Solar Disinfection Research Articles

Visible-Light-Induced Rapid Elimination of Antibiotic Resistance Contaminations Using Graphitic Carbon Nitride Tailored with Carrier Confinement Domains.

Solar water disinfection facilitated by photocatalyst has been considered a viable point-of-use (POU) method for mitigating antibiotic resistance contaminations at the household or community levels. Here, density functional theory calculations are used to guide the fabrication of a carrier confinement domains (CCD)-decorated graphitic carbon nitride (CN) photocatalyst. The CCD integration effectively disrupts the electron distribution symmetry of CN, amplifies its local electron density, and facilitates the formation of long-range ordered structure, thereby enhancing charge separation efficiency. Importantly, the CCD directs the migration of photogenerated carriers to specific regions upon light illumination, effectively minimizing their spatial proximity. As a result, the overall reactive oxygen species level of the photocatalytic system is markedly elevated, with a twelvefold increase in H2O2 concentration, alongside a nearly two-order-of-magnitude rise in •O2 - and •OH steady-state concentrations. Remarkably, a record-high disinfection efficiency is attained, successfully inactivating 7 log of antibiotic-resistant bacteria within 30min. Additionally, the photocatalyst can be integrated into a continuous-flow fixed-bed reactor, facilitating clean water production for up to 60h at a rate of 121Lm-2day-1, highlighting its significant potential for POU applications.

Global transcriptional response of Pseudomonas aeruginosa to UVA radiation.

Ultraviolet A (UVA) radiation is the major fraction of UV radiation reaching the Earth's surface. Its harmful effects on microorganisms, due mainly to oxidative damage, have been exploited for development of natural solar and commercial UVA-based disinfection methods. In this work, the global transcriptional response of Pseudomonas aeruginosa exposed to ultraviolet A (UVA) radiation was analyzed. To conduct this study, we analyzed the whole transcriptome of the PAO1 strain grown to logarithmic phase under sublethal doses of UVA or in the dark. We found that a total of 298 genes responded to UVA with a change of at least two-fold (5.36% of the total P. aeruginosa genome), and showed equal amount of induced and repressed genes. An important fraction of the induced genes were involved in the response to DNA damage and included induction of SOS, prophage and pyocins genes. The results presented in this study suggest that one of the main UVA targets are proteins carrying [Fe-S] clusters since several genes involved in the processes of synthesis, trafficking and assembly of these structures were upregulated. The management of intracellular iron levels also seems to be a robust response to this stress factor. The strong induction of genes involved in denitrification suggest that this pathway and/or reactive nitrogen species such as nitric oxide could have a role in the response to this radiation. Regarding the down-regulated genes, we found many involved in the biosynthesis of PQS, a quorum-sensing signal molecule with a possible role as endogenous photosensitizer.

Priority areas for the use of solar water disinfection (SODIS) in Brazil: a spatial approach

ABSTRACT This paper presents a methodology for the development of a potential and priority use map for the application of the solar water disinfection (SODIS) method in Brazil. The assessment of solar radiation was conducted, with a particular focus on the annual average global horizontal irradiance (GHI). The water vulnerability index (WVI) and the economic-social-ecosystemic (ESE)-WVI were developed and employed as indicators to define the priority regions for the application of SODIS. The combination of the GHI and WVI maps yielded a SODIS usage potential index (SUPI). The combination of the SUPI map with information pertaining to the human, economic, and ecosystem dimensions of water vulnerability (ESE-WVI) yielded the SODIS usage priority index. The analysis revealed that the country exhibits favorable levels of solar radiation, making the implementation of SODIS a viable option, particularly in the Northeast region. Furthermore, the study identified regions with greater water vulnerability, such as the semi-arid region and some parts of the Amazon, as priorities for the application of SODIS. In conclusion, SODIS represents a viable water treatment technique for various regions in Brazil, particularly those with abundant solar radiation and concerns regarding water security.

The use of a solar simulator device to standardize microbiological decontamination of contaminated water by solar disinfection by the SODIS and MB/SODIS protocols

AbstractConsuming microbiologically‐contaminated water is the primary cause of many water‐borne diseases and deaths worldwide. Governments aim at providing drinking water for vulnerable populations, especially through low‐cost interventions. Therefore, the solar disinfection (SODIS) of such pathogens provides a simple and cost‐effective way to obtain good quality water. In this procedure, PET bottles are filled with contaminated water and exposed to sunlight for 1–2 days. To accelerate decontamination, methylene blue (MB) dye added as a photocatalyst, boosts singlet oxygen generation upon absorbing red‐band sunlight. This study explores the use of a Sunlight Simulator (SSL) device to research and standardize the SODIS method with a vital dye as MB. PET bottles were filled with artificially‐contaminated water with Streptococcus epidermidis and Deinococcus radiodurans Gram‐positive bacteria, Escherichia coli and Salmonella typhimurium Gram‐negative bacteria, or bacteriophage λ as well. In all experiments, 50 ng/mL MB ensued a synergistic lethal effect after SSL exposure. The results indicate that bacterial and bacteriophage inactivation can be achieved in shorter times with MB‐SSL treatment compared to SSL without MB. In this sense, when compared to previous sunlight‐SODIS results, the SSL source is a reliable tool to study the parameters of both SODIS and MB‐SODIS protocols, and also a feasible tool to afford assays whenever there are unfavorable climate conditions.

A espiritualidade de Francisco de Sales e o acompanhamento espiritual

The present study presents the contributions of Francis de Sales on the theme of spiritual accompaniment. The work is developed from the concept of spiritual accompaniment as friendship, understanding it as a practice that respects the autonomy of the accompanied subject. It follows from this, then, that the vision of the human being must be integral, in the sense that there is a concern with the intellectual, human and spiritual aspect. The path that seems most appropriate and that is followed for this analysis is thematic. This work will make it possible to situate the Salesian practice of spiritual accompaniment as a service to the human person. At the same time, it is hoped to make explicit that Salesian spirituality is an experience open to all, experiencing the "God of the human heart."

Intercalation of V2O5 and Polypyrrole into a Graphene Oxide Layer: A Hybrid Multifunctional Photothermal Structure for Efficient Solar Evaporation, Water Purification, Disinfection, and Power Production.

Development of a hybrid multifunctional photothermal structure with multifunctional capabilities is deliberated as an effective approach for harvesting abundant solar energy for sustainable environmental applications. Achieving enhanced solar to thermal conversion efficiency utilizing a suitably designed, environmentally compatible thermal management structure however remains a significant challenge. Herein, we report the intercalation of V2O5 and polypyrrole into a graphene oxide layer to design a hybrid photothermal assembly (PPy-V2O5-GO) and its multifunctional proficiencies. The hybrid photothermal structure demonstrated synergistic photothermal conversion, buoyant porous structure sustaining water transmission, and efficient steam release. V2O5 and polypyrrole-intercalated optimized graphene oxide structure attained an evaporation rate of 1.9 kg m-2 h-1 with a conversion efficiency of 92% under 1 sun solar radiation. At maximum, the assembly's surface temperature hit 64 ± 2 °C, suggesting its suitability as a solar water purifier. Outdoor experiments suggest the evaporator assembly's capability to accumulate a total output of 15 kg m-2 over a single day. Cell viability investigations revealed strong antimicrobial properties of PPy-V2O5-GO against both Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus bacteria, eliminating nearly all under 1 sun, making it a potential candidate for photothermal therapy. Furthermore, when combined with a commercial thermoelectric module, the framework displayed exceptional photothermal conversion efficiency, hinting at its potential for electrical power generation. The integration of PPy-V2O5-GO with a Bi2Te3-based thermoelectric module significantly boosted the thermoelectric generator's performance, offering an enhanced power output of 2.8 mW and a high power density of 1.24 mW/cm2, making them suitable for off-grid or remote-area application. Overall, the PPy-V2O5-GO photothermal assembly's stability, lack of leaching, effectiveness in producing pure water from seawater, antimicrobial efficacies, and recyclability make it an excellent choice for sustainable water treatment and power generation.

Water Contaminant Detection and Water Purification of Household Drinking Water Using a New Stacking Ensemble Model

ABSTRACTContaminated drinking water sources pose a significant health risk worldwide. Monitoring programs for drinking water quality aims to ensure safe water supply by informing management practices. Improved online monitoring of water systems is necessary as current lab‐based methods are slow and do not offer real‐time public health protection. Rapid detection and response to potential contamination events are crucial to mitigate health risks. Mark of‐purpose water treatment strategies offer a reasonable method for upgrading drinking water quality at the family level and forestalling waterborne illnesses. This study focuses on collecting household drinking water and utilizing various sensors to measure parameters such as pH, turbidity, water level, temperature, and humidity. A consistent water quality noticing system using the stacking outfit model, which solidifies Bayesian association and decision tree techniques, is proposed in this article. Bayesian network analyzes the input data attained from sensors collecting real‐time data and concludes whether the data represents the contamination event. DTs are utilized to demonstrate the connections between multivariate water boundaries utilized in the review. Afterward, a multiobjective, such as a biobjective optimization model and a nondominated genetic algorithm (NGA) are used in this work of optimization to minimize the volume of contaminated water. After the pollution in the water is identified, water decontamination processes are done given point of purpose medicines like ceramic channels and solar water disinfection (SODIS). The method outlined is executed through Python software. The findings indicate that the estimated values for PH, temperature, and turbidity are 7.3, 31.8, and 0.77, respectively. However, the proposed method is compared with the existing C‐NSGA‐II, while compared to this method, the proposed system produces improved cost functions. Consequently, suitable water treatment and supply should be considered to reduce the effects on people's health as well as to improve living conditions, respectively.

Enhancement of solar water disinfection using different types of clay

This study delves into the impact of incorporating natural nanoparticles (mineral clays) into contaminated water during the Solar water disinfection (SODIS) process. The experiment involved introducing contaminated water samples into glass containers containing 1 × 10−3 gm/ml of a specific clay type. These containers were then exposed to solar radiation for varying time intervals. Subsequently, samples were extracted from each container, and the total counts of Total Coliform, P. aeruginosa aeruginosa, and E.coli were measured using the IDEXX setup. The results revealed that Zeolite, a specific type of clay, exhibited the shortest disinfection process among the mineral clay samples. The optimal concentration of Zeolite, which effectively reduced the concentration of Total Coliform, P. aeruginosa, and E.coli concentration, was 1 × 10−3 gm/ml. In conclusion, adding Zeolite to wastewater was observed to positively impact the disinfection process, accelerating the inactivation process by reducing the number of pathogenic microorganisms.

Overview of the low-cost technologies for household water treatment in developing countries

ABSTRACT This study explored various low-cost water treatment technologies that are used to minimize levels of pathogens and contaminants in raw water. The paper focused on techniques such as cloth filtration, boiling, chlorination, and solar water disinfection. In the communities, cloth filtration is applied as the initial step of treating raw water with the proper choice of cloth fabrics followed by either boiling, chlorination or solar water disinfection. In low-income communities with unclean burning fuel sources, boiling was found to be the preferred method. Chlorination was also a popular technique associated with the challenges of low or high levels of free chlorine at the point of use and disinfection by-products. Solar water disinfection required optimal residence time and detection sensors for microorganism inactivation. Overall, the paper provided valuable insights into the different low-cost water treatment techniques that are commonly used for household applications, particularly in developing countries.

SODIS with hydrogen peroxide: an effective household water treatment option under sub-tropical climatic conditions of bangladesh.

Solar disinfection (SODIS) is an affordable and sustainable Household Water Treatment (HWT) method endorsed by WHO. However, its limitations include longer sunlight exposure requirements, incomplete microbial inactivation, and post-SODIS microbial regrowth during monsoon and winter seasons in subtropical climates. To address these limitations, the performance of SODIS with H2O2 for microbial inactivation during the monsoon and winter seasons in Bangladesh was evaluated following the WHO HWT protocols. Moreover, the process was verified using drinking water samples collected from restaurants, households, and slums. All SODIS experiments were conducted using reflective reactors with PET bottles and plastic bags, adding 10 mg/L of H2O2, and exposing them to sunlight for 6 h. The results showed that E. coli was completely inactivated within 2 h in plastic bags and within 3 h in PET bottles during the monsoon season, achieving an LRV of > 5. In winter, both achieved an LRV > 5 within 3 h and plastic bags showed more efficient in microbial inactivation than PET bottles. The microbial inactivation rates were 5 times higher than those of conventional SODIS. No regrowth of microorganisms was observed during the subsequent post-SODIS period of 12 h and 24 h at room temperature. The study findings suggest that SODIS with H2O2 has the potential for complete microorganism inactivation with shorter sunlight exposure in subtropical climates with moderate to low solar irradiation and can be adopted as a reliable disinfection option for rural and urban communities with unsafe drinking water supply.

Solar water disinfection: A probabilistic methodology for predicting exposure period from time series of insolation data

Solar water disinfection: A probabilistic methodology for predicting exposure period from time series of insolation data

THE PRESERVATION OF THE RELIGIOUS CULTURAL PATRIMONY

The present article analyzes the preservation of the religious cultural patrimony of the Catholic Church, whose collection is of great size both in tangible and intangible assets. It is based on concepts related to the patrimony, in accordance to Brazilian law and to deals stablished between Brazil and the Holy See, aiming the universal interest in protecting, promoting and valuing the religious, historical, artistic and cultural patrimony. It showcases local realities of the Society of Saint Francis de Sales in Brazil, specially of the Salesian Province in São Paulo, and of the Salesian Province in Campo Grande. These actions contribute to the historical, artistic and cultural preservation by perpetuating the memorable facts of the church to future generations and by cooperating to spread the knowledge as to correspond to the learning and comprehension of the contexts of each historical period. The preservation of the territory (building/church) has the collective participation and is solidified through religious experiences linked to the sacred place.

Solar Disinfection of Drinking Water in Semi-Temperate Rural Community of Jos, Nigeria

A significant number of the world’s population lacks access to safe drinking water, relying mostly on wells and streams, which are usually contaminated with faeces and other pollutants, as sources of drinking water. This results in many diseases that plague these communities, predominantly in rural areas of developing countries where there is abundant solar radiation all year round. SODIS is a popular method of disinfecting water with remarkable success in many rural areas globally. This method was used in Maza community of Jos North Local Government area of Plateau state in the current study. 2-liter PET bottles, differently modified, were filled with water and placed on corrugated roofing sheets for direct exposure to solar radiation. Some of the bottles were modified by painting them white, white with insulation, half black, black with insulation, and plain with insulation. Delagoa test kits applied to contaminated SODIS bottle showed rapid decrease in the concentration of pathogen at about 40 0C. The Black painted Insulated modified bottle presented the highest maximum temperature of 62.0 0C, which occurred around 2 pm, while the least maximum temperature (53.0 0C) was obtained at the same time for the white modified bottle. Though the plain unmodified bottle showed the least temperature the value was higher than the ambient temperature of Maza. Contrasting the maximum SODIS temperature of the black modified bottle to the corresponding maximum value for the ambient temperature indicates a 29 0C (96.7 %) rise in temperature within 6 hours. SODIS modification, therefore, enhances the temperature of water by several degrees, and can, therefore, be deployed as an alternative means for households in Maza community to access safe drinking water.

Solar Based Water Purification System

Abstract: Solar-based water purification is an innovative and sustainable method leveraging solar energy to produce clean drinking water from contaminated sources. This approach integrates various technologies, primarily solar distillation, solar disinfection (SODIS), and solar-powered filtration systems

Study of the Bunsen–Roscoe Reciprocity Law in Solar Water Disinfection (Optical Effect) for E. coli, E. faecalis and C. perfringens

Water stress and water quality represent major environmental challenges in the 21st century. In response, wastewater management and its potential reuse emerge as strategies to mitigate these problems. This research aims to verify the law of reciprocity in the solar disinfection process of real secondary wastewater effluents for different faecal microorganisms. Flat disinfection reactors, subjected only to natural and continuous UV radiation, were used. The study focused on the optical effect of UV radiation, eliminating the significant influence of the thermal effect and its synergy in solar disinfection at temperatures above 45 °C, by controlling the temperatures of the water samples to levels below 20 °C. Three experimental tests were carried out on sunny days. Each test comprised two trials, under the following conditions: (a) low solar irradiance over a prolonged time (duration approximately: 2.6 h) and (b) high solar irradiance and a shorter period of time (approximately 2 h), with each receiving the same UV dose. Inactivation kinetics was analysed for E. coli, E. faecalis, and C. perfringens (including spores). The results validated the reciprocity law for E. coli in all tests for UV doses > 20 Wh/m2, showing no significant deviations, with inactivation rates of 0.44 to 0.51 m2/Wh for initial concentrations of 106–107 CFU/100 mL. In contrast, for E. faecalis, the reciprocity was only valid at intensities < 700 W/m2, with rates of 0.04 and 0.035 m2/Wh for 105–106 CFU/100 mL; above this irradiance value, the law varied significantly and was not valid. C. perfringens did not show significant disinfection results during the experiments to verify this law, mainly due to the resistance of its spores. Additional experimentation with C. perfringens is necessary, by extending the length of the experiments and/or conducting them at higher irradiance values, in order to reach bacterial inactivation to enable the analysis of the reciprocity law. In general, the main conclusion from these results is that the reciprocity law in solar disinfection would be difficult to use for the estimation of water solar disinfection based on the irradiance and exposure times, as there are deviations from it at least in one specie (E. faecalis). Mores studies should be carried out to fully understand and determine the validity of this law and its potential application for forecasting solar water disinfection.

Interference of bicarbonate and carbonate anions in the solar disinfection of water

Interference of bicarbonate and carbonate anions in the solar disinfection of water

WITHDRAWN: An Investigation of a Hybrid Solar-Mineral Disinfection Technique Using Zeolite and Dead Sea Clay

Effluents from water treatment plants (WTP) can often contain a complex mixture of residual micro-contaminants and organisms, not removed during wastewater treatment. A combined trickling filter, activated sludge treatment, ozonation, membrane filtration, and suspended biofilm reactors have been shown to reduce these contaminants in waste effluent but at high capita cost. This study examined an inexpensive method of purifying water, which combines solar water disinfection with natural mineral clays (SOMIN-DIS). The study involved the addition of two types of mineral clays, Zeolite and Dead Sea minerals, to containers of polluted wastewater, at varying concentrations. The containers were then subjected to different durations of sunlight exposure. Then, samples were taken from all of the containers to quantify the overall numbers of Total Coliform, Pseudomonas aeruginosa (P.aeruginosa), and Escherichia coli (E.coli), utilizing the IDEXX system. The findings indicated that incorporating Dead Sea clay and Zeolite into SODIS-treated wastewater decreased the overall number of harmful microorganisms and shortened the disinfection duration, as compared to using natural minerals and solar water disinfection (SODIS) independently. Additionally, the study determined that the most effective concentration of Dead Sea minerals, resulting in the least amounts of harmful microorganisms and shortest purification duration, was 0.001g/ml. In contrast, the optimum concentration of Zeolite was 0.002g/ml. In general, the addition of Dead Sea and Zeolite minerals to the wastewater increased the inactivation of bacteria under SODIS from 40% to 65%.

Disinfection of Water by Chlorine, Peracetic Acid, Ultraviolet and Solar Radiations: A Review

Disinfection is an essential step during water treatment to ensure the microbiological safety of water for human consumption, and over time, it has been improved and better understood. In this context, this review provides a compilation of information, new insights, and perspectives on the main microorganisms present in supply water, their basic structures, and mechanisms of disinfection via chlorine, peracetic acid (PAA), ultraviolet (UV) radiation and solar disinfection (SODIS). Chlorine is the most common chemical disinfectant, however, there is the formation of toxic by-products, which has stimulated the use of non-chlorinated disinfection methods, such as PAA, UV and SODIS. The main advantages of PAA reported in the literature are its high disinfecting power, the non-formation of toxic/carcinogenic by-products, its ability to generate radicals, such as CH3C(O)O●, HO● and HOO● with or without the use of electromagnetic radiation or thermal energy. The generation of radicals is one of the most used mechanisms to explain the oxidation process during disinfection, which, also prompted studies to use radiation for catalyzing the formation of these radicals. Consequently, physical disinfection processes, such as UV irradiation and SODIS have received significant attention because, in addition to having the ability to damage the RNA (Ribonucleic Acid) and DNA (Deoxyribonucleic Acid) of microorganisms causing their inactivation, these processes also promote the formation of radicals through reactive species that are ubiquitous in natural water. Therefore, the review will be important for studies focused on the process of water disinfection by advanced oxidized processes, especially those that use PAA combined with UV or SODIS.

Innovative DIY drinking water disinfection for underserved communities

Waterborne pathogens threaten 2.2 billion people lacking access to safely managed drinking water services, causing over a million annual diarrheal deaths. Individuals without access to chlorine reagents or filtration devices often resort to do-it-yourself (DIY) methods, such as boiling or solar disinfection (SODIS). However, these methods are not simple to implement. In this study, we introduced an innovative and easily implemented disinfection approach. We discovered that immersing aluminum foil in various alkaline solutions produces alkali-treated aluminum foil (ATA foil) that effectively adsorbs Escherichia coli (E. coli), Salmonella, and Acinetobacter through the generated surface aluminum hydroxide. For example, a 25 cm2 ATA foil efficiently captures all 104E. coli DH5α strains in 100 mL water within 30 min. Using a saturated suspension of magnesium hydroxide, a type of fertilizer, as the alkaline solution, the properties of the saturated suspension eliminate the need for measuring reagents or changing solutions, making it easy for anyone to create ATA foil. ATA foils can be conveniently produced within mesh bags and placed in household water containers, reducing the risk of recontamination. Replacing the ATA foil with a foil improves the adsorption efficiency, and re-immersing the used foil in the production suspension restores its adsorption capacity. Consequently, ATA foil is an accessible and user-friendly alternative DIY method for underserved communities. Verification experiments covering variations in the water quality and climate are crucial for validating the efficacy of the foil. Fortunately, the ATA foil, with DIY characteristics similar to those of boiling and SODIS, is well-suited for testing under diverse global conditions, offering a promising solution for addressing waterborne pathogens worldwide.

The use of Moringa Oleifera and Salvia Hispanica as auxiliaries in the solar disinfection water treatment process by Sodis

Solar Water Disinfection, known as SODIS, is a treatment method involving the exposure of water to solar radiation (UVA light and heat) to eliminate pathogenic microorganisms. Organic coagulants extracted from Moringa oleifera (T1) and Salvia hispanica (T2) were used in conjunction with the filtration process as auxiliaries. This process included sand filters with particle sizes ranging from 0.25 mm to 0.850 mm and a non-woven geotextile placed at its base. After undergoing the coagulation/flocculation/sedimentation/filtration process, the samples were exposed to sunlight in a solar concentrator using bottles painted on half of their surface (PR) and unpainted bottles (BR). The analyzed parameters included physicochemical properties such as pH, electrical conductivity, turbidity, and apparent color, as well as microbiological parameters, including E. coli and total coliforms. The results of physicochemical analyses demonstrated the superiority of T1 in terms of turbidity and apparent color. Regarding microbiological analyses, they showed the effective removal of E. coli and total coliforms, with 100% inactivation observed in the samples. It was observed that the applied treatment sequence significantly reduced the microbiological load of the samples; however, it cannot be stated with certainty whether the coagulants exerted any influence on this result. Keywords: coagulants, coliforms, filtration, microorganisms.