Building Inspection, Diagnosis & Repair Info

Solar Disinfection Water Treatment for Drinking Water

Solar water disinfection & cleaning: how to disinfect water using solar energy: this article explains using solar heating equipment for correcting unsanitary or unsatisfactory drinking water. Solar water disinfection using solarcatalytic treatment (SODIS) has been under test for some time.

Here we report on recent studies that have improved the efficacy of that approach to using solar power to produce potable water.

InspectAPedia tolerates no conflicts of interest. We have no relationship with advertisers, products, or services discussed at this website.

- Daniel Friedman, Publisher/Editor/Author - See WHO ARE WE?


ADVERTISEMENT


Solar Water Treatment for Contamination

Solar water purifiers use solar energy to produce potable (drinking) water from available water sources. In a typical solar water purifier design, sunlight is converted either to electrical energy typically to operate distillation equipment, pumps, or evaporators, or sunlight is used directly in the form of heat to operate a distillation process. Water is vaporized (evaporated) from a storage container. Water vapor is condensed on the under-side of a glass or plastic surface where it runs down to a clean-water collection container.

The most rudimentary "emergency" solar still has been made using clean black plastic trash bags, a hole in the ground, and plants as a moisture source.

Our placeholder photo at page top is a photovoltaic array in use on a restaurant in San Miguel de Allende, Mexico (not powering solar water purification). [Images of solar water disinfection systems sneeded, CONTACT us].

Comparison of Alternative methods for producing potable water using solar power

Watch out: reviewing popular "solar water purification" articles in our research we observe that some writers are confused about the difference between disinfection and purification.

For example, simply using sunlight to heat water in a closed plastic container for some number of hours might reduce the number of bacterial pathogens - those sensitive to high temperatures without having to boil the water. But such water heating may not remove chemical contaminants - though in an open container some volatile chemical components may be driven off or redued.

And without other more effective filtration steps, heating water simply using direct sunlight will not remove fine sediment nor some other pathogens such as giardia cysts, and it may not reliably reduce bacterial contaminants either, depending on the starting level and particular bacteria.

At DRINKING WATER - EMERGENCY PURIFICATION we list methods of emergency drinking water purification and give choices that can be matched to the immediate circumstances;

 

Photocatalytic Enhanced Solar Disinfection of Drinking Water

These comments on use of solar powered equipment for water disinfection are based on "Final Report: Enhanced Photocatalytic Solar Disinfection of Water as Effective Intervention Against Waterborne Diarrheal Diseases in Developing Countries", National Center for Environmental Research, U.S. Environmental Protection Agency et als.

Quoting from the above report (http://cfpub.epa.gov/ncer_abstracts/index.cfm/fuseaction/display.abstractDetail/abstract/8841/report/F)

Conclusions:

Photocatalytic enhanced solar disinfection using NF-TiO2 was responsible for complete inactivation of E. coli in those reactors exposed to both solar and visible light radiation. The presence of NF-TiO2 enhanced the disinfection rate efficiency of E.coli when compared to those experiments where no photocatalyst was used. Practical application of dye solutions as dosimetric indicator appears as very useful for determining the solar radiation dose necessary for waterborne pathogen deactivation.

Solar water disinfection (SODIS) is a simple, environmentally friendly and low cost point-of-use treatment technology for drinking water purification. However, bacterial re-growth after short storage (24 h) of SODIS treated water has been observed.

Seeking for improvements of SODIS performance, reduction of irradiation time and avoidance of bacteria regrowth, solar based-Advanced Oxidation Technologies (AOTs), such as solar TiO2 photocatalysis, are promising enhancements to SODIS. Unfortunately, one of the main problems with the use of conventional TiO2 for solar applications is its limited capability to absorb only the radiation in the UV range, which is only about 5-8% of the total solar radiation.

In this study, we employed novel nanotechnological procedures to synthesize visible light activated nonmetaldoped TiO2 (i.e., nitrogen-doped TiO2) with high surface area and immobilized on appropriate support materials that were used in novel photocatalytic reactors for water purification in rural zones in Mexico as a case study.

In combination with visible light activated TiO2, we also propose to incorporate in our process the V trough solar collector which has never been applied to solar photocatalytic processes in the past, but has much simpler geometry and demonstrated in preliminary results performance comparable to other types of solar collectors.

Because of its simpler geometry, the V trough solar collector is much less expensive and is attractive to applications is developing countries. This overall process for water purification was denominated “Enhanced Photocatalytic Solar Disinfection” (ENPHOSODIS).

A complete inactivation of the bacteria was achieved when using ENPHOSODIS under solar and visible light at three different NF-TiO2 catalyst concentrations.

Under dark conditions, no difference in the bacteria count was observed and no inactivation of E. coli was observed when employing visible light only. pH was an important influence on the bacteria resistence to solar radiation.

E. coli was able to survive for longer radiation periods at pH 7 and 7.5 than at lower or higher pH values (i.e., 6, 6.5 and 8). An azo dye, acid orange 24 (AO24), was explored for the development of a UV dosimetric indicator for disinfection.

Complete color removal was found to be equivalent to that when water submitted to ENPHOSODIS treatment, under the proposed conditions, will get enough energy to deactivate completely the viable helminth eggs present. Different configurations of immobilized TiO2 photocatalytic reactors were tested under real sun conditions.

Experiments under full sun and cloudy conditions showed that these photoreactors are capable of disinfection with an optimum configuration of internal and external coationg along with a compound parabolic collector.

NOTE: The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.

Solar Arrays and Solar Evaporation for Demineralization of Water- Desalination and Demineralization with Solar Evaporation Array (SEA)

...

Continue reading at UV WATER DISINFECTION, PORTABLE or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see these

Recommended Articles

Suggested citation for this web page

SOLAR WATER DISINFECTION at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

Or see this

INDEX to RELATED ARTICLES: ARTICLE INDEX to WATER TREATMENT SYSTEMS

Or use the SEARCH BOX found below to Ask a Question or Search InspectApedia

Ask a Question or Search InspectApedia

Share this article:

Questions & answers or comments about solar water purification & disinfection systems.

Search the InspectApedia website

Need to make a private comment? Email editor@inspectApedia.com. We welcome email with your website content critique, corrections, suggestions or questions. Email is monitored daily but our workload may prevent an immediate reply. For immediate results, we hope you'll first try asking your question using the search box just above.

Citations & Reviewers

In addition to any citations in the article above, a full list is available on request.

  • Blanco-Galvez, Julián, Pilar Fernández-Ibáñez, and Sixto Malato-Rodríguez. "Solar photocatalytic detoxification and disinfection of water: recent overview." Journal of solar energy engineering 129, no. 1 (2007): 4-15. Abstract:
  • Malato, Sixto, Julián Blanco, Diego C. Alarcón, Manuel I. Maldonado, Pilar Fernández-Ibáñez, and Wolfgang Gernjak. "Photocatalytic decontamination and disinfection of water with solar collectors." Catalysis Today 122, no. 1 (2007): 137-149
    Abstract:
    In recent years, there has been a tremendous amount of research and development in the area of photocatalysis, a process included in a special class of oxidation techniques defined as advanced oxidation processes (AOPs), all characterized by the same chemical feature, production of radical dotOH radicals. This paper reviews the use of sunlight to produce the radical dotOH radicals. The systems necessary for performing solar photocatalysis are described. The paper also summarizes most of the research related to solar photocatalytic degradation of water contaminants carried out during recent years, and how it could significantly contribute to the treatment of very persistent toxic compounds. Various solar reactors for photocatalytic water treatment based mainly on non-concentrating collectors erected during the last few years are also described in detail in this review, as well as the use of the solar photocatalytic processes to inactivate microorganisms present in water, placing special emphasis on some experimental systems erected to optimize this disinfecting technique.
  • Todd Woody, "Water-Cleaning Technology Could Help Farmers", The New York Times, 2/17/2014 p. B1
  • [1] Solar Water Purification for the Border: Solar Distillation, Robert Foster, SWTDI, New Mexico State University, Sharon Eby-Martin
    El Paso Solar Energy Association, web search 07/24/2010 - http://www.epsea.org/pdf/borderpact.pdf [Power point presentation]
  • [2] El Paso Solar Energy Association, EPSEA, El Paso Solar Energy Association, P.O. Box 1314, El Paso, Texas 79947l, Email: info@epsea.org, Tel: 915) 867-8173, http://www.epsea.org
    Quoting:
    The El Paso Solar Energy Association (EPSEA) was founded in 1978 and is the oldest, continuously active, local solar organization in the United States. EPSEA publishes a monthly newsletter on solar energy and EPSEA activities. The purpose of EPSEA is to further the development and application of solar energy and related technologies with concern for ecologic, social and economic fabric of the region (West Texas, Southern New Mexico, Northern Mexico). In addition to monthly meetings/seminars, EPSEA conducts technology demonstrations, information booths, and conducts project development work related to renewable energy technologies in the Southwest U.S. and Northern Mexico. EPSEA is a Chapter Member of the Texas State Solar Energy Society, of the American Solar Energy Society. EPSEA is a registered nonprofit 501(c)(3)
  • [3] Handbook: Advanced Photochemical Oxidation Processes. U.S. Environmental Protection Agency US EPA, EPA/625/R-98/004, December 1998, web search 07/20/210 original source: http://www.epa.gov/nrmrl/pubs/625r98004/625r98004.pdf
    Quoting:
    This handbook summarizes commercial-scale system performance and cost data for advanced photochemical oxidation (APO) treatment of contaminated water, air, and solids. Similar information from pilot- and benchscale evaluations of APO processes is also included to supplement the commercial-scale data. Performance and cost data is summarized for various APO processes, including vacuum ultraviolet (VUV) photolysis, ultraviolet (UV)/oxidation, photo-Fenton, and dye- or semiconductor-sensitized APO processes. This handbook is intended to assist engineering practitioners in evaluating the applicability of APO processes and in selecting one or more such processes for site-specific evaluation.
    APO has been shown to be effective in treating contaminated water and air. Regarding contaminated water treatment, UV/oxidation has been evaluated for the most contaminants, while VUV photolysis has been evaluated for the fewest. Regarding contaminated air treatment, the sensitized APO processes have been evaluated for the most contaminants, while VUV photolysis has been evaluated for the fewest.
    APO processes for treating contaminated solids generally involve treatment of contaminated slurry or leachate generated using an extraction process such as soil washing. APO has been shown to be effective in treating contaminated solids, primarily at the bench-scale level.
  • [4] Final Report: Desalination and Demineralization with Solar Evaporation Array (SEA). Investigators: Tipping, Richard H. , DiMuro, Dave , Dixon, Randall , Wofsey, Mike Institution: University of Alabama - Tuscaloosa EPA Project Officer: Nolt-Helms, Cynthia Project Period: August 15, 2008 through August 14, 2009,
    Web search 07/10/2010, original source: http://cfpub.epa.gov/ncer_abstracts/index.cfm/fuseaction/display.abstractDetail/abstract/8845/report/F

    Objective:     With this research we apply theoretical thermodynamic analysis to the problem of solar desalination, and produce a ready-to-use solar evaporation array (SEA) which produces zero brine output and has a low manufacturing cost. This will be deployed in the U.S.A., as well as developing nations in order to increase general health, increase stability of community reliance on salt and chemical contaminated ground water sources.

    Summary/Accomplishments (Outputs/Outcomes): Over the last year, we produced a hand-made SEA unit to test the feasibility of our initial research. Initial results encouraged us to produce a unit that would closely resemble a deployable, mass-produced SEA unit. This required full-sized industrial plastic molds and thermoformed plastic SEA units. After about a year of working to achieve necessary funding to acquire evaluation samples of production SEA Panels, we began in-lab and field-testing of the units. Significant further research and development is needed to increase condensation-gathering efficiency of the units and test the units in real-world applications. Specifically, we hope to gather efficiency data to determine cost-benefit of using an active barrier-cooling system on the condensation barrier. We also hope to optimize geometry of the condensation barrier to encourage water-gathering efficiency.

    Conclusions: In conclusion, we have produced a fully functional system, which can provide potable water from any contaminated water source. Unlike methods that use molecular osmotic screens, the SEA requires minimal maintenance and cannot be rendered useless by dissolved chemicals like chlorine. Most important, the SEA is a good example of sustainable design in that it successfully captured crystalline salt rather than emitting toxic salt brine and the units double as rain-capture devices which may help to eliminate malarial vector breeding on flat roofs.
    Our proposed Phase II objectives and strategies are to gather highly critical data from field tests and more controlled tests to determine optimal SEA design to maximize waterproducing efficiency while hopefully lowering manufacturing complexity and therefore cost per panel. We also need to determine if theoretical advantages provide a high enough cost-benefit ratio to justify increased manufacturing cost. We need to determine best use and types of biocides and /or ultraviolet treatment to control algae and pathogens. We need to determine optimum mixing ratios with untreated water for ground water demineralization. We also need agricultural field-testing to determine best use integration of the SEA system with low-pressure drip-irrigation systems. Finally, we need to test SEA in a variety of configurations and global locations to determine optimum installed best practice for untrained and minimally trained users.
  • [5] Desalination and Demineralization with Solar Evaporation Array (SEA). Tipping, Richard H., DiMuro, Dave, Dixon, Randall, Wofsey, Mike Institution: University of Alabama - Tuscaloosa, EPA Project Officer: Nolt-Helms, Cynthia Project Period: August 15, 2008 through August 14, 2009 , web search 07/24/2010 original source: http://cfpub.epa.gov/ncer_abstracts/index.cfm/fuseaction/display.abstractDetail/abstract/8845/report/F

    Objective:     With this research we apply theoretical thermodynamic analysis to the problem of solar desalination, and produce a ready-to-use solar evaporation array (SEA) which produces zero brine output and has a low manufacturing cost. This will be deployed in the U.S.A., as well as developing nations in order to increase general health, increase stability of community reliance on salt and chemical contaminated ground water sources.

    Summary/Accomplishments (Outputs/Outcomes): In conclusion, we have produced a fully functional system, which can provide potable water from any contaminated water source. Unlike methods that use molecular osmotic screens, the SEA requires minimal maintenance and cannot be rendered useless by dissolved chemicals like chlorine. Most important, the SEA is a good example of sustainable design in that it successfully captured crystalline salt rather than emitting toxic salt brine and the units double as rain-capture devices which may help to eliminate malarial vector breeding on flat roofs.

    Our proposed Phase II objectives and strategies are to gather highly critical data from field tests and more controlled tests to determine optimal SEA design to maximize waterproducing efficiency while hopefully lowering manufacturing complexity and therefore cost per panel. We also need to determine if theoretical advantages provide a high enough cost-benefit ratio to justify increased manufacturing cost. We need to determine best use and types of biocides and /or ultraviolet treatment to control algae and pathogens. We need to determine optimum mixing ratios with untreated water for ground water demineralization. We also need agricultural field-testing to determine best use integration of the SEA system with low-pressure drip-irrigation systems. Finally, we need to test SEA in a variety of configurations and global locations to determine optimum installed best practice for untrained and minimally trained users.
  • [6] Solar Disinfection of Drinking Water: "Final Report: Enhanced Photocatalytic Solar Disinfection of Water as Effective Intervention Against Waterborne Diarrheal Diseases in Developing Countries", National Center for Environmental Research, U.S. Environmental Protection Agency, Investigators: Dionysiou, Dionysios D. , Bandala, Erick R. , Castillo, Jordana , Dunlop, Patrick , Pelaez, Miguel A,
    Institution: University of Cincinnati , NIBEC, School of Electrical and Mechanical Engineering , Universidad de Las Américas-Puebla

    Research Category: Pollution Prevention/Sustainable Development , P3 Challenge Area - Water , P3 Challenge Area - Materials & Chemistry
    Dionysiou DD, Pelaez M, Bandala ER, Gonzalez L, Dunlop PSM, Byrne JA. Solar photocatalytic disinfection of water in developing countries. Poster presented at the 237th American Chemical Society (ACS) National Meeting, Division of Environmental Chemistry, Session on General Papers, Salt Lake City, UT, March 22-26, 2009.
    Quoting from the above report abstract http://cfpub.epa.gov/ncer_abstracts/index.cfm/fuseaction/display.abstractDetail/abstract/8841 and
    http://cfpub.epa.gov/ncer_abstracts/index.cfm/fuseaction/display.abstractDetail/abstract/8841/report/F

    Objective: Providing safe drinking water in developing countries is a major critical necessity. In Latin America and the Caribbean, an important percentage of people in rural areas have no access to safe water supplies. This lack of access to safe drinking water is commonly related to poverty. Mexico is not the exception and the lack of safe drinking water affects both urban and rural areas. Diseases caused by potentially waterborne infectious microorganisms and other water contaminants affect around 6.4% of the total population of the country. The most affected population sector by this type of diseases is the rural population, representing around 25.3% of the Mexican population.

    Solar water disinfection (SODIS) is a simple, environmentally friendly and low cost point-of-use treatment technology for drinking water purification. However, bacterial re-growth after short storage (24 h) of SODIS treated water has been observed. Seeking for improvements of SODIS performance, reduction of irradiation time and avoidance of bacteria re-growth, solar based-Advanced Oxidation Technologies (AOTs), such as solar TiO2 photocatalysis, are promising enhancements to SODIS. Unfortunately, one of the main problems with the use of conventional TiO2 for solar applications is its limited capability to absorb only the radiation in the UV range, which is only about 5-8% of the total solar radiation.

    Approach: In this study, we proposed to use novel nanotechnological procedures to synthesize visible light activated nitrogen-doped TiO2 (N-TiO2) with high surface area and immobilized on appropriate support materials that will be used in novel photocatalytic reactors for water purification in rural zones in Mexico as a case study. In combination with visible light activated TiO2, we also propose to incorporate in our process the V trough solar collector which has simple geometry and demonstrated in preliminary results performance comparable to other types of solar collectors.

    Because of its simpler geometry, the V trough solar collector is much less expensive and is attractive to applications is developing countries. We name this overall process for water purification “Enhanced Photocatalytic Solar Disinfection” (ENPHOSODIS). In addition to the synthesis of visible light activated materials, development of solar photocatalytic reactors and evaluation of their efficiency for water treatment in the target rural areas in Mexico, this project will also include obtaining and documenting information about the health, social, and economic effects of consumption of non safe drinking water in a specific rural, isolated zone of Mexico. This will help understand cultural aspects and enhance public awareness among the inhabitants of the zone for implementation of effective technologies for water purification and protection

    FINAL REPORT:
    Objective: Solar water disinfection (SODIS) is a simple, environmentally friendly and low cost point-of-use treatment technology for drinking water purification. However, bacterial re-growth after short storage (24 h) of SODIS treated water has been observed. Seeking for improvements of SODIS performance, reduction of irradiation time and avoidance of bacteria regrowth, solar based-Advanced Oxidation Technologies (AOTs), such as solar TiO2 photocatalysis, are promising enhancements to SODIS. Unfortunately, one of the main problems with the use of conventional TiO2 for solar applications is its limited capability to absorb only the radiation in the UV range, which is only about 5-8% of the total solar radiation.

    In this study, we employed novel nanotechnological procedures to synthesize visible light activated nonmetaldoped TiO2 (i.e., nitrogen-doped TiO2) with high surface area and immobilized on appropriate support materials that were used in novel photocatalytic reactors for water purification in rural zones in Mexico as a case study. In combination with visible light activated TiO2, we also propose to incorporate in our process the V trough solar collector which has never been applied to solar photocatalytic processes in the past, but has much simpler geometry and demonstrated in preliminary results performance comparable to other types of solar collectors. Because of its simpler geometry, the V trough solar collector is much less expensive and is attractive to applications is developing countries. This overall process for water purification was denominated “Enhanced Photocatalytic Solar Disinfection” (ENPHOSODIS).

    Summary/Accomplishments (Outputs/Outcomes): A     complete inactivation of the bacteria was achieved when using ENPHOSODIS under solar and visible light at three different NF-TiO2 catalyst concentrations. Under dark conditions, no difference in the bacteria count was observed and no inactivation of E. coli was observed when employing visible light only. pH was an important influence on the bacteria resistence to solar radiation. E. coli was able to survive for longer radiation periods at pH 7 and 7.5 than at lower or higher pH values (i.e., 6, 6.5 and 8). An azo dye, acid orange 24 (AO24), was explored for the development of a UV dosimetric indicator for disinfection

    . Complete color removal was found to be equivalent to that when water submitted to ENPHOSODIS treatment, under the proposed conditions, will get enough energy to deactivate completely the viable helminth eggs present. Different configurations of immobilized TiO2 photocatalytic reactors were tested under real sun conditions. Experiments under full sun and cloudy conditions showed that these photoreactors are capable of disinfection with an optimum configuration of internal and external coationg along with a compound parabolic collector.

    Conclusions: Photocatalytic enhanced solar disinfection using NF-TiO2 was responsible for complete inactivation of E. coli in those reactors exposed to both solar and visible light radiation. The presence of NF-TiO2 enhanced the disinfection rate efficiency of E.coli when compared to those experiments where no photocatalyst was used. Practical application of dye solutions as dosimetric indicator appears as very useful for determining the solar radiation dose necessary for waterborne pathogen deactivation.

    Proposed Phase II Objectives and Strategies: Large scale testing of immobilized NF-TiO2 in model “real water” using real sunlight and CPC’s. Use a more disinfection resistant organisms rather than E. coli under experimental and “real water” conditions. Test the efficiency of system using a real drinking water source in rural location in Mexico.
  • [7] "Solar Water Disinfection", Swiss Federal Institute of Environmental Science and Technology; 2002
  • [8] Household Water Treatment and Safe Storage, World Health Organization
  • [9] Solar Disinfection of Drinking Water and Diarrhoea in Maasai Children;R.M. Conroy et al.; Lancet; March 1997
  • [10] Potable Aqua® emergency drinking water germicidal tablets are produced by the Wisconsin Pharmacal Co., Jackson WI 53037. 800-558-6614 pharmacalway.com
  • [11] Principles and Practice of Disinfection, Preservation and Sterilization (Hardcover)
    by A. D. Russell (Editor), W. B. Hugo (Editor), G. A. J. Ayliffe (Editor), Blackwell Science, 2004. ISBN-10: 1405101997, ISBN-13: 978-1405101998.
  • [12] Handbook of Disinfectants and Antiseptics, Joseph M. Ascenzi (Editor), CRC, 1995, ISBN-10: 0824795245 ISBN-13: 978-0824795245 "The evaluation of chemical germicides predates the golden age of microbiology..." -
    This well-focused, up-to-date reference details the current medical uses of antiseptics and disinfectants -- particularly in the control of hospital-acquired infections -- presenting methods for evaluating products to obtain regulatory approval and examining chemical, physical, and microbiological properties as well as the toxicology of the most widely used commercial chemicals.
  • [13] When Technology Fails, Matthew Stein, Chelsea Green Publisher, 2008,493 pages. ISBN-10: 1933392452 ISBN-13: 978-1933392455, "... how to find and sterilize water in the face of utility failure, as well as practical information for dealing with water-quality issues even when the public tap water is still flowing". Mr. Stein's website is www.whentechfails.com/
  • [14] "How do I Use Solar Power To Purify Water?", Jessica Blue, Demand Media, The National Geographic, online website article, web search 7/30/12, original source: http://greenliving.nationalgeographic.com/use-solar-power-purify-water-3062.html
  • In addition to citations & references found in this article, see the research citations given at the end of the related articles found at our suggested

    CONTINUE READING or RECOMMENDED ARTICLES.

ADVERTISEMENT