AFM液池成像技术用于微絮体形态结构特性研究

利用原子力显微镜液池成像技术对不同微絮凝时间条件下不同铝形态分布的PACl与SiO2颗粒物所形成絮体的微观形貌结构特性进行了观测与表征,并通过光子相关光谱对絮体生长过程进行激光粒度分析,结合微絮凝过滤工艺进行试验验证。结果表明,新改进的液池成像技术能够较好地反映混凝过程中微絮体的形貌变化特征及不同的絮凝作用机理,从而实现对环境微观界面过程的原位观测与表征。     

Synergistic effect of the sequential use of UV irradiation and chlorine to disinfect reclaimed water

The effectiveness of UV and chlorination, used individually and sequentially, was investigated in killing pathogenic microorganisms and inhibiting the formation of disinfection by-products in two different municipal wastewaters for the source water of reclaimed water, which were from a microfilter (W1) and membrane bioreactor (W2) respectively. Heterotrophic plate count (HPC), total bacteria count (TBC), and total coliform (TC) were selected to evaluate the efficiency of different disinfection processes. UV inactivation of the three bacteria followed first-order kinetics in W1 wastewater, but in W2 wastewater, the UV dose-response curve trailed beyond approximately 10 mJ/cm² UV. The higher number of particles in the W2 might have protected the bacteria against UV damage, as UV light alone was not effective in killing HPC in W2 wastewater with higher turbidity. However, chlorine was more effective in W2 than in W1 for the three bacteria inactivation owing to the greater formation of inorganic and organic chloramines in W1 wastewater. Complete inactivation of HPC in W1 wastewater required a chlorine dose higher than 5.5 mg/L, whereas 4.5 mg/L chlorine gave the equivalent result in W2 wastewater. In contrast, sequential UV and chlorine treatment produced a synergistic effect in both wastewater systems and was the most effective option for complete removal of all three bacteria. UV disinfection lowered the required chlorine dose in W1, but not in W2, because of the higher chlorine consumption in W2 wastewater. However, UV irradiation decreased total trihalomethane formation during chlorination in both wastewaters.     

Morphological and physicochemical characteristics of iron corrosion scales formed under different water source histories in a drinking water distribution system

The corrosion scales on iron pipes could have great impact on the water quality in drinking water distribution systems (DWDS). Unstable and less protective corrosion scale is one of the main factors causing “discolored water” issues when quality of water entering into distribution system changed significantly. The morphological and physicochemical characteristics of corrosion scales formed under different source water histories in duration of about two decades were systematically investigated in this work. Thick corrosion scales or densely distributed corrosion tubercles were mostly found in pipes transporting surface water, but thin corrosion scales and hollow tubercles were mostly discovered in pipes transporting groundwater. Magnetite and goethite were main constituents of iron corrosion products, but the mass ratio of magnetite/goethite (M/G) was significantly different depending on the corrosion scale structure and water source conditions. Thick corrosion scales and hard shell of tubercles had much higher M/G ratio (>1.0), while the thin corrosion scales had no magnetite detected or with much lower M/G ratio. The M/G ratio could be used to identify the characteristics and evaluate the performances of corrosion scales formed under different water conditions. Compared with the pipes transporting ground water, the pipes transporting surface water were more seriously corroded and could be in a relatively more active corrosion status all the time, which was implicated by relatively higher siderite, green rust and total iron contents in their corrosion scales. Higher content of unstable ferric components such as γ-FeOOH, β-FeOOH and amorphous iron oxide existed in corrosion scales of pipes receiving groundwater which was less corroded. Corrosion scales on groundwater pipes with low magnetite content had higher surface area and thus possibly higher sorption capacity. The primary trace inorganic elements in corrosion products were Br and heavy metals. Corrosion products obtained from pipes transporting groundwater had higher levels of Br, Ti, Ba, Cu, Sr, V, Cr, La, Pb and As.     

Improvement of metal adsorption onto chitosan/Sargassum sp. composite sorbent by an innovative ion-imprint technology

Technology for immobilization of biomass has attracted a great interest due to the high sorption capacity of biomass for sequestration of toxic metals from industrial effluents. However, the currently practiced immobilization methods normally reduce the metal sorption capacities. In this study, an innovative ion-imprint technology was developed to overcome the drawback. Copper ion was first imprinted onto the functional groups of chitosan that formed a pellet-typed sorbent through the granulation with Sargassum sp.; the imprinted copper ion was chemically detached from the sorbent, leading to the formation of a novel copper ion-imprinted chitosan/Sargassum sp. (CICS) composite adsorbent. The copper sorption on CICS was found to be highly pH-dependent and the maximum uptake capacity was achieved at pH 4.7-5.5. The adsorption isotherm study showed the maximum sorption capacity of CICS of 1.08 mmol/g, much higher than the non-imprinted chitosan/Sargassum sp. sorbent (NICS) (0.49 mmol/g). The used sorbent was reusable after being regenerated through desorption. The FTIR and XPS studies revealed that the greater sorption of heavy metal was attributed to the large number of primary amine groups available on the surfaces of the ion-imprinted chitosan and the abundant carboxyl groups on Sargassum sp. Finally, an intraparticle surface diffusion controlled model well described the sorption history of the sorbents.     

顶空固相微萃取法用于测定水中二甲基三硫醚

采用顶空固相微萃取一气相色谱/质谱联用的方法对水中嗅味物质二甲基三硫醚进行了测定.经优化试验,得到了二甲基三硫醚固相微萃取的最佳条件:采用CAR/PDMS(85 μm)纤维头、在水样中加入25%(W/V)的NaCl、65℃水浴下顶空萃取30 min.该方法的检出限为5 ng/L,相对标准偏差为2.2%～7.1%,加标回收率为71.5%～87.3%.利用该方法对不同实际水样的检测发现,不同水源水中均有一定程度的二甲基三硫醚检出(9～40 ng/L),值得关注.     

水质在线安全生物预警系统模拟预警及应用

水质安全在线生物预警系统可以实现水体突发性污染事故安全预警,根据受试生物生物学指标变化对水体内多种污染物的综合毒性进行监测。模拟预警结果表明,水质安全在线生物预警技术通过低压电信号采集日本青鳉的行为变化,并通过信号分析系统,结合行为变化阈值的设定,对水质状况进行综合分析,实现对污染水体的水质变化报警。     

Co-variations of bacterial composition and catabolic genes related to PAH degradation in a produced water treatment system consisting of successive anoxic and aerobic units

This paper reports on the investigation of concentration levels of PAHs, community structure, as well as the abundance of PAH-related catabolic genes including upper-pathway dioxygenase genes (nahAc and phnAc) and down-pathway catechol dioxygenase genes (C12O and C23O) in a successive anoxic and aerobic treatment of produced water from the Jidong Oilfield, China. 93% of total PAHs were removed, almost equally contributed by the anoxic and aerobic units. However, PAHs of more than 3 benzene rings remained almost unchanged. The signals for phnAc and C12O were undetectable in this biological system, whereas the existence of nahAc and C23O was confirmed in the system and the copies of the two genes in the aerobic tank were 2 or 3 orders higher than those in the influent water sample. The different behavior of C23O demonstrated that mineralization of PAHs might mainly occur in the aerobic unit. The existence of nahAc and C23O genes in the influent and the high similarity of genotype between the influent and the two sludge samples suggested that bacteria existing in the influent contributed to PAH removal and bacteria harboring PAH catabolic genes were enriched in the sludge.     

石臼漾水源生态湿地工程的水质改善效果

嘉兴市石臼漾水源生态湿地工程是我国目前最大的城市饮用水源处理系统,成为我国微污染水源水质改善的成功范例,已稳定运行4年。对该湿地近3年的水质改善效果研究表明,经过湿地净化,饮用水源水的DO、TP、NH3-N、粪大肠菌群等主要指标提高了一个等级,湿地的主体功能区即根孔生态净化区和深度净化区发挥着相辅相成的净化作用;湿地水质净化效果的季节性变化明显,通常夏、秋暖季的净化效果较好,而冬、春冷季的效果较差;湿地运行3年期间对氨氮的去除效果和DO浓度的增长呈逐年上升趋势,而对浊度、Fe、Mn和TN的去除效果则逐年下降。另外,分析了湿地目前存在的主要问题并提出了相应的对策建议。     

An efficient electron transfer at the Fe/iron oxide interface for the photoassisted degradation of pollutants with H2O2

Fe-200 was synthesized through the calcination of iron powder at 200 °C for 30 min in air. On the basis of characterization by X-ray diffraction and X-ray photoelectron spectroscopy, Fe-200 had a core–shell structure, in which the surface layer was mainly composed of Fe₂O₃ with some FeOOH and FeO, and the core retained metallic iron. The kinetics and mechanism of the interfacial electron transfer on Fe-200 were investigated in detail for the photoassisted degradation of organic pollutants with H₂O₂. Under deoxygenated conditions in the dark, the generation of hydroxyl radicals in aqueous Fe-200 dispersion verified that galvanic cells existed at the interface of Fe⁰/iron oxide, indicating the electron transfer from Fe⁰ to Fe³⁺. Furthermore, the effects of hydrogen peroxide and different organic pollutants on the interfacial electron transfer were examined by the change rate of the Fe³⁺ concentration in the solution. The results indicated that hydrogen peroxide provided a driving force in the electron transfer from Fe²⁺ to Fe³⁺, while the degradation of organic pollutants increased the electron transfer at the interface of Fe⁰/iron oxide due to their reaction with OH.