Fouling of nanofiltration membrane by e uent organic matter: Characterization using di erent organic fractions in wastewater

The UF membrane with molecular weight cuto (MWCO) ranging from 2 to 100 kDa and XAD-8 resin were employed to identify the characteristic of molecular weight (MW) distribution of wastewater e uent organic matter (EfOM) in terms of TOC and UV254, as well as the amounts of the hydrophilic/hydrophobic organic fractions in di erent MW ranges. Then, the nanofiltration (NF) membrane fouling experiments were carried out using the above fractionated water to investigate the e ect of MW distribution and hydrophilic/hydrophobic characteristics of EfOM on the membrane flux decline using the fractionated water samples. The experimental results have shown that 45.61% of the total organics belongs to the low MW one, among which the percentage of the hydrophilic organics with low MW (less than 2 kDa) was up to 28.07%, while that of the hydrophobic organics was 17.54%. In particular, the hydrophilic fraction was found to be the most abundant fraction in the e uents. MW distribution has a significant e ect on the membrane fouling. When the MWwas less than 30 kDa, the lower the MW, the larger was the specific flux decline, while in the case of MW higher than 30 kDa, the higher the MW, the larger was the specific flux decline, and the decline degree of low MW organics was larger than the high MW one. With the same MW distribution range, specific flux decline of the hydrophilic organic was considerably slower than that of the hydrophobic organic, which indicated that the hydrophobic organic fractions dominantly contribute to the flux decline.     

微污染水源中溶解性有机氮组成规律及其水处理特性

以上海市黄浦江和青草沙长江原水为对象,研究了两大水源水中溶解性有机氮(DON)的含量变化、分子组成特征及其在常规净水工艺中的去除效果,并对DON与常规水处理指标间的相关性进行了分析.结果表明:两种原水以DOC、DON和UV254表征的有机物含量均以小分子量(<5kDa)和亲水性有机物为主;微污染黄浦江原水中同时存在外源性及内源性污染,而青草沙长江原水中内源性污染占主导地位;饮用水常规净水处理工艺对黄浦江原水中DON的去除率为40%,优于长江原水DON的去除率16.7%;黄浦江和长江原水DON浓度与DOC和UV254相关性良好,其相关系数分别为0.59,0.52和0.74,0.51;鉴于常规处理对DON去除效果有限,而DON是导致强三致特性含氮消毒副产物(N-DBPs)的总前体物,因此水厂应通过强化常规、深度处理等手段改善DON在净水工艺中的去除效果.     

Description of adsorption of hydrophobic organic compounds on sediment using multi-component adsorption model

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基于QSAR关系预测PCBs和部分PAHs在LDPE中的扩散系数

分子扩散系数（D）是获得污染物与环境介质之间的平衡分配系数（K）的重要前提,然而通过实验测定获取污染物的扩散系数的过程过于繁琐,因此需开发一种更为简单、高效、准确的预测模型来定量预测扩散系数.为此,本文搜集了一些多环芳香烃（PAHs）和多氯联苯（PCBs）在低密度聚乙烯膜（LDPE）上扩散系数（log D）的实测值,基于定量结构-活性关系（QSAR）,利用逐步多元线性回归（MLR）构建了预测D值的模型.模型的决定系数R_adj²为0.941,交叉验证系数Q_LOO²为0.934,外部系数Q_ext²为0.895.结果表明,该QSAR模型具有良好的拟合优度、稳健性和预测能力,其可用来预测应用域内有机污染物在LDPE膜上的扩散系数.     

生物炭吸附雨水径流难生物降解有机氮效能及机制

有机氮（ON）在雨水径流氮素污染中起关键作用,但多数研究只关注可生物降解有机氮的生物转化去除,忽略了占比较高的难生物降解有机氮.以生物炭作为吸附剂,探究其对雨水径流典型难生物降解有机氮（吲哚）的吸附效能及机制.结果表明,原始生物炭对吲哚有较高的单位吸附量（45 mg·g^-1）,生物炭投加浓度为0.4 g·L^-1时其表面平均吸附位点利用度最高.H₂O₂和NaOH改性生物炭对吲哚的吸附量是原始生物炭的1.3倍和1.6倍,吸附机制包括疏水相互作用、氢键和π-π电子供体-受体（π-π EDA）作用,以疏水相互作用为主,其中H₂O₂改性通过增加生物炭表面含氧官能团来加强氢键和π-π EDA作用,而NaOH改性生物炭通过大幅提高生物炭比表面积来加强疏水相互作用,故NaOH改性吸附效果更优.综上,生物炭对难生物降解有机氮具有较强去除作用,通过NaOH改性还能大幅提高效率,故在雨水径流氮素污染较高的地区把NaOH改性生物炭作为生物滞留池中的填料有着极大的应用潜力.     

风力机叶片防除冰技术研究现状

提出了风力机防除冰的关键部件是叶片,并介绍了风力机叶片覆冰的影响,叶片防冰的主动与被动型方法及其各自的优缺点。重点阐述了憎水涂料防冰法的研究现状,并总结了憎水性涂料防冰的三大主要效果。对目前风力机叶片防除冰技术的主流方法进行了综合评价,并指出了其日后的发展方向。     

改性聚氨酯海绵的合成及其油水分离性能

以膨胀石墨与氧化锌为原料,采用复合改性法改性聚氨酯海绵,在硅烷偶联剂的作用下,用月桂酸的醇溶液表面修饰后制备出改性聚氨酯海绵. 通过扫描电子显微镜(SEM)与接触角测定仪进行表征,对改性聚氨酯海绵的吸油、吸水及循环使用性能进行了测定,并试验获得了最佳的油水分离条件. 结果表明:改性聚氨酯海绵具有良好的疏水超亲油性,在膨胀石墨分散液与氧化锌胶体溶液体积比为1∶1时,对于质量浓度为20 g/L的机油水溶液,饱和单位吸油量最高可达17.7 g/g,对机油的选择性吸附系数为10.41,油水分离效果最佳;在选择吸附过程中,15 min以内油水分离效率就能达到78.41%;改性聚氨酯海绵每次循环利用后,单位吸油量的减幅均低于7.3%,循环使用性能良好. 研究显示,该种改性聚氨酯海绵对油水体系中的油类具有很好的选择性,吸附完成后,经过简单的挤压将油回收后即可循环利用,具有便捷、高效、循环、无二次污染的特性.      

白云母/硅微粉疏水改性对三相泡沫热稳定性的影响

为了制备高热稳定性的三相泡沫,对白云母/硅微粉疏水改性。采用十六烷基三甲氧基硅烷(HTEOS)为改性剂,以接触角、粒度分析、FTIR为表征。在合成蛋白泡沫中按比例添加粉体制备三相泡沫,以自主设计可视化油池进行热稳定性试验并与两相泡沫对比。结果表明:改性白云母的性质为“两亲”,改性硅微粉表现为疏水;三相泡沫热稳定性高于两相泡沫,三相泡沫中,利用改性白云母制备的三相泡沫热稳定性最优,覆盖至破灭时间为1 905 s,而改性硅微粉制备的三相泡沫热稳定性不足,覆盖至破灭时间仅为983 s。     

Performance tests of newly developed adsorption/plasma combined system for decomposition of volatile organic compounds under continuous flow condition

The adsorption/plasma decomposition with the combination of adsorption honeycomb-sheets and a plasma element is a new technology for small-sized apparatuses to decompose volatile organic compounds (VOCs) at concentrations lower than about 100 ppm. The feasibility of the prototype adsorption/plasma decomposition apparatus was evaluated with the simulated exhausts containing one VOC component and with real exhausts from a painting booth and an adhesion factory. The apparatus decomposed VOCs e ectively at the painting booth exhaust but not always satisfactorily at the adhesion factory exhaust. The performance test results with real exhausts were discussed with respect to the concentration and discharge pattern of the exhausts and the basic properties of the system such as cooperation of adsorption and plasma reaction and the concentration dependence of the performance.     

混合有机污染物在土壤中的竞争吸附研究

采用3种不同的溶质加入法研究溶质的吸附平衡,即方案①:先加入萘,然后再加入菲;方案②:萘和菲同时加入;方案③:先加入菲,然后再加入萘.研究结果表明同一溶质在有其它溶质竞争的情况下,表现出与单一纯溶质吸附时不同的吸附行为.随着竞争溶质浓度的增加,萘的吸附等温线的线性程度不断升高,吸附量降低.而菲则只是在实验方案③时,线性程度明显升高.随着竞争溶质初始浓度的增加,K_OC的值不断减小,当竞争浓度大约增加到0.5S_w后,K_OC基本不变化,达到了最小值.同时发现分子体积较大、厌水性较强的菲比分子体积较小、厌水性较弱的萘具有更强的竞争吸附能力.