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TiO2 thin films were deposited on woven stainless-steel mesh by pulsed DC magnetron sputtering, at room temperature without substrate bias or annealing. Woven stainless-steel mesh is inexpensive, flexible, semi-transparent and has a high surface area. This coating/substrate combination was selected for future photocatalytic reactor integration. The effect of operating pressure and magnetron power on coating crystallinity and photocatalytic activity were investigated. Results indicate that magnetron power is a key factor, as it affects the crystallinity and morphology of the thin films. A combination of low pressure and high-power lead to a one-step synthesis of TiO2 coatings with a mixed anatase and rutile phase. An optimised sample was produced and tested for methylene blue, methyl orange and rhodamine B decomposition under UV-A. Using various trapping agents, •OH and O2-• radicals were identified as the main photogenerated species responsible for the model pollutant degradation. Finally, durability tests revealed little to no photocatalytic performance deterioration after ten repeated cycles. This confirmed the suitability of this coating/substrate combination for future photocatalytic reactor integration. https://doi.org/10.1016/j.cviu.2017.00.000

The current work presents new and versatile photocatalytic surfaces designed to remove contaminants of emerging concerns (CECs) from water. Photocatalytic thin films of titanium dioxide (TiO2) were deposited on a polyethylene terephthalate (PET) surface (PET-TiO2) and photosensitized by a natural and non-hazardous curcumin (turmeric). The TiO2 thin film was deposited in a single stage and solvent-free process, without thermal post treatment, using the high power impulse magnetron sputtering (HiPIMS) technique. The photocatalytic film was characterized by different techniques (SEM/EDS, STEM, AFM, UV–Vis spectroscopy, and wettability via water droplet contact angle). The photocatalytic activity was assessed by the degradation of two model CECs: the fungicide carbendazim (CBZ), used in different crops around the world (coffee, rice, fruits, etc.), and the anthropogenic pollution tracer caffeine (CAF). Removal of these model CECs of up to 39% were achieved under combined UV and visible irradiation under 7 h photocatalytic treatments. The degradation process was further studied by dissolved organic carbon analysis, with up to 80% removal, and acute ecotoxicity tests with Aliivibrio fischeri, indicating reduction of toxicity or non-change. The PET-TiO2 surfaces remained stable for 5 consecutive cycles of use, with similar kinetic rates. Finally, the species involved in photocatalytic reactions were investigated by the use of h+, HO and O2− trapping agents, both in the presence and absence of turmeric. The results indicated that the addition of the turmeric led to an increase in photogenerated O2− radicals due to a synergistic effect between the photocatalyst and photosensitizer. The results demonstrate the potential of the PET-TiO2 surfaces as a straightforward solution for the removal of CECs from waters, using a flexible, scalable, reusable and environmental friendly photocatalytic material.

A range of different studies has been performed in order to design and develop photocatalysts that work efficiently under visible (and near-infrared) irradiation as well as to improve photons absorption with improved reactor design. While there is consensus on the importance of photocatalysis for environmental applications and the necessity to utilized solar irradiation (or visible-light) as driving force for these processes, it is not yet clear how to get there. Discussion on the future steps towards visible-light photocatalysis for environmental application is of great interest to scientific and industrial communities and the present paper reviews and discusses the two main approaches, band-gap engineering for efficient solar-activated catalysts and reactor designs for improved photons absorption. Common misconceptions and drawbacks of each technology are also examined together with insights for future progress.

In this study, a multistage treatment system was proposed to treat real pharmaceutical wastewater containing the antibiotic amoxicillin. Ozonation (O3), and ozonation combined with aerobic biodegradation, were performed. The real pharmaceutical wastewater presented a high concentration of organic matter (TOC: 803 mg C·L-1 and COD: 2775 mg O2·L-1), significant amoxicillin content (50 mg L-1) and acute ecotoxicity (Aliivibrio fischeri aTU: 48.22). Ozonation proved to be effective for amoxicillin degradation (up to 99%) and the results also indicated the removal of the original colour of the wastewater, with average consumption of 1 g of ozone. However, the ozonation system alone could not achieve complete mineralization. Therefore, a combination of ozonation and biodegradation in a multistage system was proposed in order to improve cost and treatment efficiency. The multistage treatment system presented promising results, achieving degradation of more than 99% of the amoxicillin, more than 98% of the original chemical oxygen demand (COD), and 90% of initial toxicity, with the consumption of approximately 500 mg of ozone. This indicates that this system could prevent dangerous and biorecalcitrant antibiotics from entering water resources.

In this study, photo-Fenton systems using visible light sources with iron and ferrioxalate were tested for the DOC degradation and decolorization of textile wastewater. Textile wastewaters originated after the dyeing stage of dark-colored tissue in the textile industry, and the optimization of treatment processes was studied to produce water suitable for reuse. Dissolved organic carbon, absorbance, turbidity, anionic concentrations, carboxylic acids, and preliminary cost analysis were performed for the proposed treatments. Conventional photo-Fenton process achieved near 99 % DOC degradation rates and complete absorbance removal, and no carboxylic acids were found as products of degradation. Ferrioxalate photo-Fenton system achieved 82 % of DOC degradation and showed complete absorbance removal, and oxalic acid has been detected through HPLC analysis in the treated sample. In contrast, photo-peroxidation with UV light was proved effective only for absorbance removal, with DOC degradation efficiency near 50 %. Treated wastewater was compared with reclaimed water and had a similar quality, indicating that these processes can be effectively applied for textile wastewater reuse. The results of the preliminary cost analysis indicated costs of 0.91 to 1.07 US$ m-3 for the conventional and ferrioxalate photo-Fenton systems, respectively. Graphical Abstract ᅟ.

In this work, the complexation of the hazardous β-lactamic antibiotic amoxicillin (AMX) with Fe3+ ions during coagulation was investigated. New bands in the ultraviolet-visible (UV-vis) spe...

In this work, ozone oxidation of the antibiotics amoxicillin (AMX), cephalexin, and ceftriaxone was investigated in different samples: (i) aqueous solutions (100 mg L−1), (ii) an industrial wastewater containing AMX at 125 mg L−1 (chemical oxygen demand 6000 mg O2 L−1), and (iii) a heavily contaminated industrial wastewater containing the antibiotics at a total concentration of 320 mg L−1. High performance liquid chromatography, molecular absorption spectrophotometry in the ultraviolet/visible region, and total organic carbon measurements showed that ozonation of antibiotics solutions led to removal higher than 95% with 10–20% mineralization. Industrial wastewater also showed very good efficiency for antibiotic removal (80–98%) after ozonation. Moreover, Microtox® test showed 86% toxicity reduction for the industrial wastewater.

Bismuth complex oxides, in particular, bismuth tungstate, have recently attracted attention as promising photocatalytic materials for water treatment processes. In the present work, photocatalytic bismuth tungstate films were prepared by pulsed direct current (DC) reactive magnetron sputtering of Bi and W targets in an Ar/O2 atmosphere onto spherically-shaped glass beads. The uniform coverage of the substrate was enabled by the use of oscillating bowl placed underneath the magnetrons. The atomic ratio of Bi/W was varied through the variation of the power applied to the magnetrons. The deposited coatings were analyzed by the scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), X-ray photoelectron spectroscopy and atomic force microscopy. The photocatalytic properties of the films were studied via the methylene blue (MB) degradation process under artificial (fluorescent light) and natural (sunlight) irradiation, and compared to the photocatalytic performance of titanium dioxide coatings deposited onto identical substrates. The results showed that the photocatalytic performance of bismuth tungstate and bismuth oxide-coated beads was superior to that exhibited by TiO2-coated beads. Overall, reactive magnetron co-sputtering has been shown to be a promising technique for deposition of narrow band gap bismuth-based semiconducting oxides onto irregularly-shaped substrates for potential use in water treatment applications.

– This study evaluates aerobic and anaerobic biodegradability and toxicity of a real pharmaceutical wastewater, which focuses on antibiotics production. Zahn-Wellens and Organization for Economic Cooperation and Development (OECD) methodologies were applied in order to verify the wastewater’s biodegradability and Microtox® analysis was performed for toxicity tests. Tests achieved more than 89% and 63% of Total Organic Carbon reduction, showing 80% and 50% of antibiotic removal, for aerobic and anaerobic processes, respectively. Moreover, acute ecotoxicological tests revealed that both techniques decreased the toxic character of real pharmaceutical wastewater. Desorption tests showed that the antibiotic was not degraded, but, in fact, adsorbed onto the sludge. Since biological treatment is the most widely used method for industrial wastewater treatment, this study indicates that this kind of treatment is probably unable to mineralize antibiotics present in pharmaceutical wastewaters, which may induce the development of resistant pathogens. Therefore, efforts must be taken to elucidate the main mechanisms of biological antibiotic removal from wastewaters since the presence of antibiotics in the environment is considered to be an emerging environmental issue.

É crescente a preocupação mundial com o desenvolvimento de tecnologias alternativas para o tratamento de águas residuárias direcionadas ao tratamento de efluentes complexos e reúso de águas. Neste sentido, o tratamento de efluentes por Processos Oxidativos Avançados (POA) configura-se como alternativa viável e eficiente na degradação de poluentes recalcitrantes. O POA Control – Grupo de Pesquisa e Aplicação de Processos Oxidativos Avançados no Controle da Poluição – foi criado no Departamento de Engenharia Sanitária e Ambiental(UFMG) para consolidar o desenvolvimento de tecnologias inovadoras para o tratamento de efluentes industriais de difícil degradação, com a publicação de várias teses, dissertações, artigos nacionais e internacionais e patentes. Este trabalho propõe revisar algumas das tecnologias desenvolvidas pelo grupo relacionando-as com o que vem sendo desenvolvido pela comunidade acadêmica internacional.

Antibiotics are considered emerging environmental issues and the presence of its traces in the environment can induce the development of resistant pathogens and promote allergies. Biological treatment is the most widely used method for industrial wastewater treatment, but it has been proved inefficient for the removal of all hazardous constituents of pharmaceutical products. In this context, the aim of this study is to evaluate the potential of aerobic biodegradation of organic matter present in real antibiotics production effluent using the method proposed by Zahn - Wellens. The organic matter degradation was monitored through periodic analysis of total organic carbon (TOC). After 28 days, the reactor achieved more than 80% of TOC removal, characterizing the wastewater as biodegradable, according to the used methodology.

RESUMO – O presente trabalho relata a construcao de um reator solar em escala piloto do tipo concentrador parabolico composto (CPC) a fim de ser utilizado para o tratamento alternativo de efluentes industriais reais por meio de reacoes fotocataliticas solares, do tipo foto-Fenton e fotocatalise com dioxido de titânio (TiO2). Nesse sistema, a energia solar e utilizada para aumentar a eficiencia da formacao dos agentes oxidantes a base de oxigenio, como os radicais hidroxila (OH), por meio de processos oxidativos avancados. Para a elaboracao do projeto do reator CPC os parâmetros de construcao: ângulo de aceitacao (θa), fator de concentracao da radiacao (Rc), material da superficie refletora, tubulacao do reator – material, espessura, diâmetro e ângulo de inclinacao do reator foram avaliados e definidos apos revisao bibliografica. Apos sua construcao e mediante licenca de instalacao e operacao, o foto reator solar foi instalado no terraco da Escola de Engenharia da UFMG. Testes inicias com efluente sintetico foram realizados no foto reator para a padronizacao experimental, com a utilizacao de um radiometro para a quantificacao da energia solar recebida durante as reacoes.

The textile industry is responsible for generating a large amount of a very complex wastewater during its production process. This wastewater contains residual dyes, high concentration of salt, soaps and detergents. Also, dyes used in the process are soluble in water, but not biodegradable and may be toxic for the environment. The present work proposes using advanced chemical oxidation (AOP) applying the photoFenton process in order to evaluate the feasibility of water reuse in the textile industry production process. Reactions were conducted in a bench photo-reactor with radiation, both UV and UV-vis and testing Iron Sulfate and Ferrioxalate as Iron (II) sources. Also, an experimental design was followed in which initial concentrations of Fe(II) and H2O2 varied from 4-20 mg/L and 100-500mg/l, respectively. Response variables monitored were TOC (mg/L) and residual H2O2 (mg/L). For a pH equals 3 in a molar rate of Fe/H2O2 ≈ 0,4:3, TOC reduction obtained was 98,4% and residual concentration of H2O2 was 2,6 mg/l. Results favor textile wastewater reuse after AOP treatment.

Os antibióticos têm ganhado cada vez mais destaque na comunidade técnica e acadêmica por serem considerados poluentes emergentes e perigosos. Uma crescente preocupação com o risco de potenciais efeitos ecotoxicológicos e de propagação de resistência bacteriana tem incentivado a realização de estudos da aplicação de processos oxidativos avançados para a degradação desse tipo de fármaco. A maior parte dos trabalhos apresentados na literatura estuda a degradação de soluções sintéticas de antibióticos sendo escassos os trabalhos que estudam a degradação desses compostos em efluentes reais. Nesse contexto, o presente trabalho objetiva o estudo da aplicação de processos oxidativos avançados e a conjugação com processos biológicos para o tratamento de um efluente real de produção de antibióticos de uma indústria farmacêutica. O efluente real estudado apresenta alta carga orgânica e alto teor de compostos antibióticos (como a amoxicilina e a cefalexina). Os ensaios de biodegradabilidade aeróbia e anaeróbia indicaram que, apesar de terem sidos considerados biodegradáveis, os efluentes foram considerados altamente tóxicos pelo teste de ecotoxicidade aguda. Os processos oxidativos avançados avaliados (Fenton, foto-Fenton/UV, ozonização e ozonização assistida com peróxido de hidrogênio) foram capazes de remover parte da matéria orgânica presente no efluente, alcançando até 69% de remoção da DQO pelo processo de foto-Fenton e até 99% de remoção da amoxicilina presente no efluente pelo processo de ozonização. Os POA avaliados também puderam remover parâmetros indesejados como a cor e o teor de compostos aromáticos dos efluentes. A toxicidade aguda testada com a bactéria Aliivibrio fischeri diminuiu após os tratamentos avaliados, mas ainda é considerada elevada. Nos estudos preliminares do processo de Fenton a coagulação com ferro III foi avaliada e se mostrou importante para a remoção dos antibióticos presentes no efluente, e a formação de complexos entre a amoxicilina e o ferro foi observada. A avaliação exploratória da combinação de processos oxidativos avançados com os processos biológicos e/ou com processos físico-químicos, como a coagulação, por exemplo, mostrou ser capaz de diminuir os custos operacionais envolvidos em mais de 50%, além de poder elevar as remoções de DQO até 98,5% e facilitar, assim, a implantação dos processos estudados em escala industrial. Antibiotics have gained increasing distinction in the academic community because they are considered emerging and dangerous pollutants. A growing concern about the risk of potential ecotoxic effects and spread of bacterial resistance has encouraged researches to study the application of advanced oxidation processes for the degradation of this type of drug. However, most of the works presented in the literature studies the degradation of synthetic antibiotic solutions and few papers study the degradation of these compounds in real wastewaters. In this context, this study aims to inquiry the application of advanced oxidation processes as well as their combination with biological processes for the treatment of a real wastewater from the production of antibiotics of a pharmaceutical industry. The real wastewater studied has high organic matter content and high levels of antibiotic compounds. Aerobic and anaerobic biodegradability assays indicated that, despite considered biodegradable, wastewaters were proved to be highly toxic after acute ecotoxicity tests. Advanced oxidation processes assessed (Fenton, photo-Fenton/UV, ozonation and ozonation assisted with hydrogen peroxide) were able to remove some of the organic matter present in the wastewater, reaching up to 69 % of COD removal by the photo- Fenton process and up to 99% of amoxicillin removal by the ozonation process. The evaluated AOP could also remove unwanted parameters such as color and aromatics content. Acute toxicity tested with Aliivibrio fischeri bacteria decreased after the treatments, but it is still considered high. In preliminary studies involving Fenton process, coagulation with iron III was evaluated and proved to be important for the removal of antibiotics present in the wastewater. Also, the formation of complexes between iron and amoxicillin was observed. The exploratory evaluation of the combination of advanced oxidation processes with biological processes and/or physical- chemical processes, such as coagulation, for example, proved to be able to decrease operational costs in more than 50% , in addition to raising COD removals up to 98.5% and, thereby, enabling the implementation of the studied processes in industrial scale.

Several studies have reported the adverse effects of recalcitrant compounds and emerging contaminants present in industrial effluents, which are not degradable by ordinary biological treatment. Many of these compounds are likely to accumulate in living organisms through the lipid layer. At concentrations above the limits of biological tolerance, these compounds can be harmful to the ecosystem and may even reach humans through food chain biomagnification. In this regard, advanced oxidation processes (AOPs) represent an effective alternative for the removal of the pollutants. This study focused on the AOP involving the use of ultraviolet radiation in homogeneous and heterogeneous systems. Based on the literature review, comparisons between natural and artificial light were established, approaching photoreactors constructive and operational characteristics. We concluded that the high availability of solar power in Brazil would make the implementation of the AOP using natural solar radiation for the decontamination of effluents feasible, thereby contributing to clean production and biodiversity conservation. This will serve as an important tool for the enforcement of environmental responsibility among public and private institutions.