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 Solar Disinfection Water Treatment for Drinking Water
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InspectAPedia tolerates no conflicts of interest. We have no relationship with advertisers, products, or services discussed at this website.
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.
Green links show where you are. © Copyright 2013 InspectAPedia.com, All Rights Reserved. Author Daniel Friedman.
Solar Water Treatment for Contamination
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).
For explanation of the types of contaminants found in water and how they are removed in residential water systems, see WATER TESTS, CONTAMINANTS, TREATMENT. See WATER TREATMENT EQUIPMENT CHOICES for details on other water treatment options. See Filters for Drinking Water Purification for a discussion of portable and emergency water filters that are designed to purify drinking water, including portable ceramic water filters, silver ceramic filters, magnetic (bogus) water purifiers, paper and polypropylene water filters, etc.
See DRINKING WATER PURIFICATION for a discussion of various methods used to purify emergency drinking water. A companion article, DRINKING WATER - EMERGENCY SOURCES,describes possible sources of drinking water that may be useful in emergency conditions.
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.
Comparison of Alternative methods for producing potable water using solar power
- Photocatalytic enhanced solar disinfection using NF-TiO2 (reported below in this article). Keep in mind that the SODIS approach is aimed at reducing bacterial contamination only.
- Solar powered desalinization or demineralization (see references below) - removing salt, e.g. from seawater
- Solar purifiers using solar-powered water distillation. Note that water distillation removes most contaminants.
- Aqua Sun, Aqua Sun International, Inc. 1617 Water St. Suite J, Minden, NV (775) 783-8566 - portable, mobile, and stationary solar powered water purification systems, also produce solar water pumping systems - www.aqua-sun-intl.com/. Output capacity for stationary water purification systems varies by model, ranging from 1 gpm to a system capable of producing more than 8,600 gallons per day. Quoting:
The concept of combining solar energy and water purification into a single, completely self-contained water purification system was invented and developed by Aqua Sun in 1990.
- Solar Water Purifier, +61 3 9563 8120, produces solar arrays, 4-panel and 12-panel systems with capacity of 2-4 liters/day per panel. - www.sunsurewater.com
Quoting
Easily erected and plumbed this Waterward kit just needs sunshine! Providing an average of 2 to 4 litres per day from a single panel. It will provide safe drinking water for the family. The panels easily convert grey, sea, bore, tap, rainwater etc into extremely pure water safe for personal use.
- Safe Water Systems, 1600 Kapiolani Blvd., Suite 721 Honolulu, HI 96814, Phone: 808-949-3123 Fax: 808-949-3103
Email: info@safewatersystems.com - www.safewatersystems.com
Quoting:
... specialize in products that utilize solar energy to disinfect and purify water, desalinate water and pump water in areas where conventional water treatment facilities are not available.
- Also see SOLAR ENERGY SYSTEMS
- Photochemical Oxidation - APO - not suitable for drinking water: see Handbook: Advanced Photochemical Oxidation Processes. U.S. Environmental Protection Agency US EPA - "APO has been shown to be effective in treating
contaminated solids, primarily at the bench-scale level."
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; also at WATER TREATMENT EQUIPMENT CHOICES we list types of water treatment equipment and methods and the features of each.
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)
Pros/Cons: Advantages and Problems with Various Types of Water Treatment Equipment for Bacterial or Bacteriological Contamination
- Water Filters as Purifiers (introduction) and Filters for Drinking Water Purification (details including portable ceramic water filters, silver ceramic filters, magnetic (bogus) water purifiers, paper and polypropylene water filters, etc. )
- UV -ULTRAVIOLET LIGHT TREATMENT as a Water Purifier
- REVERSE OSMOSIS WATER TREATMENT Systems for Water Purification
- CHLORINATORS & CHARCOAL FILTERS for Water Purification
- Aesthetic water contaminants and treatment systems: sediment, iron, odors, taste
- WATER SOFTENERS & CONDITIONERS for correcting "hard" water - clogs pipes, poor washing & bathing, mineral deposits, reduced hot water output from water heaters and tankless coils
- Sediment filters and Iron filters to reduce red iron stains on fixtures & clothings
- Sulphur odor filters or Sulphur Treatment Systems - get rid of that "rotten egg" smell
- WATER TREATMENT CHEMICAL SAFETY Warnings
List of Principal Methods Used to Purify Contaminated Drinking Water when Camping or in an Emergency
- Boil the water to make it suitable for drinking. See Boiling Water for Drinking.
- Bleach: Use chlorine (bleach, sodium hypochlorite) to purify the water. (see warnings just above). See Bleach as a Disinfectant for Drinking Water. Permanent well water chlorination systems are discussed at CHLORINATORS & CHARCOAL FILTERS.
- Ceramic water filters - see Filters for Drinking Water Purification
- Chlorination: where electrical power and water pressure are present and the equipment is already installed, a chlorinator or water chlorine injection treatment system, usually combined with a charcoal filter for water treatment may be functional. See CHLORINATORS & CHARCOAL FILTERS for details.
- Giardia in Drinking Water - a review of the health hazards & typical equipment costs for portable and whole house water treatment to remove Giardia cysts from drinking water
- Iodine: Use Iodine tablets or a liquid tincture of iodine to purify the water for emergency use (see warnings just above). See Iodine Tablets or Iodine Disinfectant.
- Hydrogen peroxide may be used (maybe) to purify water for emergency drinking use. [The concentration and exposure time data are still needed for this application.]
- Water purifying filters: Use a filter designed for water purification, particularly ceramic filters and silver-ceramic filters. See WATER FILTERS for a separate discussion of home water filters used for sediment, odors, etc.
- Use a water purifying pump such as models sold by camping equipment suppliers to purify the water - typically these pumps use a ceramic or other filter. See Filters for Drinking Water Purification for information about pump type ceramic water filters.
- Use a water distiller such as a home or portable distillation unit (our photo just above/left shows a Sears® Kenmore home water distiller) (You'll need electrical power or a source of heat to distill water). This device processes about one gallon of water per cycle. We have been using this Sears Kenmore water distiller, model 5000 for more than fifteen years without a hitch. A disposable charcoal post-distillation filter is available for use in the drip spout of the unit - a potential source of contamination if it is not changed occasionally.
- Reverse osmosis: use a Reverse osmosis water filtration system if water pressure is available or if a portable R.O. system is available. See REVERSE OSMOSIS WATER TREATMENT for details. RO treatment systems may work where there is no electrical power provided that you have water pressure, such as in some municipal water situations.
- UV Lights - ultra violet light used for water sterilization - see UV -ULTRAVIOLET LIGHT TREATMENT
- Vinegar is sometimes used as a vegetable wash and may be effective against some microorganisms in water - we have not yet found authoritative data on this application. See Vinegar & Other Disinfectants.
- Mixed oxidants electrochemically generated from brine have been used for water disinfection
- Halogenated resins have been used for water disinfection
- Home Made & Expedient Water Sterilization Methods: Matthew Stein describes a variety of home-made, expedient, and partly effective water filters and water treatment methods in When Technology Fails. With plastic and a few sticks you can build a solar water sterilizer (solar water disinfection or SODIS systems).
Stein also explains that slow sand filters have been used for partially cleaning and treating water for a very long time. A crude home made charcoal filter will remove some odors, bad tastes, organic toxic chemicals, and radioactive fallout. Mr. Stein also describes sari water filters used in Bangladesh after flooding, but includes a critical warning that filtering water through cloth is by no means really safe.
Our favorite of his suggestions is using a plant to form a water collector and filter system, an idea which reminds us of native Americans who knew how to obtain water from desert barrel cactus. We enjoyed this book and provide this purchase link for it.
- Hydrogen Peroxide for Water Disinfection
- Solar Disinfection of Drinking Water: 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.
Basic water purification procedures that can be used in an emergency are described just below. If community or private wells are back in operating and providing water, do not assume that the water is sanitary and ok to drink until responsible authorities have said so. Even then, local water pipes in a building may be unsanitary and additional cleaning or disinfection may be needed. See WELL CHLORINATION SHOCKING PROCEDURE and See WATER TESTS, CONTAMINANTS, TREATMENT for advice on using a private well for drinking water.
Frequently Asked Questions (FAQs)
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Technical Reviewers & References
Related Topics, found near the top of this page suggest articles closely related to this one.
- [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.
"This superb book is the best of its kind available and one that will undoubtedly be useful, if not essential, to workers in a variety of industries. Thirty-one distinguished specialists deal comprehensively with the subject matter indicated by the title ... The book is produced with care, is very readable with useful selected references at the end of each chapter and an excellent index. It is an essential source book for everyone interested in this field. For pharmacy undergraduates, it will complement the excellent text on pharmaceutical microbiology by two of the present editors."
The Pharmaceutical Journal: "This is an excellent book. It deals comprehensively and authoritatively with its subject with contributions from 31 distinguished specialists. There is a great deal to interest all those involved in hospital infection ... This book is exceptionally well laid out. There are well chosen references for each chapter and an excellent index. It is highly recommended." The Journal of Hospital Infection.: "The editors and authors must be congratulated for this excellent treatise on nonantibiotic antimicrobial measures in hospitals and industry ... The publication is highly recommended to hospital and research personnel, especially to clinical microbiologists, infection-control and environmental-safety specialists, pharmacists, and dieticians."
New England Journal of Medicine: City Hospital, Birmingham, UK. Covers the many methods of the elimination or prevention of microbial growth. Provides an historical overview, descriptions of the types of antimicrobial agents, factors affecting efficacy, evaluation methods, and types of resistance. Features sterilization methods, and more. Previous edition: c1999. DNLM: Sterilization--methods.
- [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
How Do I Use Solar Power to Purify Water?
Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair
- Our recommended books about building & mechanical systems design, inspection, problem diagnosis, and repair, and about indoor environment and IAQ testing, diagnosis, and cleanup are at the InspectAPedia Bookstore. Also see our Book Reviews - InspectAPedia.
 The Home Reference Book - the Encyclopedia of Homes, Carson Dunlop & Associates, Toronto, Ontario, 25th Ed., 2012, is a bound volume of more than 450 illustrated pages that assist home inspectors and home owners in the inspection and detection of problems on buildings. The text is intended as a reference guide to help building owners operate and maintain their home effectively. Field inspection worksheets are included at the back of the volume. Special Offer: For a 10% discount on any number of copies of the Home Reference Book purchased as a single order. Enter INSPECTAHRB in the order payment page "Promo/Redemption" space. InspectAPedia.com editor Daniel Friedman is a contributing author.
Or choose the The Home Reference eBook for PCs, Macs, Kindle, iPad, iPhone, or Android Smart Phones. Special Offer: For a 5% discount on any number of copies of the Home Reference eBook purchased as a single order. Enter INSPECTAEHRB in the order payment page "Promo/Redemption" space.
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