑平面布局和抗侧力结构布置等情况,合理选择空心芯管的布置方向,以提高结构整体抗震性能。研究成果可为采用空心管（或柱状芯材）的空心楼盖板柱结构的研究和应用提供参考。     

基于落石棚洞冲击试验的落石冲击力研究

基于落石棚洞冲击试验,考虑不同落石重量、高度和冲击角度对落石冲击力的影响,分析了落石冲击力在这三个因素影响下的变化规律,发现落石高度与棚洞顶板倾角共同变化时,随着落石高度的增加和棚洞顶板倾角的减小落石冲击力增大,增大幅度达80.02%;落石高度与重量共同变化时,当落石重量较小,落石冲击力随着落石高度增加后的变化幅度较小,反之较大,最大值较最小值的增大幅度达182.10%;棚洞顶板倾角和落石重量共同变化时,落石重量比棚洞顶板倾角对落石冲击力的影响大,增大幅度达48.99%。然后基于正交试验分析发现落石重量是影响落石冲击力最重要的因素,其次为落石高度,最后为棚洞顶板倾角。最后通过回归分析获得了棚洞落石冲击力计算公式,并通过方差分析证明了棚洞落石冲击力计算公式与各因素间的回归关系高度显著,因此该公式可用于落石棚洞设计时冲击力的计算。     

以羟胺为底物的自养脱氮微量热研究

羟胺（NH₂OH）是单级自养脱氮系统物质转化的重要中间产物。从稳定运行（氨氮去除率维持90%以上,总氮去除率维持在80%以上）的单级自养脱氮工艺（SBBR）取活性污泥放入量热池,加入不同浓度N-NH₂OH（40～200 mg/L）进行量热实验研究。结果表明,用Boltzmann模型可以很好地表达量热值与NH₂OH浓度的关系,超过一定浓度的羟胺会抑制微生物活性,自营养脱氮过程的产热增量降低。     

Influencing factors and prediction of ambient Peroxyacetyl nitrate concentration in Beijing, China

Peroxyacyl nitrates (PANs) are important secondary pollutants in ground-level atmosphere. Accurate prediction of atmospheric pollutant concentrations is crucial to guide effective precautions for before and during specific pollution events. In this study, four models based on the back-propagation (BP) artificial neural network (ANN) and multiple linear regression (MLR) methods were used to predict the hourly average PAN concentrations at Peking University, Beijing, in 2014. The model inputs were atmospheric pollutant data and meteorological parameters. Model 3 using a BP-ANN based on the original variables achieved the best prediction results among the four models, with a correlation coefficient (R) of 0.7089, mean bias error of ? 0.0043 ppb, mean absolute error of 0.4836?ppb, root mean squared error of 0.5320?ppb, and Willmott's index of agreement of 0.8214. Based on a comparison of the performance indices of the MLR and BP-ANN models, we concluded that the BP-ANN model was able to capture the highly non-linear relationships between PAN concentration and the conventional atmospheric pollutant and meteorological parameters, providing more accurate results than the traditional MLR models did, with a markedly higher goodness of R. The selected meteorological and atmospheric pollutant parameters described a sufficient amount of PAN variation, and thus provided satisfactory prediction results. More specifically, the BP-ANN model performed very well for capturing the variation pattern when PAN concentrations were low. The findings of this study address some of the existing knowledge gaps in this research field and provide a theoretical basis for future regional air pollution control.     

长江流域太湖区降雨侵蚀力及其应用的研究

本研究利用太湖区代表站３０年和４３个一般站２５年的降雨资料，改进和完善了降雨侵蚀力新算法，使之与经典法达到９０％的一致性，查清了该区降雨侵蚀力时空变化持证，并编制出全区阵雨侵蚀力（Ｒ）值分布图。同时，还时Ｒ值在水土保持、耕作制度变革和防洪减灾中的应用，尤其对１９９１年特大洪涝灾害的根本原因，作了讨论。太湖区Ｒ值较大，不可忽视水土保持，做好山区、坡耕地的水土保持，是防洪减灾最长久有效的根本措施。