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Solar water pasteurisation literature review

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This literature review focuses on low-cost OSAT to make biologically-contaminated water safe to drink. It is concentrated on papers after 2000.

See also Decreasing turbidity to optimize solar water disinfection lit review

Contents

The Need for Safe Drinking Water Worldwide[edit]

Water disinfection for developing countries and potential for solar thermal pasteurization[1][edit]

Abstract: Water-borne disease in developing countries leads to millions of deaths and billions of illnesses annually. Water disinfection is one of several interventions that can improve public health, especially if part of a broad program that considers all disease transmission routes and sustainably involves the community.

  • There are four methods being used to sanitize water worldwide:
    • Chlorination
      • Most common form of desalination
      • Relatively low cost estimated to be about a cent per gram of water
      • Difficult to measure accurate amounts
    • Filtration
      • Three main types:
        • Roughing filter
        • Slow sand filter
        • Household filter
    • UV radiation
      • A germicidal wavelength of 200 to 280 can be achieved relatively easily and can be applied to small scale and/or village use.
    • Pasteurization
      • The thermal disinfection of liquids
      • Pasteurization temperatures can be reached at much lower than boiling temperature.
      • Domestic use has a high fuel and labor cost
      • Flow through solar units have the potential to be very effective

A Mathematical Model[edit]

Formulation of a mathematical model to predict solar water disinfection[2][edit]

Link to full text:

A mathematical model was formulated that will facilitate the prediction of solar disinfection by analyzing the effect of sunlight exposure (x1) and the load of bacterial contamination (x2), as predictor variables, on the efficiency of solar disinfection (y).

  • The exposure required to produce a given decontamination level can be predicted using the equation: x1=(-1/k)ln[1-(1-y)-1/x2]e(-μ/ρ)*(m/A)
    • kis the solar inactivation constant
    • μ is the linear attenuation coefficient (m-1)
    • ρ is the density
    • m is the mass
    • A is the area of the exposed part of the sample

Data showed that disinfection is dependent both on the load of bacterial contamination and sunlight exposure. This relationship is characterized by curves having shoulders followed by a steep decline and then tailing off in an asymptotic fashion.

Literature Review[edit]

Link to Decreasing Water Turbidity Literature Review: [1]

Solar Box Cookers[edit]

Enhancement of Solar Water Pasteurization with Reflectors[3][edit]

Abstract: A simple and reliable method that could be used in developing countries to pasteurize milk and water with solar energy is described. A cardboard reflector directs sunshine onto a black jar, heating water to pasteurizing temperatures in several hours. A reusable water pasteurization indicator verifies that pasteurization temperatures have been reached. http://aem.asm.org/content/65/2/859.short

  • Utilized reflectors to concentrate the sunlight on a black spot
  • Black spot transformed radiant energy to heat
  • Modified from SCI's Cookit design, which utilizes the sun's rays to cook food.
  • A soy bean indicator which melts at about 70 degrees centigrade was a visual tool used to indicate pasteurization.

A 12 month field test on children ages 5 to 16 in Kenya found that children who drank the water that stayed inside had more diarrhea than the children that drank the water heated outside in the sun. However, if the numbers were projected over a one year time span, the percentage difference was only 1.7 percent (from 17.8 to 19.5).

Pasteurization of naturally contaminated water with solar energy[4][edit]

A solar box cooker (SBC) was constructed with a cooking area deep enough to hold several 3.7-liter jugs of water, and this was used to investigate the potential of using solar energy to pasteurize naturally contaminated water. http://aem.asm.org/content/47/2/223.short

Materials and Methods[edit]
  • They modeled their SBC after the Kerr-Cole Eco-Cooker (1976)
  • Consists of three basic components:
    • A large, well insulated cardboard box with a rectangular cooking area
    • A removable cardboard lid with a glass window
    • A hinged adjustable reflector lid attached to the lid
Results[edit]
  • Orientation of the water jug inside of the SBC had a difference
    • They tested a jug on the east side
      • Heated more rapidly after 2 p.m.
    • They tested a jug on the west side
      • Heated more rapidly before noon

When river water was heated either in the SBC or on a hot plate, coliform bacteria were inactivated at temperatures of 60 degrees C or greater. Heating water in an SBC to at least 65 degrees C ensures that the water will be above the milk pasteurization temperature of 62.8 degrees C for at least an hour, which appears sufficient to pasteurize contaminated water. Link to full text PDF:

Solar water-water-sterilization system with thermally-controlled flow[5][edit]

Link to full text:

Abstract: The presented system is used to produce relatively larger amounts of sterilized water than by merely putting a fixed amount of contaminated water in a small bottle inside a hot box solar cooker (HBSC).

  • Hot box solar cooker incorporates double glazing spaced .04 m apart to reduce the upward heat losses.

A set of simplifying assumptions were made:

  • The various components of the cooker are at different but uniform temperatures at any given time.
  • Solar radiation is incident only on the absorber plate, water glass jar and water inside it.
  • Solar cooker has six components and mathematical models (see full text) to describe each element:
    • Upper transparent cover
    • Lower transparent cover
    • Internal air
    • Water glass jar
    • Absorber plate
    • Water inside glass container

For achieving a specified temperature with the HBSC, a thermostat attached to a solenoid valve is placed at the outlet port of the HBSC to ensure that the desired temperature corresponds to the water-sterilization temperature. A basic heat transfer analysis is done for the HBSC to find the effect of environmental conditions for the behavior of the system.

  • Thermal and biological tests of the water samples during the sterilization process are obtained.
    • The performance data collected for the systems indicates that there was good viability for solar energy in sterilizing contaminated water.

Increased Efficiency by Heat Exchange[edit]

Expanded microchannel heat exchanger: design, fabrication, and preliminary experimental test[6][edit]

This article describes the advantages of using a Heat Exchanger (HX), and how they can be incorporated into a solar water pasteurization project.

  • A HX can be fabricated with microchannels by using a laser welder to melt specific points into cheap or recycled polymer.
  • In order to weld polymers, the welding temperature must be above the polymer's melting point, but below its decomposition point.

Two possible failure concerns:

  • Channel Erosion
  • Fouling

Typical HX effectiveness range is from 60 to 80 percent

A new model for HX has been proposed in the article:

  • Expands the HX vertically along its y-axis, looking at it through it's channels.
  • Contracts the HX horizontally along its x-axis, at the same point of view.

Polymer microchannels can be expanded using pressurized fluid

  • Rupture results in contamination of clean water, so expanding the microchannels poses a difficult challenge.

Abstract:

A simple high efficiency solar water purification system[7][edit]

Abstract:

A new passive solar water pasteurization system based on density difference flow principles has been designed, built and tested. The system contains no valves and regulates flow based on the density difference between two columns of water. The new system eliminates boiling problems encountered in previous designs. Boiling is undesirable because it may contaminate treated water. The system with a total absorber area of 0.45 m2 has achieved a peak flow rate of 19.3 kg/h of treated water. Experiments with the prototype systems presented in this paper show that density driven systems are an attractive option to existing solar water pasteurization approaches.

  • There are two types of passive solar pasteurizers: batch and continuous flow.
    • Both types include a HX.
    • batch incorporates a refillable water vessel and thermostatic valve
      • thermostatic valve has trouble regulating temperature, because the water trough has to heat the water by about 60 degrees centigrade at the start of the heating day.
      • Once the HX warms up, the water in the trough only needs to be heated by about 10 degrees centigrade
    • continuous flow is circular and is heated by thin tubes
      • Density driven system incorporates tubing that will only allow water to pass if it is above a certain temperature.

A pilot solar water disinfecting system: performance analysis and testing[8][edit]

Link to full text:

A solar radiation model is presented and compared with the experimental data. A mathematical model of the solar disinfectant is also presented. The governing equations are solved numerically via the fourth-order Runge–Kutta method. The effects of environmental conditions (ambient temperature, wind speed, solar radiation, etc.) on the performance of the solar disinfectant are examined.

  • Results showed that the system is affected by ambient temperature, wind speed, ultraviolet solar radiation intensity, the turbidity of the water, the quantity of water exposed, the contact area between the transparent water container in the solar disinfectant and the absorber plate as well as the geometrical parameters of the system.
  • Experimental set up included:
    • 100 L contaminated water storage bin
    • Preliminary water filter
    • Concentric double pipe counter flow heat exchanger
    • cubic glass container situated inside a solar disinfectant via a silicon braid hose.
    • cold water outlet port from HX
    • Transparent glass container for solar heating of contaminated water
    • Clean water tank

For partially cloudy conditions with a low ambient temperature and high wind speeds, the thermal efficiency of the solar disinfectant is at a minimum.

Effectiveness--thermal resistance method for heat exchanger design and analysis[9][edit]

Link to full text: http://www.sciencedirect.com/science/article/pii/S0017931010000669

Abstract:

The equivalent thermal resistance of a heat exchanger is defined based on the concept of the entransy dissipation rate, which measures the irreversibility of heat transfer for the purpose of object heating or cooling, rather than from the heat to work conversion. The relationships between the heat exchanger effectiveness and the thermal resistance (or conductance) are developed, which do not depend on its flow arrangement, and hence useful for the performance comparison among heat exchangers with different flow arrangements. In addition, such relationships bridge a gap between the heat exchanger irreversibility and its effectiveness. The monotonic decrease of the effectiveness with increasing the thermal resistance shows that the heat exchanger irreversibility can be described by its thermal resistance when evaluated from the transport process viewpoint, while the so-called entropy generation paradox occurs, if the irreversibility is measured by the entropy generation number for a heat exchanger.

Fluid Flow and Heat Transfer at Micro- and Meso-Scales With Application to Heat Exchanger Design[10][edit]

URL:

Abstract

By their very nature, compact heat exchangers allow an efficient use of material, volume, and energy in thermal systems. These benefits have driven heat exchanger design toward higher compactness, and the trend toward ultra-compact designs will continue. Highly compact surfaces can be manufactured using micro-machining and other modern technologies. In this paper, unresolved thermal-hydraulic issues related to ultra-compact designs are discussed, and the status of the technologies required for the production of ultra-compact structured surfaces is summarized.

Solar HX Patents[edit]

By Date:

Solar Disinfection (SODIS)[edit]

Effect of solar water disinfection (SODIS) on model microorganisms under improved and field SODIS conditions[11][edit]

Abstract: SODIS is a solar water disinfection process which works by exposing untreated water to the sun in plastic bottles. Field experiments were carried out in Cochabamba, Bolivia, to obtain standard UV-A (320-405 nm) dose values required to inactivate non-spore forming bacteria, spores of Bacillus subtilis, and wild type coliphages.

  • Inactivation kinetics for non-spore forming bacteria are similar under SODIS conditions, exhibiting dose values ranging between 15 and 30 Wh m 2 for 1 log10 (90%) inactivation, 45 to 90Wh m-2 for 3 log10 (99.9%), and 90 to 180Wh m-2 for 6 log10 (99.9999%) inactivation.
  • Pseudomonas aeruginosa was found to be the most resistant and Salmonella typhi, the most sensitive of the non-sporulating organisms studied here.
  • Phages and spores serve as model organisms for viruses and parasite cysts.

A UV-A dose of 85 to 210Wh m-2 accumulated during one to two days was enough to inactivate 1 log10 (90%) of these strong biological structures. The process of SODIS depended mainly on the radiation dose [Wh m-2] an organism was exposed to an irradiation intensity exceeding some 12Wm-2 did not increase the inactivation constant.

Solar radiation disinfection of drinking water at temperate latitudes: Inactivation rates for an optimized reactor configuration[12][edit]

Abstract: Solar radiation-driven inactivation of bacteria, virus and protozoan pathogen models was quantified in simulated drinking water at a temperate latitude (34°S).

  • The water was seeded with
    • Enterococcus faecalis
    • Clostridium sporogenes spores
    • P22 bacteriophage

Each at ca 1 × 105 m L−1, and exposed to natural sunlight in 30-L reaction vessels. Water temperature ranged from 17 to 39 °C during the experiments lasting up to 6 h.

  • Dark controls showed little inactivation and so it was concluded that the inactivation observed was primarily driven by non-thermal processes.

The optimised reactor design achieved S90 values (cumulative exposure required for 90% reduction) for the test microorganisms in the range 0.63–1.82 MJ m−2 of Global Solar Exposure (GSX) without the need for TiO2 as a catalyst.

  • Inactivation was significantly reduced for E. faecalis and P22 when the transmittance of UV wavelengths was attenuated by water with high colour (140 PtCo units) or a suboptimally transparent reactor lid (prob. < 0.05).
  • S90 values were consistent with those measured by other researchers (ca 1–10 MJ m−2) for a range of waters and microorganisms.

Although temperatures required for SODIS type pasteurization were not produced, non-thermal inactivation alone appeared to offer a viable means for reliably disinfecting low colour source waters by greater than 4 orders of magnitude on sunny days at 34°S latitude.

Solar photo-oxidative disinfection of drinking water: preliminary field observations[13][edit]

Abstract: The feasibility of using solar photo-oxidation to inactivate faecal bacterial contaminants in drinking water has been evaluated under field conditions in India and South Africa. Freshly drawn samples from all six test water sources were low in dissolved oxygen, at 13–40% of the air saturation value. However, vigorous mixing followed by exposure to full-strength sunlight in transparent plastic containers (1–25 l capacity) caused a rapid decrease in the counts of faecal indicator bacteria, giving complete inactivation within 3–6 h, with no evidence of reactivation.

  • These results demonstrate that solar photo-oxidation may provide a practical, low-cost approach to the improvement of drinking water quality in developing countries with consistently sunny climates.

Link to full text:

A mobile solar water heater for rural housing in Southern Africa[14][edit]

Link to full text:

Abstract: An affordable device was envisaged that could assist in rural areas with the transportation and heating of water. Southern Africa is blessed with abundant sunshine, thus making it appropriate to select solar heating for this purpose.

  • Three types of solar water heaters manufactured for domestic use:
    • Two-component split-systems with a flat plate collector and direct or indirect water heater
      • Most expensive
    • Close-coupled systems with direct or indirect heating and a separate water storage tank situated at the elevated end of the collector
      • Close-oupled systems are usually cheaper and easier to install than the split system
    • Integrated collector storage (ICS), where the storage of hot water is integrated into the direct heating collector
      • These are the cheapest but also the least efficientThe device must have the ability to store the hot water until the evening.

An ICS type solar water heater, with insulation and glazing, was selected.

  • ICS system performs better, and for a lower initial cost, than classical systems for 10 months of the year
  • Mobility of the device was modelled after the wheelbarrow
  • Device was named the Solar Heat Barrow.

Prototypes were designed, manufactured and tested and it was demonstrated that water could be heated to an average of 60 °C by mid-afternoon. Water at 40 °C was still available at 8 pm.

  • Problems experienced during both the manufacture and testing of the device will be solved as development continues.

Disinfection of Contaminated water by using solar irradiation[15][edit]

Link to full text:

A portable, low-cost, and low-maintenance solar unit to disinfect unpotable water has been designed and tested. The solar disinfection unit was tested with both river water and partially processed water from two wastewater treatment plants. The SODIS unit that was prototyped and tested had a thin base and a cover:

  • The base consisted of grooves that ran in an anti parallel snaking pattern.
    • increases surface area of heating
    • increases the amount of time that the water spends in the heated tubing
  • A UV transparent acrylic plate permanently covered the base
    • keeps heat inside
    • Does not allow any air to enter the system

The solar disinfection unit has been field tested by Centro Panamericano de Ingenieria Sanitaria y Ciencias del Ambiente in Lima, Peru.

  • At moderate light intensity, the solar disinfection unit was capable of reducing the bacterial load in a controlled contaminated water sample by 4 log10 U and disinfected approximately 1 liter of water in 30 min.
    • In less than 30 min in midday sunlight, the unit eradicated more than 4 log10 U (99.99%) of bacteria contained in highly contaminated water samples.

Decontamination of drinking water by direct heating in solar panels[16][edit]

Link to full text:

A device was developed for direct heating of water by solar radiation in a flow-through system of copper pipes.

  • An adjustable thermostat valve prevents water below the chosen temperature from being withdrawn.
    • When water reaches the target temperature, the thermostat valve opens and new contaminated water enters the copper pipes.
  • Artificial additions ofSalmonella typhimurium, Streptococcus faecalis and Escherichia coli to contaminated river water were inactivated after heating to 65 °C and above.
  • To provide a good safety margin it is recommended that an outlet water temperature of 75 °C be used.
  • The total viable count could be reduced by a factor of 1000.

The heat-resistant bacteria isolated from the Mlalakuva River (Tanzania) were spore-forming bacteria which exhibited greater heat resistance than commonly used test bacteria originating from countries with colder climates. At that temperature the daily production was about 50 l of decontaminated water per m2 of solar panel, an amount that could be doubled by using a heat exchanger to recycle the heat.

Inactivation of fecal bacteria in drinking water by solar heating[17][edit]

Water samples, heavily contaminated with a wild-type strain of Escherichia coli (starting population = 20 x 10(5) CFU/ml), are heated to those temperatures recorded for 2-liter samples stored in transparent plastic bottles and exposed to full Kenyan sunshine (maximum water temperature, 55 degrees C).

  • The samples are completely disinfected within 7 h, and no viable E. coli organisms are detected at either the end of the experiment or a further 12 h later, showing that no bacterial recovery has occurred.
  • Materials and Method
    • 2-liter plastic bottles were collected, disinfected and had their plastic labels removed.
    • Contaminated water was exposed to sunlight from 8 am to 5 pm.
    • Plastic bottles were oriented on their sides on the ground
    • Samples were tested for turbidity

Link to full text

Development and Evaluation of a Reflective Solar Disinfection Pouch for Treatment of Drinking Water[18][edit]

Link to full text:

Abstract: A second-generation solar disinfection (SODIS) system (pouch) was constructed from food-grade, commercially available packaging materials selected to fully transmit and amplify the antimicrobial properties of sunlight. Depending upon the season, water source, and challenge organism, culturable bacteria were reduced between 3.5 and 5.5 log cycles.

The system was also capable of reducing the background presumptive coliform population in nonsterile river water below the level of detection. Similar experiments conducted with a model virus, the F-specific RNA bacteriophage MS2, indicated that the pouch was slightly less efficient, reducing viable plaques by 3.5 log units in comparison to a 5.0 log reduction of enterotoxigenic Escherichia coli O18:H11 within the same time period.

These results suggest that water of poor microbiological quality can be improved by using a freely available resource (sunlight) and a specifically designed plastic pouch constructed of food-grade packaging materials.

simulation of solar radiation for global assessment and application for point-of-use water treatment in Haiti[19][edit]

Link to full text:

Abstract: Haiti and other developing countries do not have sufficient meteorological data to evaluate if they meet the solar disinfection (SODIS) threshold of 3–5 h of solar radiation above 500 W/m2, which is required for adequate microbial inactivation in drinking water.

A mathematical model was developed based on satellite-derived daily total energies to simulate monthly mean, minimum, and maximum 5-h averaged peak solar radiation intensities.

  • This model can be used to assess if SODIS technology would be applicable anywhere in the world.

Field measurements were made in Haiti during January 2001 to evaluate the model and test SODIS efficacy as a point-of-use treatment option.

  • Using the total energy from a measured solar radiation intensity profile, the model recreated the intensity profile with 99% agreement.

NASA satellite data were then used to simulate the mean, minimum, and maximum 5-h averaged peak intensities for Haiti in January, which were within 98.5%, 62.5%, and 86.0% agreement with the measured values, respectively.

Additional model simulations suggest that SODIS should be effective year-round in Haiti. Actual SODIS efficacy in January was tested by the inactivation of total coliform, E. coli, and H2S-producing bacteria. Exposure period proved critical.

  • One-day exposure achieved complete bacterial inactivation 52% of the time, while a 2-day exposure period achieved complete microbial inactivation 100% of the time.
  • A practical way of providing people with cold water every morning that has undergone a 2-day exposure would be to rotate three groups of bottles every morning, so two groups are out in the sun and one is being used for consumption.

Solar Water Disinfection (SODIS)–destined for worldwide use?[20][edit]

Link to full text:

Abstract: Last year's publication of Rob Reed's article 'Sunshine and fresh air: a practical approach to combating water disease' provoked sustained reader interest in what seems such a simple solution to a major problem. Here we can publish the results of extensive field and lab tests.

  • The ratio between exposed surface area and exposed water volume greatly influences temperature development

Chemical Solar Disinfection[edit]

Enhancement of solar inactivation of Escherichia coli by titanium photocatalytic oxidation[21][edit]

Link to full text:

Methods and Results: 

  • Cells of Escherichia coli were used as the microbiological indicator to study the possibility of improving the efficiency of solar water disinfection using titanium dioxide (TiO2) as a photooxidizing semi-conductor.
    • TiO2 was used either as a suspended powder or in an immobilized form.
      • Both applications improved the efficiency of solar disinfection.
    • TiO2 in suspension was more effective than the immobilized form, producing enhancement factors of 1•62 and 1•34, respectively.
  • Higher TiO2 concentrations reduced the efficiency. D
  • Conclusions:
    • The use of TiO2 greatly improved this efficiency.
    • The effect of TiO2 was mainly concentration-dependent, giving maximum efficiency at 1 mg ml−1.
      • The presence of DMSO and Cys removed the TiO2-induced enhancement, indicating that OH- may be involved in the process of cell killing.

Significance and Impact of the Study:

  • The efficiency of solar disinfection is limited and time-consuming and needs to be improved.
  • The use of a semi-conductor is promising as it reduces the time of exposure and therefore increases the efficiency of solar disinfection.

A Complete Review[edit]

An overview of water disinfection in developing countries and the potential for solar thermal water pasteurization[22][edit]

http://www.osti.gov/scitech/biblio/567490 This study originated within the Solar Buildings Program at the U.S. Department of Energy. Its goal is to assess the potential for solar thermal water disinfection in developing countries. In order to assess solar thermal potential, the alternatives must be clearly understood and compared. The objectives of the study are to:

  • 1. characterize the developing world disinfection needs and market
  • 2. identify competing technologies, both traditional and emerging
  • 3. analyze and characterize solar thermal pasteurization
  • 4. compare technologies on cost-effectiveness and appropriateness
  • 5. identify research opportunities.

Natural consequences of the study beyond these objectives include a broad knowledge of water disinfection problems and technologies, introduction of solar thermal pasteurization technologies to a broad audience, and general identification of disinfection opportunities for renewable technologies.

A review of solar thermal technologies[23][edit]

Abstract: The use of solar energy in recent years has reached a remarkable edge. The continuous research for an alternative power source due to the perceived scarcity of fuel fossils is its driving force. It has become even more popular as the cost of fossil fuel continues to rise. The earth receives in just 1 h, more energy from the sun than what we consume in the whole world for 1 year. Its application was proven to be most economical, as most systems in individual uses requires but a few kilowatt of power. This paper reviews the present day solar thermal technologies. Performance analyses of existing designs (study), mathematical simulation (design) and fabrication of innovative designs with suggested improvements (development) have been discussed in this paper.

A review on solar energy use in industries[24][edit]

Abstract Presently, solar energy conversion is widely used to generate heat and produce electricity. A comparative study on the world energy consumption released by International Energy Agency (IEA) shows that in 2050, solar array installations will supply around 45% of energy demand in the world. It was found that solar thermal is getting remarkable popularity in industrial applications.

  • Solar thermal is an alternative to generate electricity, process chemicals or even space heating.
  • It can be used in food, non-metallic, textile, building, chemical or even business related industries.

On the other hand, solar electricity is wildly applied in telecommunication, agricultural, water desalination and building industry to operate lights, pumps, engines, fans, refrigerators and water heaters.

Link to full text: http://www.sciencedirect.com/science/article/pii/S1364032110004533

References[edit]

  1. Burch J.D., Thomas K. E., “Water disinfection for developing countries and potential for solar thermal pasteurization”, Solar Energy, 64(1-3), 87-97, Sept. 1998.
  2. Salih F.M., “Formulation of a mathematical model to predict solar water disinfection”, Water Research, 37(16), 3921-3927, Sept. 2003.
  3. Safapour N., Metcalf R.H., “Enhancement of Solar Water Pasteurization with Reflectors”, American Society for Microbiology, 65(2), 859-861, Feb. 1999
  4. Ciochetti D.A., Metcalf R.H., “Pasteurization of naturally contaminated water with solar energy”, American Society for Microbiology: Applied and Environmental Microbiology, 47(2), 223-228, Feb. 1984
  5. Saitoh T.S., El-Ghetany H.H., “Solar water-sterilization system with thermally-controlled flow”, Applied Energy, 64(1-4), 387-399, Sept 1999.
  6. Denkenberger D. C., Brandemuehl M. J., Pearce J. M., Zhai J., "Expanded microchannel heat exchanger: design, fabrication, and preliminary experimental test", Power and Energy, 226(4), 532-544, June 2012
  7. Duff W.S., Hodgson D.A., “A simple high efficiency solar water purification system”, Solar Energy, 79(1), 25-32, July 2005.
  8. El-Ghetany H.H., Saitoh S.T., “A pilot solar water disinfecting system: performance analysis and testing”, Solar Energy, 73(3) 261-269, Mar. 2002.
  9. Guo Z.Y., Liu X.B., Tao W.Q., Shah R.K., "Effectiveness--thermal resistance method for heat exchanger design and analysis", International Journal of Heat and Mass Transfer, 53(13-14), 2877-2884, June 2010.
  10. Mehendale S.S., Jacobi A.M., Shah R.K., "Fluid Flow and Heat Transfer at Micro- and Meso- Scales With Application to Heat Exchanger Design", Applied Mechanics Reviews, 53(7), 175-193, July 2000.
  11. Dejung S, et al., “Effect of solar water disinfection (SODIS) on model microorganisms under improved and field SODIS conditions”, Journal of Water Supply: Research & Technology-AQUA, 56(4), 245-256, Jun 2007.
  12. Davies C.M., Roser D.J., Feitz A.J., Ashbolt N.J., “Solar radiation disinfection of drinking water at temperate latitudes: Inactivation rates for an optimized reactor configuration”, Water Research, 43(3), 643-652, Feb. 2009
  13. Reed R.H., Mani S.K., Meyer V., “Solar photo-oxidative disinfection of drinking water: preliminary field observations”, Letters in Applied Microbiology, 30(6), 432-436, June 2000
  14. Nieuwoudt M.N., Mathews E.H., “A mobile solar water heater for rural housing in Southern Africa”, Building and Environment, 40(9), 1217-1234, Sept. 2005.
  15. Caslake L.F., et al., “Disinfection of Contaminated Water by Using Solar Irradiation”, American Society for Microbiology: Applied and Environmental Microbiology, 70(2), 1145-1151, Feb. 2004.
  16. Jørgensen F.A.J., Nøhr K., Sørensen H., Boisen F., “Decontamination of drinking water by direct heating in solar panels”, Journal of Applied Microbiology, 85(3) 441-447, Sept. 1998.
  17. Joyce T.M., McGuigan K.G., Elmore-Meegan M., Conroy R.M., “Inactivation of fecal bacteria in drinking water by solar heating.” American Society for Microbiology: Applied and Environmental Microbiology, 62(2), 399-402, Feb. 1996
  18. Walker D.C., Len S., Sheehan B., “Development and Evaluation of a Reflective Solar Disinfection Pouch for Treatment of Drinking Water”, American Society for Microbiology: Applied and Environmental Microbiology, 70(4), 2545-2550.
  19. Oates P.M., Shanahan P., Polz M.F., "Solar disinfection (SODIS): simulation of solar radiation for global assessment and application for point-of-use water treatment in Haiti", Water Research, 37(1), 47-54, Jan 2003.
  20. Wegelin M., Sommer B., “Solar Water Disinfection (SODIS)—destined for worldwide use?”, Waterlines, Practical Action Publishing, 16(3), 30-32, Jan. 1998.
  21. Salih F.M., “Enhancement of solar inactivation of Escherichia coli by titanium photocatalytic oxidation”, Journal of Applied Microbiology, 92(5), 920-926, May 2002.
  22. Thomas K.E., Burch, J., “An overview of water disinfection in developing countries and the potential for solar thermal water pasteurization”, Scitech Connect, Jan. 1998.
  23. Thirugnanasambandam M., Iniyan S., Goic R., “A review of solar thermal technologies”, Renewable and Sustainable Energy Reviews, 14(1), 312-322, Jan 2010.
  24. Mekhilef S., Saidur R., Safari A., "A review on solar energy use in industries", Renewable and sustainable Energy Reviews, 15(4), 1777-1790.