Microalgal Bioassays as a Test of Pesticide Photodegradation Efficiency in Water

Xunta de Galicia; XUGA 10307A9

Study on the Photocatalytic Degradation of Oxytetracycline by Graphene/TiO2/Zeolite compounds

环氧四环素(Oxytetracycline，OTC)又称土霉素，属于四环素类广谱抗生素，作为抗菌剂和饲料添加剂被广泛地应用于人类和动物，具有潜在的生态毒性，目前尚未找到一种理想而有效的处理方法。本研究采用光催化氧化法对其进行光催化降解实验。TiO2以其化学稳定性、无毒性、价格低廉、光催化活性高等优异性能被广泛研究。但因其颗粒过小，易团聚，不易与水分离，吸附能力差，需紫外光激发而受到限制。 本研究以具有大表面、高吸附性能的沸石为载体，以具有优异的导电性能、较高的比表面积、可最大限度地拓展光催化剂对可见光的响应范围的石墨烯掺杂，采用固态分散法制备石墨烯/二氧化钛/沸石(Graphene/TiO2...Oxytetracycline(OTC), an important member of tetracycline and is popularly used in humans and animals, which is reported to be a toxic threat to the ecosystem. It is important to find the treatment method which has high removal efficiency for actual use since OTC are not biodegradable. In this study, the photocatalysis was used to degrade the OTC. TiO2 is a promising photocatalyst which is stable...学位：理学硕士院系专业：环境与生态学院_生态学学号：3332013115170

Evaluation of Toxicity on Ctenopharyngodon idella Due to Tannery Effluent Remediated by Constructed Wetland Technology

Aquatic pollution caused by industrial effluents is an environmental issue, imposing deleterious impacts on the overall environment, specifically, on humans, by disrupting the balance of the ecosystem. Among all the industries, tanneries are considered some of the most polluting due to heavy use of toxic organic and inorganic compounds during leather processing, most of which find their way into rivers, lakes, and streams, thus exerting adverse effects on aquatic life, particularly on fish. Considering the huge concentrations of pollutants present in tannery effluents, toxicity evaluation is of prime importance. Therefore, bioassays are usually employed to assess the acute toxicity of industrial effluents and efficiency of effluent clean-up technologies as they provide a thorough response of test species to the substances present in the tested media. In the present study, the toxic effects of tannery effluent on common grass carp (Ctenopharyngodon idella) were studied for 96 h in laboratory conditions. The effluent was added at different concentrations, before and after treatment by constructed wetlands (CWs). During this period, mortality data was collected to calculate the 96 h-LC50 (lethal concentration inducing 50% mortality) and acute toxicity of C. idella. In addition to this, observations on change in morphological, physiological, and behavioural patterns were also made every 24 h. The present toxicity assay revealed that the raw tannery effluent changed the morphology, physiology, and behavioural response of fish. Moreover, fish exposure to raw/untreated effluent caused high acute toxicity and 100% mortality, due to the presence of high concentrations of salts and chromium (Cr) metal. While treatment of tannery effluent by CWs vegetated with different plants (B. mutica, L. fusca, and T. domingensis) significantly reduced its toxicity and fish mortality as well, and inoculation of salt and Cr-tolerant endophytic bacteria (Enterobacter sp. HU38, Microbacterium arborescens HU33, and Pantoea stewartii ASI11) further reduced (up to 90%) its toxicity level. Hence, the use of CWs for tannery effluent treatment can be recommended to favour public health and promote the overall safety of the environmentThis research was conducted under the grant number, No. 20-3854/R&D/HEC/14., of the Higher Education Commission (HEC), PakistanS

Green Surface-washing Agent and Oily Waste Management for Oil Spill Response

Oil spills in the marine environment frequently reach the coastal zone where active cleanup strategies may become necessary if the rates of natural weathering and attenuation of the stranded oil are considered inadequate. The application of surface-washing agents (SWAs) is an operational technique that enhances the separation and removal of oil that is adhered to solid surfaces. This study presents a comprehensive review of the current and emerging technologies to treat oiled shorelines using SWAs. The literature review includes a brief description of the characteristics of shoreline oiling and the current available techniques for shoreline treatment or cleanup. It summarizes the basics of surface washing and state-of-the-art efforts to date on oil removal using SWAs at both laboratory and field scales. The development trends of green SWAs for shoreline treatment are further introduced. To develop the novel green SWA, the use of nanocellulose-based nanofluid as a SWA was studied by investigating its reactivity and effectiveness. Salinity was found to be the most influencial factor to facilitate oil removal with the nanofluids. Cations from salt can promote the adsorption of nanocellulose on the oil/water interface by reducing the surface charges. The experimental results revealed the nanocellulose could be effective at low concentrations but an excess of nanocellulose hindered oil removal due to an increase in fluid viscosity. The biotoxicity tests showed that nanocellulose-based nanofluid did not have negative effects on algae growth and introducing nanocellulose into an oiled culture medium can actually mitigate the toxicity of the oil on algae. A comparison in removal efficiency with other surfactants demonstrated the potential value for shoreline cleanup due to the superior effectiveness of nanocellulose-based nanofluids. It was found that the nanocellulose has a high potential for application as a surface-washing agent for shoreline cleanup due to the low cost, low toxicity, and high efficiency. In addition, the shoreline cleanup operation can generate large amount of oily waste which requires further treatment. It is necessary to develop a programming model for oily waste management. An inexact chance-constrained programming model (ICCP) was developed with the consideration of uncertain environments, which cannot only consider the probability distribution of random variable but also interval parameters. The developed model was applied to a hypothetical oily waste management system. The interval solutions obtained from ICCP model included facilities selection, waste flow allocations, and expected time length under different constraint-violation risks. It is an effective tool to minimize the system cost of oily waste management with uncertainties. The obtained solutions could support the managers for the trade-off between system cost and risk level

Evaluation of the biotoxicity potential of water from the Kovin Dunavac marina (Kovin, Serbia) to Aliivibrio fischeri

This research aimed to assess the biotoxicity of water from the Kovin Dunavac marina to Aliivibrio fischeri

Efficiency Evaluation of a wastewater Treatment Plant by Activated Sludge

Abstract: Performance of El-Agamyeen Plant for wastewater treatment (WWTP) by activated sludge was studied over a period of 20 weeks. Results showed that chemical oxygen demand; COD, biochemical oxygen demand; BOD, total suspended solids; TSS and ammonia decreased through stages of treatment process. The percentage removal of these parameters during studied period ranged 86-95, 91-96, 90-94 and 71-85 % respectively. Dissolved oxygen; DO in aeration tank was not less than 1.2 mg/L during study. Of microfauna, amoebae and flagellates appeared at low DO and high organic load, dominancy of crawling and stalked ciliates affected efficiency of treatment. Rotifers count ranged from 1.3x10 3 to 9x10 4 indicating good sludge quality.High toxicity could be obtained with the inlet wastewater and decreased with mixed liquor; the outlet water has been shown the least average toxic effects (<10% mortality) on the test organism. The results indicated that wastewater treatment in this Plant during the study period reduced pollution significantly and effluent water can be left for discharge into water bodies

Produção de óxidos porosos contendo nanopartículas de prata via anodização em ligas metálicas de alumínio para aplicações médicas

No trabalho em questão propôs-se uma nova forma de produção de liga metálica contendo nanopartículas de prata para aplicações na área da saúde. A liga metálica utilizada foi o alumínio e as nanopartículas de prata foram embidas em um óxido poroso através de anodização. A liga Al-Ag foi produzida com composição de 10% de prata em peso. Posteriormente foi realizada uma laminação a frio e as tiras foram solubilizadas a 550ºC por 5h e temperadas em água. Com este tratamento térmico espera-se a completa dissolução da prata e manutenção da solução sólida na temperatura ambiente (liga supersaturada Al-10%Ag). A obtenção de nanopartículas embebidas em matriz porosa de alumina foi realizada por anodização em ácido oxálico com uma densidade de corrente de 50mA/cm² e durante 15 minutos, procedeu-se em temperatura ambiente. Foi obtida uma camada de óxido porosa com cerca de 30µm. A análise elementar da superfície da amostra por EDS com tensões crescentes observou-se que a concentração de prata na superfície é maior se comparada com a concentração no interior da amostra. A superfície apresenta uma concentração de aproximadamente 27% em peso de prata Através de análises de MEV-FEG e MET foi possível observar morfologia da formação dos poros, nanotubos formados durante anodização e nanopartículas de prata. Os poros apresentam em média 85 nm na região analisada, e a distância de parede apresenta 50 nm em média. As partículas de prata na região analisada apresentam valores de 3 a 40nm. O teste de biotoxidez realizado com inoculação de bactérias Escherichia coli em biofilme comprova a eficiência das nanopartículas de prata contra esses organismos patológicos quando comparado com biofilme formado em uma amostra de alumínio comercial.In the present work, a new way production of alloy containing silver nanoparticles for health applications was proposed. The alloy used was aluminum and the silver nanoparticles were embedded in a porous oxide through anodization. The Al-Ag alloy was produced with a composition of 10% silver weight. Afterwards a cold rolling was carried out and the strips were solubilized at 550ºC for 5h and quenched in water. With this heat treatment the complete dissolution of the silver and maintenance of the solid solution at room temperature (Al-10% Ag supersaturated alloy) is expected. The obtained surface fixed nanoparticles embedded in porous alumina matrix was made by porous anodizing in oxalic acid. Galvanostatic anodization with a current density of 50mA/cm² for 15 minutes was carried out at room temperature. A porous oxide layer around 30μm was obtained. Elementary analysis at the surface of the sample by EDS increasing potencial has observed that the concentration of silver on the surface is higher as compared to the concentration inside the sample. The surface has a concentration of approximately 27% silver weight. Through MEV-FEG and MET analyzes, it was possible to observe morphology of pore formation, nanotubes formed during anodization and silver nanoparticles. The pores average has 85 nm in the analyzed region, and the wall distance average has 50 nm. The silver particles in the analyzed region have values ranging from 3 to 40nm. The biotoxicity test performed with inoculation of Escherichia coli bacteria in biofilm proves the efficiency of silver nanoparticles against these pathological organisms when compared to biofilm formed in a commercial aluminum sample

Function of a landscape lake in the reduction of biotoxicity related to trace organic chemicals from reclaimed water

© 2016 The storage of water in a landscape lake can act as a buffer zone between reclaimed water production and reuse, but there is still uncertainty about the variation of water quality and toxic effects during the open-storage process. In this study, long-term sample collection, chemical analyses and biotoxicity assessments were conducted on reclaimed water before and after open storage in a landscape lake. The organic contents, in terms of chemical oxygen demand and total organic carbon, were found to be slightly higher in the lake water than that in the reclaimed water, but substantial reduction of the total concentration of 52 trace organic chemicals was obtained and microorganism toxicity, phytotoxicity, aquatic vertebrate toxicity and genotoxicity, were significantly weakened after open storage. Furthermore, the total risk quotient (RQTotal) decreased from 5.12 (potential ecological risk level) in the reclaimed water to 0.18 (negligible ecological risk level) in the lake water. The removal of chlorpyrifos, dichlorphos and tetracycline was identified as the main reason for biotoxicity reduction after open storage. The seminatural environment of the landscape lake would have provided a favorable condition for the decay of toxic trace organic chemicals so that the stored water turned to be safer for further reuse