Potential of ozonation for the degradation of antibiotics in wastewater.

Increasing concern in recent years over the occurrence and fate of low-level concentrations of pharmaceuticals in the aquatic environment stimulates research on alternative treatment methods. This paper presents a study of the degradation of sulphamethoxazole, an antibiotic used on humans and animals in order to treat various bacterial infections, by ozonation. After 4.5 min of treatment, the concentration of sulphamethoxazole was below the HPLC detection limit of 0.6 mgL(-1), indicating degradation efficiency higher than 99.24%. This value is comparable and in some cases higher than published data on the degradation in drinking water. Kinetic analysis of the data indicated an overall first-order reaction with a rate constant of 1.0594 min(-1) at 20 degrees C. The reaction order differs with the second-order reaction observed by other researchers. This change of reaction order could be explained by the different treatment conditions used. Preliminary analysis using the FT-IR technique was also performed in order to obtain information on the structure of the degradation products. Further analysis using a GC-MS is needed in order to elucidate the structure of the degradation products. Finally, based on the experiments performed, ozonation seems to be a promising technique for the degradation of antibiotics, even in wastewater.     

Simultaneous photocatalytic oxidation of pharmaceuticals and inactivation of Escherichia coli in wastewater treatment plant effluents with suspended and immobilised TiO(2)

Simultaneous Escherichia coli inactivation and oxidation of pharmaceuticals in simulated wastewater treatment plant effluents has been investigated using a photocatalytic treatment with TiO(2) in suspension and immobilised onto a fixed-bed reactor. Non-photocatalytic reference experiments of dark adsorption and photolysis showed a higher sensitivity of E. coli towards the chemical composition of water in comparison with the concentration of pharmaceuticals that remains unaffected. Moreover, it must be underlined that the presence of pharmaceuticals (including antibiotics) did not seem to affect the bacterial viability at such low concentrations. Concerning photocatalytic experiments, both suspended and immobilised TiO(2) were able to simultaneously inactivate and oxidise both kinds of pollutants (bacteria and pharmaceuticals). The fixed-bed reactor showed similar activity to that of the slurry without deactivation after several cycles of reuse. That makes TiO(2) photocatalysis a quite interesting technology for the treatment of drinking water supplies or wastewater plant effluents, allowing the removal of emerging contaminants such as pharmaceuticals during the disinfection treatment.     

不同卸荷损伤程度砂岩吸水特性试验研究

针对边坡岩体开挖卸荷后遇水极易失稳的现象,以三峡库区典型砂岩为研究对象,通过三轴加卸荷试验确定岩样不同卸荷损伤程度,然后进行自由吸水试验,研究不同卸荷损伤程度砂岩的吸水特性变化规律。试验结果表明：① 岩样吸水后表面水位高度的变化具有明显的时间效应。吸水初期,水位高度增加速度较快,之后逐渐减小。② 岩样吸水稳定后,水位高度随卸荷量的增加而增加。当卸荷量较大,卸荷损伤岩样有裂缝产生时,吸水速度明显增加,且水位高度沿着裂缝均匀分布。③ 同一围压下的岩样,吸水率随着卸荷量的增加而增加,其增加速度也随着卸荷量的增加逐渐加快。这是由于随着卸荷量的增加,岩样内部裂纹逐渐扩展,当卸荷量继续增加至岩样内部裂纹贯通后,吸水率就随之急剧增加。当裂纹最终贯通以后,岩样的吸水率与围压之间的关系不再显著。④ 当卸荷量为一定值时,随着围压的增加,卸荷损伤岩样吸水率逐渐增加。但是当卸荷量较大时,岩样吸水率随着围压的增加先增大后减小,但变化幅度较小。上述成果可为开挖卸荷边坡支护时机及方案的选择提供一定的借鉴。     

Sorption of polycyclic aromatic hydrocarbons into liposomes (artificial cell membranes) and the effects of dissolved natural organic matter

Dissolved natural organic matter (NOM) occurs widely in the aquatic environment and affects the fate of microorganic pollutants (e.g. intake, accumulation, movement, degradation, toxicity). The effect of NOM on the intake into biota (living cells) is very important. In the present study, the effects of coexisting NOM on the intake of microorganic pollutants into aquatic biota were experimentally evaluated. The NOM was concentrated from Lake Biwa water using a reverse osmosis filtration membrane. Two polycyclic aromatic hydrocarbons (PAH; pyrene and phenanthrene) were used as representative microorganic pollutants. Liposomes were synthesized in the laboratory to simulate living cell membranes and were used to investigate the intake of microorganic pollutants into aquatic biota. The experimental results (PAH onto NOM, NOM into liposomes, and PAH into liposomes) indicated that the sorption of PAH into liposomes was suppressed, apparently by PAH binding with NOM in the aqueous phase. This suggests that the accumulation and/or toxicity of microorganic pollutants can be retarded by NOM in the aqueous environment. Moreover, the experimental results indicated that sorption into liposomes (the liposome/water sorption coefficient, K_lipw) could be a better parameter for estimating the intake of microorganic pollutants into aquatic biota than the n-octanol/water partition coefficient (K_ow) in the aqueous environment.     

湿热环境对BFRP筋拉伸性能的影响

在海洋工程中,海水中Cl-、SO42-和Mg2+会侵蚀进入钢筋混凝土内部,造成混凝土的膨胀破坏,严重影响混凝土结构的耐久性.BFRP筋具有优良的耐腐蚀性能,可以避免钢筋锈蚀带来的耐久性问题,因而在海工混凝土领域具有广阔的应用前景.该文研究了湿热环境下BFRP筋的吸水性能,并探讨了BFRP筋在蒸馏水、碱溶液和海水中浸泡不同龄期的拉伸性能变化规律.试验结果表明:湿热环境下,BFRP筋在蒸馏水和碱溶液中的吸水过程分为两个阶段,浸泡早期BFRP筋的吸水速率快速增加,后期吸水速率减慢.在蒸馏水、碱溶液和海水中浸泡,BFRP筋的拉伸性能随浸泡温度和浸泡龄期的增长而逐步下降,且随着温度的提高,下降幅度较大.在海水浪溅区暴露半年之后,BFRP筋的拉伸性能基本保持不变.     

基于水位-面积-湖容关系的东洞庭湖动态纳污能力分析

为测算不同水文水质条件下东洞庭湖动态纳污能力,利用2003—2016年MODIS遥感数据和实测水文数据建立水位-面积-湖容关系模型,提取不同水位、入湖流量、入湖水质条件下的纳污能力计算参数,参照《水域纳污能力计算规程》测算出不同水文水质条件下的东洞庭湖动态纳污能力系数以及COD、氨氮的动态纳污能力。研究结果表明:东洞庭湖纳污能力随着水位、流量、水质而动态变化,COD最小纳污能力为14 200 g/s,大于2016年年均排放强度1 837 g/s,不存在水质超标风险;氨氮最小纳污能力43 g/s,小于2016年年均排放强度275 g/s,水质超标风险大;明确了导致氨氮超标的水文、水质条件,认为氨氮入湖浓度<0.95 mg/L时,湖泊氨氮不超标。主要结论为:①水位-面积-湖容关系模型可为测算湖泊动态纳污能力提供支撑;②建议根据动态水域纳污能力确定污染物排放量,科学利用水环境容量;③东洞庭湖入湖氨氮浓度应控制在0.95 mg/L以下,以保证水质达标。研究成果对维护和改善洞庭湖水环境质量具有重要的现实意义。     

Presence and risk assessment of pharmaceuticals in surface water and drinking water

Trace amounts of pharmaceuticals have been detected in surface waters in the nano- to microgram per liter range, and in drinking water in the nanogram/L range. The environmental risks of pharmaceuticals in surface waters have been evaluated and generally found to be low if the wastewater is treated before release to the environment. The human health risks of trace amounts of pharmaceuticals in drinking water have however not been evaluated in any great depth. Preliminary screening level assessments suggest risk to be low--but the public and decision-makers are concerned and would like the matter investigated more thoroughly, especially with regards to mixture effects, chronic long-term effects and sensitive sub-populations. The World Health Organization is currently evaluating the need for credible health based guidance associated with low concentrations of pharmaceuticals in drinking water. The aim of this paper is to summarize the state-of-the-science and the ongoing international debate on the topic.     

On the effect of pharmaceuticals on bacterial nitrite oxidation.

Pharmaceuticals or their metabolites are partially excreted with urine or faeces ending up in raw sewage. Many of these substances are not biodegradable and their presence in influents of municipal wastewater treatment plants may cause adverse effects to sensitive biological processes such as nitrification, while on the other hand, they may go through the activated sludge process unreacted. The second step of nitrification, i.e. oxidation of nitrite to nitrate is particularly sensitive. Inhibition of this step under uncontrolled conditions may lead to accumulation of nitrite nitrogen in the plant effluent, a form of nitrogen which is particularly toxic. The effects caused by the presence of seven different pharmaceuticals to a culture of nitrite-oxidizing bacteria isolated from activated sludge are presented. These pharmaceuticals were ofloxacin, propranolol, clofibrate, triclosan, carbamazepine, diclofenac and sulfamethoxazole. Different effects were observed for each of the pharmaceuticals tested in this study. In the cases of ofloxacin and sulfamethoxazole significant inhibition was observed. Triclosan presented a substantial inhibitory effect on the substrate (nitrite) reduction rate. The long-term effect of triclosan on nitrite oxidizers was also examined in a CSTR reactor and conclusions were drawn regarding the reversibility of the inhibition caused by this compound.     

Reducing micropollutants with source control: substance flow analysis of 212 pharmaceuticals in faeces and urine.

Pharmaceuticals in the aquatic environment are raising concern. It is expected that many anthropogenic pharmaceuticals are largely excreted via urine; a popular argument for introducing urine source separation. However, to date, this assumption lacks verification. We close this gap with quantitative screening of official pharmaceutical data. We analysed the excretion pathways of 212 pharmaceuticals' active ingredients (AI), equalling 1,409 products. On average, 64% (+/-27%) of each AI was excreted via urine, and 35% (+/-26%) via faeces. In urine, 42% (+/-28%) of each AI was excreted as metabolites. However, these numbers need cautious interpretation. We found an extreme variability (1) between different therapeutic groups, (2) within some groups and (3) sometimes even between products of the same AI. We discuss various therapeutic groups and include Swiss sales' quantities. For instance, urine source separation could very effectively remove the highly sold and non-degradable x-ray contrast media: 94% (+/-4%) are excreted via urine. However, for different pharmaceuticals belonging to cytostatics, excretion via urine was 6-98%. Because of such large variability we advise caution to introduce the still imperfect urine separation technology solely because of pharmaceuticals. Nonetheless, together with other good arguments for this innovation, removal of pharmaceuticals is a welcome side effect.     

库岸边坡水-岩作用对节理砂岩力学特性影响研究

三峡库区蓄水之后,库水位在145 m和175 m之间呈周期性的升降变化趋势,考虑消落带岩体的实际赋存环境,设计进行了考虑水压力升降变化和浸泡-风干循环的水-岩作用试验,分析了水-岩作用的劣化效应。研究结果表明:(1)节理砂岩抗压强度、变形模量随节理倾角的变化呈先减小再增大的U形变化规律,在周期性水-岩作用下,节理砂岩的抗压强度和变形模量劣化效应明显,其中前5次水-岩作用导致的劣化效应尤为显著;(2)水-岩作用使得节理砂岩的各向异性力学特性逐渐减弱,其中,抗压强度的各向异性度从1.56降低到1.41,变形模量的各向异性度从1.53降低到1.33;(3)水-岩作用不仅使得岩体整体力学性质劣化,也逐渐改变节理岩体的破坏模式,导致不同倾角节理砂岩力学特性劣化趋势存在明显差异,其中,在节理倾角为0°和90°附近时,水-岩作用导致的劣化幅度相对较大,而节理倾角为60。左右时的劣化幅度相对较小。研究结果可为库岸边坡的长期变形稳定分析提供较好的参考。     

Characterization and degradation process of sludge profiles inside a facultative pond (Patagonia, Argentina)

To investigate the characteristics and degradation process in sludge profile, three sampling sessions were made in three different places inside the primary facultative pond of Puerto Madryn city, which was located in a region with a temperate climate in coastal Patagonia (Argentina). The sludge showed an extremely negative redox potential (between -441 and -282 mV) and elevated water content and organic matter concentration, ranging from 83.3 to 97.1% for porosity and from 22.5 to 64.4% for organic matter. The surface layer at the Outlet station during the summer showed the greatest concentration of pigments, reaching a maximum value of 10.6 mg/g for chlorophyll-a and 40.9 mg/g for phaeophytin, and a fast diminution with sediment depth. The important concentration of pigment in the surface layer, coincident with phytoplankton bloom in the water column, could support the importance of nitrogen removal via uptake and organic sedimentation in the water column. In warm months the degradation rate was clear, as reflected in a decrease in sediment layer, and even part of the clay bottom was captured inside an 8 cm core sample, registering extremely low concentrations of pigments, carbohydrates, proteins and lipids. The season and the degree of treatment have an influence on sludge characteristics and the organic matter degradation process.     

Effects of boundary conditions on the cleaning efficiency of riverbank filtration and artificial groundwater recharge systems regarding bulk parameters and trace pollutants

Drinking water is often produced from surface water by riverbank filtration (RBF) or artificial groundwater recharge (AGR). In this study, an AGR system was exemplarily investigated and results were compared with those of RBF systems, in which the effects of redox milieu, temperature and surface water discharge on the cleaning efficiency were evaluated. Besides bulk parameters such as DOC (dissolved organic carbon), organic trace pollutants including iodinated X-ray contrast media, personal care products, complexing agents, and pharmaceuticals were investigated. At all studied sites, levels of TOC (total organic carbon), DOC, AOX (adsorbable organic halides), SAC (spectral absorption coefficient at 254 nm), and turbidity were reduced significantly. DOC removal was stimulated at higher groundwater temperatures during AGR. Several substances were generally easily removable during both AGR and RBF, regardless of the site, season, discharge or redox regime. For some more refractory substances, however, removal efficiency turned out to be significantly influenced by redox conditions.     

Predicting suspended sediment concentration from nephelometric turbidity in organic‐rich waters

Nephelometric turbidity is an optical index for the side scattering of light caused by fine particles suspended in water. When a mixed composition of suspended inorganic and organic materials, including dissolved organic material, is present, turbidity measurements can be affected by the different optical properties of the organic and inorganic materials present, and different turbidimeters are more or less sensitive to these influences. Two different methods of nephelometric turbidity measurement were assessed (using instruments confirming to two different turbidity standard methods: EPA 180.1 and ISO 7027). We investigated the influence of particulate organic matter and coloured dissolved organic matter on relationships between turbidity and suspended sediment concentration for rivers in diverse Otago catchments, in the South Island of New Zealand. The presence of organic matter and dissolved colour affected turbidity measurement owing to light absorption; however, turbidity measurement following the ISO 7027 standard, which specifies near infrared radiation at wavelengths where organic absorption is very weak, was less affected by organics. As a result, rating equations between suspended sediment and turbidity may be significantly different with ISO 7027 compared with EPA 180.1 methods.     

Fate of pharmaceuticals and bacteria in stored urine during precipitation and drying of struvite

Experiments were conducted to measure the behaviour of eight pharmaceuticals during urine treatment as part of the project 'SANIRESCH - Sustainable sanitary recycling Eschborn'. Urine was collected from 200 people in a public building via waterless urinals and NoMix toilets. It was then stored at room temperature at different pH values to analyse the extent to which bacteria and pharmaceuticals are eliminated over time. Although a partial elimination of pharmaceuticals could be detected, the storage at defined pH values cannot be advised. As the persons tested used pharmaceuticals with different structures, in different amounts and at varying intervals, this method of treatment is insufficient for removing them from urine. Precipitating the urine with MgO, washing it with saturated struvite solution and drying it at 30 °C will result in a free-flowing granular powder of struvite (NH(4)MgPO(4)·6H(2)O) that is free of pharmaceuticals and pathogens and can be used as fertiliser and a source of nitrogen, magnesium and phosphorus.     

Effects of surface charge, micro-bubble size and particle size on removal efficiency of electro-flotation.

Flotation is a water treatment alternative to sedimentation, and uses small bubbles to remove low-density particles from potable water and wastewater. The effect of zeta potential, bubble size and particle size on removal efficiency of the electro-flotation process was investigated because previous model-simulations indicated that these attributes are critical for high collision efficiency between micro-bubbles and particles. Solutions containing Al3+ as the metal ion were subjected to various conditions. The zeta potentials of bubbles and particles were similar under identical conditions, and their charges were influenced by metal ion concentration and pH. Maximum removal efficiency was 98 and 12% in the presence and absence of flocculation, respectively. Removal efficiency was higher when particle size was similar to bubble size. These results agree with modelling simulations and indicate that collision efficiency is greater when the zeta potential of one is negative and that of the other is positive and when their sizes are similar.     

干湿循环作用下石膏岩劣化效应的试验研究

选取巴东十字垭隧道的石膏岩为研究对象,室内完成了0,1,3,6,12次干湿循环试验,测得了循环过程中吸水率、孔隙度和单轴压缩的试验数据。试验表明:石膏岩的吸水率和孔隙度与干湿循环次数呈对数函数形式,并随着干湿循环次数的增多而不断增大,但吸水率、孔隙度的增加量却逐渐减少;同样,石膏岩的单轴抗压强度和弹性模量随着干湿循环次数的增多而减小,并随着循环次数的增多,单轴抗压强度和弹性模量的减少量逐渐减少。通过分析对比石膏岩劣化参数变化率,得到干湿循环作用对石膏岩各个参数的劣化效果是不同的,其排序为:吸水率＞弹性模量＞单轴抗压强度＞孔隙度。     

A new methodology for the assessment of large woody debris accumulations on highly modified rivers (example of two French Piedmont rivers)

Methodologies that have been developed to quantify large woody debris (LWD) have been largely tested and adapted for mountain streams of the Pacific Northwest, characterised by a very high density of LWD, composed of large pieces of wood. In French rivers, LWD studies have focused on larger systems presenting low density and discrete distributions of LWD accumulations, where existing methods could not readily be used. We thus propose an easy-to-use method to quantify LWD within such systems. After defining three representative types of LWD, the volume is obtained by representing each LWD accumulation by a simple geometric form in order to measure its height, width and length. A model is then built for the different accumulation types to estimate wood mass from the measured volume. Since the measured volume is a combination of air and wood, we quantified the proportion of air, which is, respectively, equal to 18, 90 and 93% for trunks, wood jams and shrubs. To understand variability in wood mass, we evaluated the influence of different factors on wood density (defined as the ratio between mass and volume). The main factor was found to be the water absorption capacity of the wood, whereas a lesser factor was the degree of wood decay. Most wood pieces were found to increase their mass by an average of 100% and more after only 24 h in contact with water. Moreover, the observed levels of water loss and water absorption during the first 24 h of removal or exposure to water imply major short-term variations in wood mass, which may have significant consequences for wood transport during flooding. © 1998 John Wiley & Sons, Ltd.     

Quantitative study of degradation coefficient of pollutant against the flow velocity

The pollutant degradation coefficient is one of the key parameters to describe the water quality change, for establishing a reasonable water quality model and to determine the water carrying capacity and the environmental capacity. In this research, the environmental channel experiment is conducted to simulate the degradation evolution of the COD and NH3-N under different flow velocity conditions in typical pollution water. It is shown that the processes of the COD and the NH3-N's concentration over time are quite consistent with the first-order kinetic equation and the degradation coefficients increase with the increase of the flow velocity. When the flow velocity varies from 0 m?s-1 to 0.87 m?s-1, the degradation coefficients of the COD and NH3-N increase from 0.011 d-1 to 0.071 d-1 and 0.038 d-1 to 0.258 d-1, respectively. Moreover, the COD and NH3-N's degradation coefficients both have excellent correlation with the reaction time. There is a good linear relationship between the COD degradation coefficient and the flow velocity as well as a good power exponential function between the NH3-N degradation coefficient and the flow velocity. The comparative analysis of the Youth canal prototype monitoring and the calculation results shows that the quantitative formula obtained from the indoor water channel experiments gives results very close to the prototype observation results, which could reflect the degradation of pollutants in river water with varying flow velocity.     

砂岩在化学腐蚀和冻融循环共同作用下力学特征劣化的试验研究

通过冻融循环试验的方法,研究砂岩在不同化学溶液下经冻融循环后的损伤劣化机制和力学特性,分析了砂岩在不同化学溶液中经历不同冻融循环次数后,单轴压缩和三轴压缩下力学性能的变化规律;初步分析了化学腐蚀和冻融循环共同作用对砂岩的损伤劣化机理;同时,定义了损伤变量来定量分析砂岩的损伤劣化程度。试验结果表明:浸泡在0.1 mol/L(H_2SO_4)、0.1 mol/L(NaOH)和p H=7.0蒸馏水中,随着冻融循环次数的增加,砂岩试样的峰值强度和弹性模量均呈指数函数劣化,而其轴向峰值应变却呈指数函数增加。砂岩的损伤程度随着冻融循环次数的增加而逐渐增大;在H_2SO_4溶液中砂岩的损伤劣化程度大于NaOH和pH=7.0蒸馏水;H_2SO_4溶液加剧了砂岩的冻融损伤劣化,而0.1 mol/L(NaOH)溶液对砂岩试样的冻融损伤劣化却有一定的抑制作用。化学腐蚀和冻融循环共同作用下,水化学溶液虽然在一定程度上缓解冻融循环所引起岩石的损伤劣化,但同时岩石遭受着水化学溶液的腐蚀作用;水化学溶液与冻融循环的共同作用对岩石的损伤劣化是相互促进的,共同影响着砂岩的损伤劣化。     

Evaluation of the combined solar TiO2/photo-Fenton process using multivariate analysis.

The effect of combining the photocatalytic processes using TiO2 and the photo-Fenton reaction with Fe3+ or ferrioxalate as a source of Fe2+ was investigated in the degradation of 4-chlorophenol (4CP) and dichloroacetic acid (DCA) using solar irradiation. Multivariate analysis was used to evaluate the role of three variables: iron, H2O2 and TiO2 concentrations. The results show that TiO2 plays a minor role when compared to iron and H2O2 in the solar degradation of 4CP and DCA in the studied conditions. However, its presence can improve TOC removal when H2O2 is totally consumed. Iron and peroxide play major roles, especially when Fe(NO3)3 is used in the degradation of 4CP. No significant synergistic effect was observed by the addition of TiO2 in this process. On the other hand, synergistic effects were observed between FeOx and TiO2 and between H2O2 and TiO2 in the degradation of DCA.