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Alkali-activated foams are ceramic-like materials prepared at near-ambient temperature. This study investigates them for point-of-use water disinfection, thus providing an alternative to ceramic filters fired at a high temperature. Alkali-activated foams with different compositions were characterized for the porosity, mechanical strength, shrinkage, and microstructure. The optimized foam, employing metakaolin as the raw material, was coated with a colloidal Ag solution. The disinfection performance and leaching behavior of the foams was followed in a continuous 10 week experiment, where clean water with a weekly pulse of contaminated water was distributed through the foam. The average inactivation of Escherichia coli with the Ag-coated foam was 2.84 log10, which was 1.27 units higher compared to foam without Ag. A quantitative polymerase chain reaction analysis and metagenomic sequencing verified that foams with and without Ag were both capable of reducing the microbial load. Furthermore, the changes induced by the foam with Ag on the microbial community composition, antibiotic resistome, and metal and biocide resistomes were significant. The leached concentrations of Ag, Na, Si, and Al were in accordance with the drinking water guidelines. Finally, a life cycle assessment indicated the possibility of reducing the global warming potential and the total embodied energy in comparison with a conventional ceramic filter., Materials and Environment

This work reports the application of photocatalytic disinfection to the inactivation of Acanthamoeba trophozoites, a free-living pathogenic amoeba. Two types of photocatalytic reactors configurations have been used: i) a slurry reactor using suspended titanium dioxide (TiO2); and, ii) a fixed-bed reactor using immobilized TiO2 onto glass Raschig rings. The effect of the chemical composition of water has been analysed, comparing the efficiency of the process in deionized water (DW) and synthetic wastewater treatment plant effluent (SWTPE). The inactivation of Acanthamoeba spp. has been compared to that of Escherichia coli bacteria, being also analysed the concomitant inactivation of both microorganisms. Our results show that 99% of inactivation of E. coli and Acanthamoeba spp. can be achieved using photocatalysis in both reactor configurations, but interestingly, the kinetics of inactivation of both microorganisms together differs from that found with them separately. Particularly, E. coli seems to be more resistant to the inactivation in the presence of Acanthamoeba spp. which has been justified by the screen effect caused by the bigger size of Acanthamoeba spp. This observation is more pronounced in DW as the composition of the SWTPE prevent the microorganisms from suffering osmotic and/or mechanical stress and protect cellular structures to the attack of reactive oxygen species (ROS). On the other hand, the difference between the inactivation rate of E. coli and Acanthamoeba, points out the importance of the different inactivation mechanisms, suggesting that the entry of small TiO2 particles into the cytoplasm of the Acanthamoeba cells provokes the attack of inner structures and as a consequence a faster inactivation. This mechanism is not possible when the catalyst is immobilized leading to a higher cell resistance to inactivation and consequently lower efficiency of the disinfection process., Spanish State Research 536 Agency (AEI), Spanish Ministry of Economy and Competitiveness (MINECO), Comunidad de Madrid, Fundación Universitaria San Pablo CEU, Instituto de Salud Carlos III, Depto. de Química Inorgánica, Fac. de Ciencias Químicas, TRUE, pub

Very Important Paper, Singlet molecular oxygen (1O2) is a potent electrophile and a strong oxidizing agent and can be easily generated by photosensitization via illumination of appropriate dyes with visible light. This short-lived reactive oxygen species is able to photooxidize many electron-rich organic compounds and, therefore, 1O2 can damage many cellular components, such as membrane lipids, proteins and DNA, causing the photoinactivation of microorganisms in water. This Review summarises the most relevant work to date on solar water disinfection by photocatalytic 1O2 production, using photosensitizing materials suitable for their use in solar reactors for water treatment. The prototypes were equipped with compound parabolic collectors of sunlight and designed for point-of-use water treatment. The choice of the type of dye (RuII complexes or fullerenes) and polymeric support for the preparation of the 1O2 photosensitizing material, as well as the most important photophysical and operational parameters to be optimized to achieve efficient water disinfection with solar reactors, will be discussed., Depto. de Química Orgánica, Fac. de Ciencias Químicas, TRUE, pub

A multitude of extrinsic environmental factors (referred to in their entirety as the ‘skin exposome’)impact structure and function of skin and its corresponding cellular components. The complex (i.e. additive, antagonistic, or synergistic) interactions between multiple extrinsic (exposome) and intrinsic (biological) factors are important determinants of skin health outcomes. Here, we have investigated the role of hypochlorous acid (HOCl) as an emerging component of the skin exposome serving molecular functions as an innate immune factor, environmental toxicant, and topical chemopreventive agent targeting solar UV-induced skin cancer. Our studies have explored the interaction between solar UV and HOCl-related environmental co-exposures identifying a heretofore unrecognized photo-chemopreventive activity of topical HOCl and chlorination stress that blocks inflammation and tumorigenic progression in UV-induced high-risk SKH-1 mouse skin, a finding in contrast with the pro-inflammatory and UV-enhancing effects of topical trichloroisocyanuric acid (TCIC), a common chloramine-type freshwater disinfectant. These observations on epithelial health and chlorination stress, explored for the first time in the context of skin exposure to chlorinated fresh water used for swimming pool disinfection, indicate a heretofore unrecognized role of chlorination stress as an environmental determinant of human epithelial health. We also demonstrate that reconstructed human gingiva (EpiGingivalTM), a gastrointestinal tissue with remarkable histological similarity to stratified skin, is subject to topical HOCl/TCIC-induced chlorination stress as a result of exposure to environmentally relevant dose regimens. Given the daily exposure of billions of people to chlorinated fresh water, our findings deserve future examinations that define cutaneous and gastrointestinal epithelial effects of freshwater chlorination relevant to human populations on a global scale.

Treatment with ultraviolet (UV) light is a common option for inactivating waterborne organisms. The mercury vapor lamps conventionally used as a source of UV-C light for water disinfection are eventually replaced by light emitter diodes (LEDs) in the middle term due to their higher efficiency and lack of hazardous materials. Nonetheless, biological mechanisms for repairing UV damage caused by the UV treatment are some of its significant undesirable features. The objective of this study is to evaluate and compare the UV-resistance and the reactivation degree in different strains of E. coli and E. faecalis treated with a flow-through reactor equipped with LEDs with an emission range between 265 and 285 nm. The treated organisms were subjected to various illumination regimes after the UV irradiation. The results obtained indicated that intraspecific differences between the strains of E. coli were greater than the interspecific differences with respect to E. faecalis in terms of UV-resistance and repairing potential. The UV doses necessary to achieve four log-reductions ranged from 10.2 to 16.3 mJ cm−2 for E. coli and from 11.1 to 11.4 for mJ cm−2 for E. faecalis. Dark repair was not observed within 24 h after the UV irradiation whereas the degree of photorepair depended on both the bacteria strain and the applied UV dose. The exposure of the irradiated organisms to an illuminated environment entailed and increasing between the 18 % and the 160 % of the UV dose required to achieve four log-reductions.

The heterogeneous copper and cobalt catalysts (CoNPs-hybrid and CuNPs-hybrid) were synthesized using a protein-directed method to obtain catalytically active nanoparticles for wastewater disinfection, and fully characterized by ICP-OES, XRD, XPS, TEM and SEM analysis. CuNPs-hybrid demonstrated antibacterial capabilities, total removal of Enterococcus sp. (≈ 5-log reduction (LR)) in 120 min, at a concentration of 0.1 g/L, and efficient recyclability, by retaining this removal efficiency in the third cycle. Therefore, its high recyclability, low use of additional reagents, the sustainable nature of its synthesis, and high catalytic efficiency make this material a potentially attractive disinfectant. However, the opposite behavior was observed for the CoNPs-hybrid case, without disinfectant capabilities by its own. While with a Turnover Frequency (TOF) of the CoNPs-hybrid, of 1.84 h−1, and 99.9 % degradation of pAP in 30 min, the analysis demonstrated the catalytic capacity of the CoNPs-hybrid. Therefore, the intensification of the process was performed adding peroxymonosulfate (PMS) and solar radiation. It was achieved a 2.5-LR disinfection rate in 120 min at a concentration of 0.05 g/L when activated by solar radiation, but it is still less than that obtained with external actors on an individual basis. X-ray diffraction showed that the catalyst composition is not stable throughout use, which is reflected in its low recyclability. © 2023 The Authors

Effective and cheap water purification is one of the most important tasks facing humanity. Among various methods of water treatment, heterogeneous photocatalysis is probably most recommended. However, the application of artificial sources of irradiation results in high investment and operating costs. Accordingly, either vis-responsive photocatalysts or different ways of photocatalyst activation should be developed. In the present study, rotating magnetic field (RMF) has been tested to inactivate gram-positive (Staphylococcus epidermidis) and gram-negative (Escherichia coli) bacteria in the presence of pristine and Pt-modified titania P25 photocatalyst. Liquid cultures of the bacteria have been exposed to the titania and RMF (RMF frequency of 1–50Hz, RMF magnetic induction of ca. 19.92 mT, 180min exposure time, temperature of incubation at 37°C). It has been found that highly active titania photocatalyst might also work in the absence of photoirradiation but under RMF. Moreover, its modification with platinum besides highly improved photocatalytic activity (tested for two model reactions of oxidative decomposition of acetic acid and anaerobic dehydrogenation of methanol under UV/vis irradiation) results in significant enhancement of antimicrobial effect under RMF. Additionally, photocatalysts with larger content of oxidized forms of platinum show higher antimicrobial activity, and thus it is proposed that platinum oxides are more active than zero-valent platinum under RMF. This study provides evidence of antimicrobial effect of titania without photoirradiation, indicating that RMF might efficiently activate photocatalyst.

Providing clean drinking water is a great challenge worldwide, especially for low-income countries where the access to safe water is limited. During the last decade, new biotechnological approaches have been explored to improve water management. Among them, the use of antimicrobial nanoparticles for designing innovative centralized and decentralized (point-of-use) water treatment systems for microbial decontamination has received considerable attention. Herein, antimicrobial lignin capped silver nanoparticles (AgLNP) were embedded on residual cork pieces using high-intensity ultrasound coupled with laccase-mediated grafting to obtain biofunctionalized nanomaterial. The developed AgLNP-coated cork proved to be highly efficient to drastically reduce the number of viable Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus in liquid medium. Additionally, the coated-cork was characterized using FTIR-ATR spectroscopy and SEM imaging, and further used as a filter bed in a point-of-use device for water disinfection. The constructed water filtering system significantly reduced the amount of viable E. coli and resistant Bacillus cereus spores from filtered water operating at increasing residence times of 1, 4, 6, 16, 24, and 48 h. Therefore, the presented results prove that the obtained cork-based antimicrobial nanocomposite material could be used as a filtering medium for the development of water filtration system to control pathogen dissemination., Peer Reviewed, Postprint (published version)

Effective and cheap water purification is one of the most important tasks facing humanity. Among various methods of water treatment, heterogeneous photocatalysis is probably most recommended. However, the application of artificial sources of irradiation results in high investment and operating costs. Accordingly, either vis-responsive photocatalysts or different ways of photocatalyst activation should be developed. In the present study, rotating magnetic field (RMF) has been tested to inactivate gram-positive (Staphylococcus epidermidis) and gram-negative (Escherichia coli) bacteria in the presence of pristine and Pt-modified titania P25 photocatalyst. Liquid cultures of the bacteria have been exposed to the titania and RMF (RMF frequency of 1–50Hz, RMF magnetic induction of ca. 19.92 mT, 180min exposure time, temperature of incubation at 37°C). It has been found that highly active titania photocatalyst might also work in the absence of photoirradiation but under RMF. Moreover, its modification with platinum besides highly improved photocatalytic activity (tested for two model reactions of oxidative decomposition of acetic acid and anaerobic dehydrogenation of methanol under UV/vis irradiation) results in significant enhancement of antimicrobial effect under RMF. Additionally, photocatalysts with larger content of oxidized forms of platinum show higher antimicrobial activity, and thus it is proposed that platinum oxides are more active than zero-valent platinum under RMF. This study provides evidence of antimicrobial effect of titania without photoirradiation, indicating that RMF might efficiently activate photocatalyst.

Effective and cheap water purification is one of the most important tasks facing humanity. Among various methods of water treatment, heterogeneous photocatalysis is probably most recommended. However, the application of artificial sources of irradiation results in high investment and operating costs. Accordingly, either vis-responsive photocatalysts or different ways of photocatalyst activation should be developed. In the present study, rotating magnetic field (RMF) has been tested to inactivate gram-positive (Staphylococcus epidermidis) and gram-negative (Escherichia coli) bacteria in the presence of pristine and Pt-modified titania P25 photocatalyst. Liquid cultures of the bacteria have been exposed to the titania and RMF (RMF frequency of 1–50 Hz, RMF magnetic induction of ca. 19.92 mT, 180 min exposure time, temperature of incubation at 37 °C). It has been found that highly active titania photocatalyst might also work in the absence of photoirradiation but under RMF. Moreover, its modification with platinum besides highly improved photocatalytic activity (tested for two model reactions of oxidative decomposition of acetic acid and anaerobic dehydrogenation of methanol under UV/vis irradiation) results in significant enhancement of antimicrobial effect under RMF. Additionally, photocatalysts with larger content of oxidized forms of platinum show higher antimicrobial activity, and thus it is proposed that platinum oxides are more active than zero-valent platinum under RMF. This study provides evidence of antimicrobial effect of titania without photoirradiation, indicating that RMF might efficiently activate photocatalyst.

The frequent outbreaks of foodborne and waterborne diseases have become a serious public health issue, which is related to the presence of microbial biofilms on surfaces of materials. Current research activities aiming at reducing or eliminating the biofilm formation could be mainly divided into two major approaches: an active approach of “attacking”, by killing the microbes once they are attached to the material surface; and a passive approach of “defending”, creating resistance to microbial attachment or releasing the attached one. In this dissertation, a dual-functional structure was initially proposed: rechargeable biocidal moieties immobilized at the inner layer, and antifouling moieties serving as a protective layer located on the outside of the surface. With a such unique surface structure, once microorganisms approach the designed surfaces, (i) the antifouling moieties could reduce the non-specific adsorption of the microorganisms and make them difficult to adhere; (ii) any live bacteria attached on the surface could be immediately killed by the incorporated biocidal moieties; (iii) any resulting cell debris and other biofoulants could be easily washed off with mild hydrodynamic force applied; furthermore, (iv) the consumed biocidal activity could be regenerated by either chlorination or photoirradiation. Overall, I designed and successfully developed three types of rechargeable biocidal and antifouling functional materials, which exhibited great potentials in food packaging, water filtration, and medical application areas.Specifically, in this dissertation, chapter 1 briefly introduces processes and mechanisms of microbial biofilm formation, two major strategies responding to avoid and reduce the formation of biofilm, and typical chemicals with rechargeable biocidal or antifouling functions applied in recent years. In chapter 2, a new antibiofilm concept combining both rechargeable antimicrobial and antifouling functions was proposed. An N-halamine precurso

Biocorrosion is a phenomenon that strongly affects the integrity of the materials used in the oil and gas industry. Different types of biocides are currently used to control bacteria in industrial water; however, they have disadvantages such as microbial resistance to these chemical compounds and possible impact on biodiversity due to eventual contamination of natural water. There are several alternatives for the elimination or control of bacteria, among which one is the use of type C ultraviolet (UV-C) radiation. Nevertheless, the use of these micro-organism removal systems could be affected by water quality and its efficiency can be improved by using LED diodes of lower energy consumption and greater versatility in exposure to high temperatures. This work was aimed to evaluate the use of such radiation as a strategy for the control and/or elimination of sulfate reducing bacteria (SRB), and acid producing bacteria (APB) present in both corrosion and souring processes. For this purpose, injection water from oil and gas industry and a dynamic system which flow variation enabled the evaluation of different water exposure times to UV-C light (1-20 minutes) were used. Efficiencies ranging between 99-100% were achieved in the elimination of SRB and APB from produced water measured by two different techniques, selective culture media for these microbial populations, and qPCR detecting a specific gene from the SRB population., La biocorrosión es un fenómeno que afecta en gran medida la integridad de los materiales utilizados en la industria del Petróleo. Diferentes tipos de biocidas son utilizados actualmente para el control de bacterias en aguas industriales, sin embargo, presentan una serie de inconvenientes, tales como: resistencia microbiana a dichos compuestos químicos y posible afectación de la biodiversidad por eventual contaminación de aguas naturales. Existen otras alternativas para la eliminación o el control de microorganismos entre las cuales está el uso de la radiación ultravioleta tipo C. No obstante, el uso de estos sistemas de eliminación de microorganismos se ve afectado por la calidad del agua y su eficiencia puede ser mejorada utilizando diodos tipo LED de menor consumo energético y mayor versatilidad en la exposición a altas temperaturas. El propósito de este trabajo fue evaluar el uso de dicha radiación como estrategia en el control y/o eliminación de bacterias asociadas a procesos de corrosión y agriamiento (BSR y BPA). Usando aguas de inyección y un sistema dinámico con variación del flujo se evaluaron diferentes tiempos de exposición del agua a la luz UV-C (1-20 minutos). Se obtuvieron eficiencias entre 99-100% en la eliminación de bacterias BSR y BPA medidas por dos técnicas diferentes, usando medios de cultivo selectivos para estas poblaciones microbianas y usando qPCR para detectar un gen específico de la población BSR.

Clean drinking water is a vital part of our society and a basic human right. With an ever growing population and a decreasing quality of raw water, new methods need to be introduced to keep up with the demand for clean, biostable, and sustainable production of drinking water. The aim of this study is to evaluate Håbo municipality’s increasing usage of chemicals in their water treatment process and to investigate current and future possible technologies for water treatment for Håbo to make their process more sustainable. In this study four scenarios of different cost and change of today’s water treatment plants are presented, while our overall recommendation is to build a new facility. A new plant with new treatment methods such as ultrafiltration is most in line with Håbo municipality’s vision of decreasing chemical usage and sustainability, all while maintaining the water quality. Due to Håbo’s growing population and today’s water plants running close to maximum capacity, a new facility with a larger capacity should be considered.

The frequent outbreaks of foodborne and waterborne diseases have become a serious public health issue, which is related to the presence of microbial biofilms on surfaces of materials. Current research activities aiming at reducing or eliminating the biofilm formation could be mainly divided into two major approaches: an active approach of “attacking”, by killing the microbes once they are attached to the material surface; and a passive approach of “defending”, creating resistance to microbial attachment or releasing the attached one. In this dissertation, a dual-functional structure was initially proposed: rechargeable biocidal moieties immobilized at the inner layer, and antifouling moieties serving as a protective layer located on the outside of the surface. With a such unique surface structure, once microorganisms approach the designed surfaces, (i) the antifouling moieties could reduce the non-specific adsorption of the microorganisms and make them difficult to adhere; (ii) any live bacteria attached on the surface could be immediately killed by the incorporated biocidal moieties; (iii) any resulting cell debris and other biofoulants could be easily washed off with mild hydrodynamic force applied; furthermore, (iv) the consumed biocidal activity could be regenerated by either chlorination or photoirradiation. Overall, I designed and successfully developed three types of rechargeable biocidal and antifouling functional materials, which exhibited great potentials in food packaging, water filtration, and medical application areas.Specifically, in this dissertation, chapter 1 briefly introduces processes and mechanisms of microbial biofilm formation, two major strategies responding to avoid and reduce the formation of biofilm, and typical chemicals with rechargeable biocidal or antifouling functions applied in recent years. In chapter 2, a new antibiofilm concept combining both rechargeable antimicrobial and antifouling functions was proposed. An N-halamine precurso

Biocorrosion is a phenomenon that strongly affects the integrity of the materials used in the oil and gas industry. Different types of biocides are currently used to control bacteria in industrial water; however, they have disadvantages such as microbial resistance to these chemical compounds and possible impact on biodiversity due to eventual contamination of natural water. There are several alternatives for the elimination or control of bacteria, among which one is the use of type C ultraviolet (UV-C) radiation. Nevertheless, the use of these micro-organism removal systems could be affected by water quality and its efficiency can be improved by using LED diodes of lower energy consumption and greater versatility in exposure to high temperatures. This work was aimed to evaluate the use of such radiation as a strategy for the control and/or elimination of sulfate reducing bacteria (SRB), and acid producing bacteria (APB) present in both corrosion and souring processes. For this purpose, injection water from oil and gas industry and a dynamic system which flow variation enabled the evaluation of different water exposure times to UV-C light (1-20 minutes) were used. Efficiencies ranging between 99-100% were achieved in the elimination of SRB and APB from produced water measured by two different techniques, selective culture media for these microbial populations, and qPCR detecting a specific gene from the SRB population., La biocorrosión es un fenómeno que afecta en gran medida la integridad de los materiales utilizados en la industria del Petróleo. Diferentes tipos de biocidas son utilizados actualmente para el control de bacterias en aguas industriales, sin embargo, presentan una serie de inconvenientes, tales como: resistencia microbiana a dichos compuestos químicos y posible afectación de la biodiversidad por eventual contaminación de aguas naturales. Existen otras alternativas para la eliminación o el control de microorganismos entre las cuales está el uso de la radiación ultravioleta tipo C. No obstante, el uso de estos sistemas de eliminación de microorganismos se ve afectado por la calidad del agua y su eficiencia puede ser mejorada utilizando diodos tipo LED de menor consumo energético y mayor versatilidad en la exposición a altas temperaturas. El propósito de este trabajo fue evaluar el uso de dicha radiación como estrategia en el control y/o eliminación de bacterias asociadas a procesos de corrosión y agriamiento (BSR y BPA). Usando aguas de inyección y un sistema dinámico con variación del flujo se evaluaron diferentes tiempos de exposición del agua a la luz UV-C (1-20 minutos). Se obtuvieron eficiencias entre 99-100% en la eliminación de bacterias BSR y BPA medidas por dos técnicas diferentes, usando medios de cultivo selectivos para estas poblaciones microbianas y usando qPCR para detectar un gen específico de la población BSR.

Clean drinking water is a vital part of our society and a basic human right. With an ever growing population and a decreasing quality of raw water, new methods need to be introduced to keep up with the demand for clean, biostable, and sustainable production of drinking water. The aim of this study is to evaluate Håbo municipality’s increasing usage of chemicals in their water treatment process and to investigate current and future possible technologies for water treatment for Håbo to make their process more sustainable. In this study four scenarios of different cost and change of today’s water treatment plants are presented, while our overall recommendation is to build a new facility. A new plant with new treatment methods such as ultrafiltration is most in line with Håbo municipality’s vision of decreasing chemical usage and sustainability, all while maintaining the water quality. Due to Håbo’s growing population and today’s water plants running close to maximum capacity, a new facility with a larger capacity should be considered.

Contaminants of emerging concern (CECs) are widespread in the water cycle. Their levels in disinfected waters are usually low, as they may transform into CEC disinfection byproducts (DBPs) during disinfection processes or partially removed in previous water treatment steps. The occurrence of CEC DBPs in real waters has been scarcely addressed, although their presence may be of relevance in water circular economy scenarios, and thus deserves further study in water regeneration systems. In this work, a database of CEC DBPs (n=1338) after chlorination was generated and is ready to use in future screening studies to assess the relevance of these chemicals in contaminat mixtures. Moreover, the transformation of CECs during chlorination, their main reaction pathways with chlorine, and current knowledge gaps were critically reviewed.

This work aims to apply and study a 3D radiative and fluid simulation by Computational Fluid Dynamics (CFD) in a UV Water treatment reactor, and understand the models and equations applied. The results are compared experimentally with a real reactor., Aquest treball te com a objectiu aplicar i estudiar una simulació radiativa i de fluids 3D mitjançant Computational Fluid Dynamics (CFD) a un reactor UV de tractament d'aigües, així com entendre els models i equacions que s'apliquen. Els resultats son comparats experimentalment amb un reactor real., Este trabajo tiene como objetivo aplicar y estudiar una simulación radiativa y de fluidos 3D mediante Computational Fluid Dynamics (CFD) a un reactor UV de tratamiento de aguas, así como entender los modelos y ecuaciones que se aplican. Los resultados son comparados experimentalmente con un reactor real.

Магістерська дисертація складається з: 84 ст., 16 рис., табл. 17. Зростаючі вимоги до якості питної спонукають до пошуку більш екологічно доцільних і ефективних методів її знезаражування й очищення. Мета даної роботи полягає в дослідженні знезаражуючої дії одержуваного із природного полімеру хітину хітозану (ХТЗ), у відношенні до E.coli і C.albicans у залежності від фізико-хімічних параметрів середовища. Встановлено, що ступінь інактивації культури E.coli не залежить від типу досліджених у роботі ХТЗ: високомолекулярного ХТЗ1 (молекулярна маса (Mw) 100–300 кДа) і низькомолекулярного ХТЗ2 (Mw 50-60 кДа) зі ступенем деацетилювання відповідно 95 і 75-85%. У випадку C.albicans високомолекулярний ХТЗ зі ступенем деацетилювання 95% є більш ефективним знезаражуючим агентом. Найбільш високий ступінь інактивації культури C.albicans ХТЗ1 досягається в слабко кислому середовищі (рН 5,0), тоді як при рН 8,5 знезаражуючий ефект є незначним. Вперше показано суттєвий внесок процесу флокуляції мікроорганізмів хітозаном у сумарний ефект знезаражування води. Показано, що наявність у воді домішок органічної й неорганічної природи зменшує як знезаражуючий, так і флокулюючий ефект полісахариду відносно мікробіологічного об'єкта, що зв'язано, мабуть, з конкуруючим впливом цих домішок на взаємодію молекул ХТЗ із мікроорганізмами. Отримані результати підтверджують, що C.albicans є більш надійним тест-об'єктом процесів знезаражування в порівнянні з E.coli, що має практичне значення., The master's thesis consists of 84 pages, 16 figures, 17 tables. Increasing demands on the drinking water quality require the search for more environmentally friendly and effective methods for its disinfection and purification. The purpose of this work was to study the disinfecting effect of chitosan (ChTS) obtained from a natural polymer in relation to E. coli and C. albicans, depending on the physicochemical parameters of the medium. It was established that the degree of inactivation of the E. coli culture does not depend on the type of ChTS studied in the work: high molecular weight ChTS1 (molecular weight (Mw) 100–300 kDa) and low molecular weight ChTS2 (Mw 50-60 kDa) with a deacetylation degree of 95 and 75-85%, respectively. In the case of C. albicans, high molecular weight ChTS1 with a degree of deacetylation of 95% is a more effective disinfecting agent. The highest degree of inactivation of C. albicans by ChTS1 is achieved in a slightly acidic environment (pH 5.0), while at pH 8.5 the disinfecting effect is negligible. For the first time, a significant contribution of the process of flocculation of microorganisms by chitosan to the total effect of water disinfection is shown. It was shown that the presence in water of impurities of an organic and inorganic nature reduces both the disinfecting and flocculating effect of the polysaccharide in relation to the microbiological objects, which is obviously associated with the competing effect of these impurities on the interaction of ChTS molecules with microorganisms. The results confirm that C. albicans is a more reliable test object of disinfection processes compared to E. coli, which is of practical importance., Магистерская диссертация состоит из 84 ст., 16 рис., табл. 17. Возрастающие требования к качеству питьевой воды требуют поиска более экологически целесообразных и эффективных методов ее обеззараживания и очистки. Цель настоящей работы состояла в исследовании обеззараживающего действия получаемого из природного полимера хитина хитозана (ХТЗ), в отношении E.coli и C.albicans в зависимости от физико-химических параметров среды. Установлено, что степень инактивации культуры E.coli не зависит от типа исследованных в работе ХТЗ: высокомолекулярного ХТЗ1 (молекулярная масса (Mw) 100–300 кДа) и низкомолекулярного ХТЗ2 (Mw 50-60 кДа) со степенью деацетиллирования соответственно 95 и 75-85%. В случае C.albicans высокомолекулярный ХТЗ со степенью деацетилирования 95% является более эффективным обеззараживающим агентом. Наиболее высокая степень инактивации культуры C.albicans ХТЗ1 достигается в слабо кислой среде (рН 5,0), тогда как при рН 8,5 обеззараживающий эффект является незначительным. Впервые показан существенный вклад процесса флокуляции микроорганизмов хитозаном в суммарный эффект обеззараживания воды. Показано, что наличие в воде примесей органической и неорганической природы уменьшает как обеззараживающий, так и флокулирующий эффект полисахарида в отношении микробиологического объекта, что связано, очевидно, с конкурирующим влиянием этих примесей на взаимодействие молекул ХТЗ с микроорганизмами. Полученные результаты подтверждают, что C.albicans является более надежным тест-объектом процессов обеззараживания по сравнению с E.coli, что имеет практическое значение.

Irrigation water can be a source of pathogenic contamination of fresh produce. Controlling the quality of the water used during primary production is important to ensure food safety and protect human health. Several measures to control the microbiological quality of irrigation water are available for growers, including preventative and mitigation strategies. However, clear guidance for growers on which strategies could be used to reduce microbiological contamination is needed. This study evaluates pathogenic microorganisms of concern in fresh produce and water, the microbiological criteria of water intended for agricultural purposes, and the preventative and mitigative microbial reduction strategies. This article provides suggestions for control measures that growers can take during primary production to reduce foodborne pathogenic contamination coming from irrigation water. Results show that controlling the water source, regime, and timing of irrigation may help to reduce the potential exposure of fresh produce to contamination. Moreover, mitigation strategies like electrolysis, ozone, UV, and photocatalysts hold promise either as a single treatment, with pretreatments that remove suspended material, or as combined treatments with another chemical or physical treatment(s). Based on the literature data, a decision tree was developed for growers, which describes preventative and mitigation strategies for irrigation-water disinfection based on the fecal coliform load of the irrigation water and the water turbidity. It helps guide growers when trying to evaluate possible control measures given the quality of the irrigation water available. Overall, the strategies available to control irrigation water used for fresh produce should be evaluated on a case-by-case basis because one strategy or technology does not apply to all scenarios.

El presente trabajo de grado tiene como objetivo la obtención de un agente desinfectante a partir de la electrólisis de cloruro de sodio para evaluar su aplicabilidad en agua potable, esto debido a que se evidencia la dificultad para llevar agua potable a zonas rurales especialmente ubicada en la zonas costeras del país, y la ausencia de mecanismos adecuados para adoptar un sistema integral que dé cobertura a toda la población, además de los riesgos que implica manipular y transportar los agentes desinfectantes más usados. El desarrollo del proyecto se realizó en tres fases: la primera fase fue la investigación de las variables involucradas en la técnica de electrólisis de cloruro de sodio, y a partir de la cual se determinaron las variables determinantes y las variables de control para desarrollar esta técnica; adicionalmente se especificaron las condiciones de operación a través de una matriz de referencias bibliográficas, lo cual permitió el planteamiento del diseño de experimentos en donde la concentración de sal, la densidad de corriente y la agitación son los tres factores y cada uno tiene tres niveles de operación.

El presente trabajo de grado tiene como objetivo la obtención de un agente desinfectante a partir de la electrólisis de cloruro de sodio para evaluar su aplicabilidad en agua potable, esto debido a que se evidencia la dificultad para llevar agua potable a zonas rurales especialmente ubicada en la zonas costeras del país, y la ausencia de mecanismos adecuados para adoptar un sistema integral que dé cobertura a toda la población, además de los riesgos que implica manipular y transportar los agentes desinfectantes más usados. El desarrollo del proyecto se realizó en tres fases: la primera fase fue la investigación de las variables involucradas en la técnica de electrólisis de cloruro de sodio, y a partir de la cual se determinaron las variables determinantes y las variables de control para desarrollar esta técnica; adicionalmente se especificaron las condiciones de operación a través de una matriz de referencias bibliográficas, lo cual permitió el planteamiento del diseño de experimentos en donde la concentración de sal, la densidad de corriente y la agitación son los tres factores y cada uno tiene tres niveles de operación.

Controlling water quality is critical in preventing cross-contamination during fresh produce washing. Process wash water (PWW) quality can be controlled by implementing chemical disinfection strategies. The aim of this study was to evaluate the pilot-scale efficacy of chlorine dioxide (ClO2) during processing on the reduction of Escherichia coli in the PWW and on processed fresh-cut ‘Lollo Rossa’ lettuce. The objective was to have a residual target concentration of either 5 or 3 mg/L ClO2 in the washing tank (3.5 m3) before and during 800 kg of lettuce processing (90 min). After 90 min., a nonpathogenic, non-Extended Spectrum Beta-Lactamase (ESBL) E. coli inoculum from an overnight culture broth (37 °C) was added to the tank resulting in an approximate final level of 106 CFU/mL. PWW and lettuce samples for microbiological and chemical analyses were taken before and after the input and supply halted. ClO2 concentrations quickly decreased after ClO2 input halted, yet a residual concentration of ≥2.5 mg/L and ≥2.1 mg/L ClO2, respectively for 5 and 3 mg/L pilots, was present 12 min after the supply halted. No detectable levels of E. coli (limit of detection 5 log) were determined in the water within 1 min after E. coli was added to the ClO2 containing wash water. Results demonstrated that ClO2 use at the semi-commercial pilot scale was able to reduce the E. coli peak contamination in the PWW. After storage (5 days, 4 °C), background microbial communities (i.e., fluorescent Pseudomonads and total heterotrophic bacteria) grew out on lettuce. Overall, ClO2 decreased the potential for cross-contamination between batches compared to when no sanitizer was used. Chlorate levels of the lettuce sampled before entering the wash water ranged from 7.3–11.6 μg/kg. The chlorate levels of the lettuce sampled after being washed in the ClO2 containing wash water, as well as after rinsing and centrifugation, ranged from 22.8–60.4 μg/kg; chlorite levels ranged from 1.3–1.6 mg/kg, while pe

Silver nanoparticle (Ag NP)-containing biopolymer nanocomposites possess antibacterial activity which is largely associated with the NP size, shape, surface area and medium. These biomaterials have been investigated as dressing for wounds and burns, treatment for infected areas, coatings for orthopaedic and dental implants and for water disinfection. This broad-acting and potent antibacterial activity are likely due to a multifaceted mechanism of action that is not completely understood. Although the Ag NPs are useful against antibiotic-resistant bacteria, their level of toxicity is not well established and requires further investigation. This review details the brief perspective, critical analysis of the currently available articles and discusses on the future applications of these potentially life-saving nanocomposites.

El presente trabajo de grado tiene como objetivo la obtención de un agente desinfectante a partir de la electrólisis de cloruro de sodio para evaluar su aplicabilidad en agua potable, esto debido a que se evidencia la dificultad para llevar agua potable a zonas rurales especialmente ubicada en la zonas costeras del país, y la ausencia de mecanismos adecuados para adoptar un sistema integral que dé cobertura a toda la población, además de los riesgos que implica manipular y transportar los agentes desinfectantes más usados. El desarrollo del proyecto se realizó en tres fases: la primera fase fue la investigación de las variables involucradas en la técnica de electrólisis de cloruro de sodio, y a partir de la cual se determinaron las variables determinantes y las variables de control para desarrollar esta técnica; adicionalmente se especificaron las condiciones de operación a través de una matriz de referencias bibliográficas, lo cual permitió el planteamiento del diseño de experimentos en donde la concentración de sal, la densidad de corriente y la agitación son los tres factores y cada uno tiene tres niveles de operación.

The aim of this study was to investigate the effects of dibromoacetonitrile (DBAN), a by-product in water bacterial control, at sublethal concentrations on rat thymocytes, by using a cytometric technique with appropriate fluorescent dyes. By using this method, the possibility that DBAN induces cellular actions related to oxidative stress was assessed. DBAN reduced the content of cellular nonprotein thiols under Zn2+-free conditions. It elevated the intracellular level of Zn2+, being independent from external Zn2+. DBAN increased cell vulnerability to the cytotoxic action of hydrogen peroxide. These actions of DBAN were likely related to oxidative stress. DBAN is formed by the reaction of bromides and chlorinated oxidants during water disinfection. Hydrolysis of 2,2-dibromo-3-nitrilopropionamide, an antimicrobial used in hydraulic fracturing fluids for production of shale gas and oil, produces DBAN. Therefore, the concern regarding the levels of DBAN in industrial water systems is necessary to avoid the environmental risk to humans and wild mammals.

El presente trabajo de grado tiene como objetivo la obtención de un agente desinfectante a partir de la electrólisis de cloruro de sodio para evaluar su aplicabilidad en agua potable, esto debido a que se evidencia la dificultad para llevar agua potable a zonas rurales especialmente ubicada en la zonas costeras del país, y la ausencia de mecanismos adecuados para adoptar un sistema integral que dé cobertura a toda la población, además de los riesgos que implica manipular y transportar los agentes desinfectantes más usados. El desarrollo del proyecto se realizó en tres fases: la primera fase fue la investigación de las variables involucradas en la técnica de electrólisis de cloruro de sodio, y a partir de la cual se determinaron las variables determinantes y las variables de control para desarrollar esta técnica; adicionalmente se especificaron las condiciones de operación a través de una matriz de referencias bibliográficas, lo cual permitió el planteamiento del diseño de experimentos en donde la concentración de sal, la densidad de corriente y la agitación son los tres factores y cada uno tiene tres niveles de operación.

El presente trabajo de grado tiene como objetivo la obtención de un agente desinfectante a partir de la electrólisis de cloruro de sodio para evaluar su aplicabilidad en agua potable, esto debido a que se evidencia la dificultad para llevar agua potable a zonas rurales especialmente ubicada en la zonas costeras del país, y la ausencia de mecanismos adecuados para adoptar un sistema integral que dé cobertura a toda la población, además de los riesgos que implica manipular y transportar los agentes desinfectantes más usados. El desarrollo del proyecto se realizó en tres fases: la primera fase fue la investigación de las variables involucradas en la técnica de electrólisis de cloruro de sodio, y a partir de la cual se determinaron las variables determinantes y las variables de control para desarrollar esta técnica; adicionalmente se especificaron las condiciones de operación a través de una matriz de referencias bibliográficas, lo cual permitió el planteamiento del diseño de experimentos en donde la concentración de sal, la densidad de corriente y la agitación son los tres factores y cada uno tiene tres niveles de operación.

El presente trabajo de grado tiene como objetivo la obtención de un agente desinfectante a partir de la electrólisis de cloruro de sodio para evaluar su aplicabilidad en agua potable, esto debido a que se evidencia la dificultad para llevar agua potable a zonas rurales especialmente ubicada en la zonas costeras del país, y la ausencia de mecanismos adecuados para adoptar un sistema integral que dé cobertura a toda la población, además de los riesgos que implica manipular y transportar los agentes desinfectantes más usados. El desarrollo del proyecto se realizó en tres fases: la primera fase fue la investigación de las variables involucradas en la técnica de electrólisis de cloruro de sodio, y a partir de la cual se determinaron las variables determinantes y las variables de control para desarrollar esta técnica; adicionalmente se especificaron las condiciones de operación a través de una matriz de referencias bibliográficas, lo cual permitió el planteamiento del diseño de experimentos en donde la concentración de sal, la densidad de corriente y la agitación son los tres factores y cada uno tiene tres niveles de operación.

El presente trabajo de grado tiene como objetivo la obtención de un agente desinfectante a partir de la electrólisis de cloruro de sodio para evaluar su aplicabilidad en agua potable, esto debido a que se evidencia la dificultad para llevar agua potable a zonas rurales especialmente ubicada en la zonas costeras del país, y la ausencia de mecanismos adecuados para adoptar un sistema integral que dé cobertura a toda la población, además de los riesgos que implica manipular y transportar los agentes desinfectantes más usados. El desarrollo del proyecto se realizó en tres fases: la primera fase fue la investigación de las variables involucradas en la técnica de electrólisis de cloruro de sodio, y a partir de la cual se determinaron las variables determinantes y las variables de control para desarrollar esta técnica; adicionalmente se especificaron las condiciones de operación a través de una matriz de referencias bibliográficas, lo cual permitió el planteamiento del diseño de experimentos en donde la concentración de sal, la densidad de corriente y la agitación son los tres factores y cada uno tiene tres niveles de operación.

El agua es una fuente vital para la vida del ser humano y su consumo no solamente es importante sino necesario, pero al mismo tiempo es un excelente medio para que en ella se desarrollen y reproduzcan bacterias patógenas y especialmente la Escherichia coli más conocida como E.coli, causante de enfermedades gastrointestinales que se presentan sobre todo en niños menores de 5 años a causa de la ingesta de agua contaminada por lo cual se requiere de su potabilización y que se pueda consumir sin que exista riesgo alguno para la salud de las personas. La desinfección del agua puede realizarse mediante procesos físicos o químicos que permiten la eliminación de agentes contaminantes. Los métodos más utilizados son los químicos tales como la cloración y la ozonización, y los métodos físicos como la radiación ultravioleta en menor escala. Los procedimientos mediante la utilización de elementos químicos, si bien cumplen con el objetivo, en muchas de las veces tienen efectos secundarios en las personas, es por eso que se busca la utilización de procesos que a la vez que logren desinfectar el agua, no presenten efectos secundarios y es por ello que se prueba con la utilización de luz infrarroja que no se le conocen efectos adversos en el ser humano, pero que tampoco se tiene mucho conocimiento sobre los efectos inhibidores de la presencia patógenos en el agua. El desarrollo del presente trabajo permitirá que en un primer capítulo se haga un acercamiento a las generalidades del agua, de los métodos y procesos de desinfección existentes a los cuales es sometida; el conocimiento de la bacteria E.coli, al igual que las generalidades de la luz láser y sus aplicaciones.

El agua es una fuente vital para la vida del ser humano y su consumo no solamente es importante sino necesario, pero al mismo tiempo es un excelente medio para que en ella se desarrollen y reproduzcan bacterias patógenas y especialmente la Escherichia coli más conocida como E.coli, causante de enfermedades gastrointestinales que se presentan sobre todo en niños menores de 5 años a causa de la ingesta de agua contaminada por lo cual se requiere de su potabilización y que se pueda consumir sin que exista riesgo alguno para la salud de las personas. La desinfección del agua puede realizarse mediante procesos físicos o químicos que permiten la eliminación de agentes contaminantes. Los métodos más utilizados son los químicos tales como la cloración y la ozonización, y los métodos físicos como la radiación ultravioleta en menor escala. Los procedimientos mediante la utilización de elementos químicos, si bien cumplen con el objetivo, en muchas de las veces tienen efectos secundarios en las personas, es por eso que se busca la utilización de procesos que a la vez que logren desinfectar el agua, no presenten efectos secundarios y es por ello que se prueba con la utilización de luz infrarroja que no se le conocen efectos adversos en el ser humano, pero que tampoco se tiene mucho conocimiento sobre los efectos inhibidores de la presencia patógenos en el agua. El desarrollo del presente trabajo permitirá que en un primer capítulo se haga un acercamiento a las generalidades del agua, de los métodos y procesos de desinfección existentes a los cuales es sometida; el conocimiento de la bacteria E.coli, al igual que las generalidades de la luz láser y sus aplicaciones.

This study introduces natural occurring magnetic pyrrhotite (NP) as an environmentally friendly, easy available, and cost-effective alternative catalyst to activate persulfate (PS) of controlling microbial water contaminants. The E. coli K-12 inactivation kinetics observed in batch experiments was well described with first-order reaction. The optimum inactivation rate (k = 0.47 log/min) attained at a NP dose of 1 g/L and a PS dose of 1 mM, corresponding to total inactivation of 7 log10 cfu/mL cells within 15 min. Measured k increased > 2-fold when temperature increased from 20 to 50 °C; and > 4-fold when pH decreased from 9 to 3. Aerobic conditions were more beneficial to cell inactivation than anaerobic conditions due to more reactive oxygen species (ROS) generated. ROS responsible for the inactivation were identified to be [rad]SO4 − > [rad]OH > H2O2 based on a positive scavenging test and in situ ROS determination. In situ characterization suggested that PS effectively bind to NP surface was likely to form charge transfer complex (≡Fe(II)⋯O3SO[sbnd]OSO3 -), which mediated ROS generation and E. coli K-12 oxidation. The increased cell-envelope lesions consequently aggravated intracellular protein depletion and genome damage to cause definite bacterial death. The NP still maintained good physiochemical structure and stable activity even after 4 cycle. Moreover, NP/PS system also exhibited good E. coli K-12 inactivation efficiency in authentic water matrices like surface water and effluents of secondary wastewater. © 2017 Elsevier Ltd

El agua es una fuente vital para la vida del ser humano y su consumo no solamente es importante sino necesario, pero al mismo tiempo es un excelente medio para que en ella se desarrollen y reproduzcan bacterias patógenas y especialmente la Escherichia coli más conocida como E.coli, causante de enfermedades gastrointestinales que se presentan sobre todo en niños menores de 5 años a causa de la ingesta de agua contaminada por lo cual se requiere de su potabilización y que se pueda consumir sin que exista riesgo alguno para la salud de las personas. La desinfección del agua puede realizarse mediante procesos físicos o químicos que permiten la eliminación de agentes contaminantes. Los métodos más utilizados son los químicos tales como la cloración y la ozonización, y los métodos físicos como la radiación ultravioleta en menor escala. Los procedimientos mediante la utilización de elementos químicos, si bien cumplen con el objetivo, en muchas de las veces tienen efectos secundarios en las personas, es por eso que se busca la utilización de procesos que a la vez que logren desinfectar el agua, no presenten efectos secundarios y es por ello que se prueba con la utilización de luz infrarroja que no se le conocen efectos adversos en el ser humano, pero que tampoco se tiene mucho conocimiento sobre los efectos inhibidores de la presencia patógenos en el agua. El desarrollo del presente trabajo permitirá que en un primer capítulo se haga un acercamiento a las generalidades del agua, de los métodos y procesos de desinfección existentes a los cuales es sometida; el conocimiento de la bacteria E.coli, al igual que las generalidades de la luz láser y sus aplicaciones.

El agua es una fuente vital para la vida del ser humano y su consumo no solamente es importante sino necesario, pero al mismo tiempo es un excelente medio para que en ella se desarrollen y reproduzcan bacterias patógenas y especialmente la Escherichia coli más conocida como E.coli, causante de enfermedades gastrointestinales que se presentan sobre todo en niños menores de 5 años a causa de la ingesta de agua contaminada por lo cual se requiere de su potabilización y que se pueda consumir sin que exista riesgo alguno para la salud de las personas. La desinfección del agua puede realizarse mediante procesos físicos o químicos que permiten la eliminación de agentes contaminantes. Los métodos más utilizados son los químicos tales como la cloración y la ozonización, y los métodos físicos como la radiación ultravioleta en menor escala. Los procedimientos mediante la utilización de elementos químicos, si bien cumplen con el objetivo, en muchas de las veces tienen efectos secundarios en las personas, es por eso que se busca la utilización de procesos que a la vez que logren desinfectar el agua, no presenten efectos secundarios y es por ello que se prueba con la utilización de luz infrarroja que no se le conocen efectos adversos en el ser humano, pero que tampoco se tiene mucho conocimiento sobre los efectos inhibidores de la presencia patógenos en el agua. El desarrollo del presente trabajo permitirá que en un primer capítulo se haga un acercamiento a las generalidades del agua, de los métodos y procesos de desinfección existentes a los cuales es sometida; el conocimiento de la bacteria E.coli, al igual que las generalidades de la luz láser y sus aplicaciones.

This study introduces natural occurring magnetic pyrrhotite (NP) as an environmentally friendly, easy available, and cost-effective alternative catalyst to activate persulfate (PS) of controlling microbial water contaminants. The E. coli K-12 inactivation kinetics observed in batch experiments was well described with first-order reaction. The optimum inactivation rate (k = 0.47 log/min) attained at a NP dose of 1 g/L and a PS dose of 1 mM, corresponding to total inactivation of 7 log10 cfu/mL cells within 15 min. Measured k increased > 2-fold when temperature increased from 20 to 50 °C; and > 4-fold when pH decreased from 9 to 3. Aerobic conditions were more beneficial to cell inactivation than anaerobic conditions due to more reactive oxygen species (ROS) generated. ROS responsible for the inactivation were identified to be [rad]SO4 − > [rad]OH > H2O2 based on a positive scavenging test and in situ ROS determination. In situ characterization suggested that PS effectively bind to NP surface was likely to form charge transfer complex (≡Fe(II)⋯O3SO[sbnd]OSO3 -), which mediated ROS generation and E. coli K-12 oxidation. The increased cell-envelope lesions consequently aggravated intracellular protein depletion and genome damage to cause definite bacterial death. The NP still maintained good physiochemical structure and stable activity even after 4 cycle. Moreover, NP/PS system also exhibited good E. coli K-12 inactivation efficiency in authentic water matrices like surface water and effluents of secondary wastewater. © 2017 Elsevier Ltd

Washing fresh produce with potable water helps to remove microorganisms, providing about a 1- to 2-log reduction, but this process can also pose an opportunity for cross-contamination of bacteria in the washing tank. The objective of this study was to evaluate the efficacy of three chemical sanitizers, sodium hypochlorite, chlorine dioxide, and a silver-copper solution on the reduction of S. Typhimurium and extended-spectrum beta-lactamase (ESBL) E. coli as well as to evaluate the impact bacterial cell history and water quality had on sanitizer efficacy. This was investigated with three scenarios representing different contamination routes and history of cells: (i) on starved and non-starved cells in potable water, (ii) on starved and non-starved cells in lettuce wash water and on lettuce leaf punches, and (iii) on non-starved cells in organically loaded process wash water (PWW). Sodium hypochlorite (NaClO) and chlorine dioxide (ClO2) were more effective in preventing cross-contamination in the potable water than the silver-copper solution. Starved and non-starved bacterial cells displayed minor differences in their susceptibility to sanitizing agents in the (i) potable water and (ii) lettuce wash water demonstrating that other conditions greater influenced sanitizer efficacy. Particularly, the organic load of the water, wash water temperature, and pathogen attachment and release from the produce were shown to affect a sanitizer's efficacy during washing. Furthermore, results emphasize that chemical sanitizer use should focus more on wash water disinfection, rather than produce decontamination, to prevent pathogenic cross-contamination during processing. Future research should investigate the feasibility of ClO2 application during pilot-scale processing.

We investigated the effect of ultraviolet germicidal irradiation (UVI) from a low-pressure mercury lamp on several pathogenic Aspergillus spp. including A. flavipes, A. flavus, A. fumigatus, A. glaucus, A. nidulans, A. niger, A. terreus, A. ustus and A. versicolor suspended in tap water under laboratory-scale conditions. It was shown that within 10 s of exposure, time species such as A. glaucus, A. niudulans and A. ustus were completely inactivated, while 40 s were needed for the elimination of all the species tested. A. flavus and A. niger were found to be less susceptible than other species. Based on these results we conclude that UV disinfection could effectively inactivate Aspergillus spp. in tap water. Such disinfection could be used to reduce potential exposure of high-risk patients to fungal aerosols, particularly in hospital settings, where point-of-use (POU) UV light devices could be installed to provide safe water at a very low cost.

We investigated the effect of ultraviolet germicidal irradiation (UVI) from a low-pressure mercury lamp on several pathogenic Aspergillus spp. including A. flavipes, A. flavus, A. fumigatus, A. glaucus, A. nidulans, A. niger, A. terreus, A. ustus and A. versicolor suspended in tap water under laboratory-scale conditions. It was shown that within 10 s of exposure, time species such as A. glaucus, A. niudulans and A. ustus were completely inactivated, while 40 s were needed for the elimination of all the species tested. A. flavus and A. niger were found to be less susceptible than other species. Based on these results we conclude that UV disinfection could effectively inactivate Aspergillus spp. in tap water. Such disinfection could be used to reduce potential exposure of high-risk patients to fungal aerosols, particularly in hospital settings, where point-of-use (POU) UV light devices could be installed to provide safe water at a very low cost.

El agua es una fuente vital para la vida del ser humano y su consumo no solamente es importante sino necesario, pero al mismo tiempo es un excelente medio para que en ella se desarrollen y reproduzcan bacterias patógenas y especialmente la Escherichia coli más conocida como E.coli, causante de enfermedades gastrointestinales que se presentan sobre todo en niños menores de 5 años a causa de la ingesta de agua contaminada por lo cual se requiere de su potabilización y que se pueda consumir sin que exista riesgo alguno para la salud de las personas. La desinfección del agua puede realizarse mediante procesos físicos o químicos que permiten la eliminación de agentes contaminantes. Los métodos más utilizados son los químicos tales como la cloración y la ozonización, y los métodos físicos como la radiación ultravioleta en menor escala. Los procedimientos mediante la utilización de elementos químicos, si bien cumplen con el objetivo, en muchas de las veces tienen efectos secundarios en las personas, es por eso que se busca la utilización de procesos que a la vez que logren desinfectar el agua, no presenten efectos secundarios y es por ello que se prueba con la utilización de luz infrarroja que no se le conocen efectos adversos en el ser humano, pero que tampoco se tiene mucho conocimiento sobre los efectos inhibidores de la presencia patógenos en el agua. El desarrollo del presente trabajo permitirá que en un primer capítulo se haga un acercamiento a las generalidades del agua, de los métodos y procesos de desinfección existentes a los cuales es sometida; el conocimiento de la bacteria E.coli, al igual que las generalidades de la luz láser y sus aplicaciones.

El agua es una fuente vital para la vida del ser humano y su consumo no solamente es importante sino necesario, pero al mismo tiempo es un excelente medio para que en ella se desarrollen y reproduzcan bacterias patógenas y especialmente la Escherichia coli más conocida como E.coli, causante de enfermedades gastrointestinales que se presentan sobre todo en niños menores de 5 años a causa de la ingesta de agua contaminada por lo cual se requiere de su potabilización y que se pueda consumir sin que exista riesgo alguno para la salud de las personas. La desinfección del agua puede realizarse mediante procesos físicos o químicos que permiten la eliminación de agentes contaminantes. Los métodos más utilizados son los químicos tales como la cloración y la ozonización, y los métodos físicos como la radiación ultravioleta en menor escala. Los procedimientos mediante la utilización de elementos químicos, si bien cumplen con el objetivo, en muchas de las veces tienen efectos secundarios en las personas, es por eso que se busca la utilización de procesos que a la vez que logren desinfectar el agua, no presenten efectos secundarios y es por ello que se prueba con la utilización de luz infrarroja que no se le conocen efectos adversos en el ser humano, pero que tampoco se tiene mucho conocimiento sobre los efectos inhibidores de la presencia patógenos en el agua. El desarrollo del presente trabajo permitirá que en un primer capítulo se haga un acercamiento a las generalidades del agua, de los métodos y procesos de desinfección existentes a los cuales es sometida; el conocimiento de la bacteria E.coli, al igual que las generalidades de la luz láser y sus aplicaciones.

Навчальний посібник має за мету ознайомити студентів спеціальності «Екологія та охорона навколишнього середовища» з загальними принципами екологічної безпеки гідросфери. Для аграрних закладів освіти по курсам «Загальна гідрологія» та «Водопостачання, водовідвід і поліпшення якості води»., Учебное пособие имеет цель ознакомить студентов специальности «Экология и охрана окружающей среды» с общими принципами экологической безопасности гидросферы. Для аграрных высших учебных заведений по курсам «Общая гидрология» и «Водоснабжение, водоотвод и улучшения качества виды»., It contains a list of definitions and concepts that have the aim to acquaint students of specialty «Ecology and Environment» with the general principles of environmental safety hydrosphere. For agricultural higher education courses on «General hydrology» and «Water supply, drainage and better species».

Навчальний посібник має за мету ознайомити студентів спеціальності «Екологія та охорона навколишнього середовища» з загальними принципами екологічної безпеки гідросфери. Для аграрних закладів освіти по курсам «Загальна гідрологія» та «Водопостачання, водовідвід і поліпшення якості води»., Учебное пособие имеет цель ознакомить студентов специальности «Экология и охрана окружающей среды» с общими принципами экологической безопасности гидросферы. Для аграрных высших учебных заведений по курсам «Общая гидрология» и «Водоснабжение, водоотвод и улучшения качества виды»., It contains a list of definitions and concepts that have the aim to acquaint students of specialty «Ecology and Environment» with the general principles of environmental safety hydrosphere. For agricultural higher education courses on «General hydrology» and «Water supply, drainage and better species».

Навчальний посібник має за мету ознайомити студентів спеціальності «Екологія та охорона навколишнього середовища» з загальними принципами екологічної безпеки гідросфери. Для аграрних закладів освіти по курсам «Загальна гідрологія» та «Водопостачання, водовідвід і поліпшення якості води»., Учебное пособие имеет цель ознакомить студентов специальности «Экология и охрана окружающей среды» с общими принципами экологической безопасности гидросферы. Для аграрных высших учебных заведений по курсам «Общая гидрология» и «Водоснабжение, водоотвод и улучшения качества виды»., It contains a list of definitions and concepts that have the aim to acquaint students of specialty «Ecology and Environment» with the general principles of environmental safety hydrosphere. For agricultural higher education courses on «General hydrology» and «Water supply, drainage and better species».

В работе приведен сравнительный анализ инактивации микроорганизмов с использованием хлорсодержащих дезинфицирующих растворов и раствора озона в воде в сравнимых условиях. В качестве исследуемых хлорсодержащих веществ использовались хлорная известь, гипохлорит натрия и кальция. В качестве тест-организмов для определения эффективности дезинфекции использовались бактерии: Clostridium sp.; Pseudomonas fluorescens; Escherichia coli.

Nanomaterials open an alternative way for water disinfection. However, limitations such as aggregation, toxicity, and complex post-treatment block their practical application. In this study, an antibacterial silver/reduced graphene oxide (Ag/rGO) hydrogel consisting of controlled porous rGO network and well-dispersed Ag nanoparticle is synthesized by a facile hydrothermal reaction. Scanning electron microscopy, transmission electron microscope, X-ray diffraction, mercury porosimetry, and Fourier transform IR spectroscopy are employed to characterize the Ag/rGO hydrogel. The 3D structure of the rGO network serves as an excellent support for Ag nanoparticles. Disinfection experiments show that the Ag/rGO hydrogel exhibits good efficacy against Escherichia coli when used as a bactericidal filter driven by gravity. The mechanistic study indicates that bacteria cells are inactivated due to cell membrane damage induced by silver nanoparticles and rGO nanosheets when they flow through Ag/rGO hydrogel. Moreover, due to the retaining of Ag by rGO, the leaching level of silver from Ag/rGO hydrogel is considerably lower than the drinking water standard. This study sheds new light on designing antibacterial materials for point-of-use water disinfection application.

The potential cross-contamination of pathogens between clean and contaminated produce in the washing tank is highly dependent on the water quality. Process wash water disinfectants are applied to maintain the water quality during processing. The review examines the efficacy of process wash water disinfectants during produce processing with the aim to prevent cross-contamination of pathogens. Process wash water disinfection requires short contact times so microorganisms are rapidly inactivated. Free chlorine, chlorine dioxide, ozone, and peracetic acid were considered suitable disinfectants. A disinfectant’s reactivity with the organic matter will determine the disinfectant residual, which is of paramount importance for microbial inactivation and should be monitored in situ. Furthermore, the chemical and worker safety, and the legislative framework will determine the suitability of a disinfection technique. Current research often focuses on produce decontamination and to a lesser extent on preventing cross-contamination. Further research on a sanitizer’s efficacy in the washing water is recommended at the laboratory scale, in particular with experimental designs reflecting industrial conditions. Validation on the industrial scale is warranted to better understand the overall effects of a sanitizer.

This study evaluates the effectiveness of solar water disinfection (SODIS) in the reduction and inactivation of hepatitis A virus (HAV) and of the human Norovirus surrogate, murine Norovirus (MNV-1), under natural solar conditions. Experiments were performed in 330 ml polyethylene terephthalate (PET) bottles containing HAV or MNV-1 contaminated waters (103 PFU/ml) that were exposed to natural sunlight for 2 to 8 h. Parallel experiments under controlled temperature and/or in darkness conditions were also included. Samples were concentrated by electropositive charged filters and analysed by RT-real time PCR (RT-qPCR) and infectivity assays. Temperature reached in bottles throughout the exposure period ranged from 22 to 40ºC. After 8 h of solar exposure (cumulative UV dose of ~828 kJ/m2 and UV irradiance of ~20 kJ/l), the results showed significant (P < 0.05) reductions from 4.0 (±0.56) ×104 to 3.15 (±0.69) × 103 RNA copies/100 ml (92.1%, 1.1 log) for HAV and from 5.91 (±0.59) × 104 to 9.24 (±3.91) × 103 RNA copies/100 ml (84.4%, 0.81 log) for MNV-1. SODIS conditions induced a loss of infectivity between 33.4% and 83.4% after 4 to 8 h in HAV trials, and between 33.4% and 66.7% after 6 h to 8 h in MNV-1 trials. The results obtained indicated a greater importance of sunlight radiation over the temperature as the main factor for viral reduction. [Int Microbiol 2015; 18(1):41-49]Keywords: Solar water disinfection (SODIS) · water disinfection · hepatitis A virus (HAV) · murine Norovirus (MNV-1)

This study describes the relationship between physical activity and intake of trihalomethanes (THMs), namely chloroform (CHCl3), bromodichloromethane (CHCl2Br), dibromochloromethane (CHClBr2) and bromoform (CHBr3), in individuals exposed in two indoor swimming pools which used different disinfection agents, chlorine (Cl-SP) and bromine (Br-SP). CHCl3 and CHBr3 were the dominant compounds in air and water of the Cl-SP and Br-SP, respectively. Physical exercise was assessed from distance swum and energy expenditure. The changes in exhaled breath concentrations of these compounds were measured from the differences after and before physical activity.A clear dependence between distance swum or energy expenditure and exhaled breath THM concentrations was observed. The statistically significant relationships involved higher THM concentrations at higher distances swum. However, air concentration was the major factor determining the CHCl3 and CHCl2Br intake in swimmers whereas distance swum was the main factor for CHBr3 intake. These two causes of THM incorporation into swimmers concurrently intensify the concentrations of these compounds into exhaled breath and pointed to inhalation as primary mechanism for THM uptake. Furthermore, the rates of THM incorporation were proportionally higher as higher was the degree of bromination of the THM species. This trend suggested that air-water partition mechanisms in the pulmonary system determined higher retention of the THM compounds with lower Henry's Law volatility constants than those of higher constant values. Inhalation is therefore the primary mechanisms for THM exposure of swimmers in indoor buildings. © 2015 Elsevier Inc.

This study evaluates the effectiveness of solar water disinfection (SODIS) in the reduction and inactivation of hepatitis A virus (HAV) and of the human Norovirus surrogate, murine Norovirus (MNV-1), under natural solar conditions. Experiments were performed in 330 ml polyethylene terephthalate (PET) bottles containing HAV or MNV-1 contaminated waters (103 PFU/ml) that were exposed to natural sunlight for 2 to 8 h. Parallel experiments under controlled temperature and/or in darkness conditions were also included. Samples were concentrated by electropositive charged filters and analysed by RT-real time PCR (RT-qPCR) and infectivity assays. Temperature reached in bottles throughout the exposure period ranged from 22 to 40ºC. After 8 h of solar exposure (cumulative UV dose of ~828 kJ/m2 and UV irradiance of ~20 kJ/l), the results showed significant (P < 0.05) reductions from 4.0 (±0.56) ×104 to 3.15 (±0.69) × 103 RNA copies/100 ml (92.1%, 1.1 log) for HAV and from 5.91 (±0.59) × 104 to 9.24 (±3.91) × 103 RNA copies/100 ml (84.4%, 0.81 log) for MNV-1. SODIS conditions induced a loss of infectivity between 33.4% and 83.4% after 4 to 8 h in HAV trials, and between 33.4% and 66.7% after 6 h to 8 h in MNV-1 trials. The results obtained indicated a greater importance of sunlight radiation over the temperature as the main factor for viral reduction. [Int Microbiol 2015; 18(1):41-49]Keywords: Solar water disinfection (SODIS) · water disinfection · hepatitis A virus (HAV) · murine Norovirus (MNV-1)