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Solar Water Disinfection System with Solar heating

Similar to Solar Water Disinfection System (SODIS) initiated by Professor Aftim Acra, Solar Water Disinfection System with solar heating is a water purification system at household level based on solar radiations with additional use of solar heating. Since SODIS is only ideal to disinfect small quantities of micro-biologically contaminated water of low turbidity, a solar heated distillation process is combined with the conventional SODIS. Contaminated water is first distilled by using a solar heated low-temperature distillation system to remove any non-volatile solid impurities such as salts, sediment and heavy metals. However, the distilled water is not drinkable since the water may still contain bacteria, viruses and in some cases protozoans. To address this problem, the distilled water is then contained in clean and transparent PET bottles or glass bottles and are exposed to the sun light for a certain amount time (depending on the intensity of the sun light) allowing the radiations to deactivate any waterborne pathogens^[1] in the contaminated water. Solar water disinfection is an effective way to purify drinking water as it is recommended by World Health Organization^[2]. It uses only solar energy and can be built using only recycling materials, thus, the system is environmentally sustainable.

Theory

The principle of SODIS is based on Ultraviolet water treatment . It uses two components of the sunlight for the water disinfection process :Ultraviolet radiationand infrared radiation. UV-A radiation(wavelength 320-400 nm) interacts with the DNA, nucleic acids and enzymes of the organic cell, destroys the cell molecular structures which leads to cell deaths. UV-A radiation also reacts with oxygen dissolved in the water producing highly reactive forms of oxygen (oxygen free radicals and Hydrogen peroxide], that can help the germicidal process. Infrared radiation is a long-wave form of sun radiation, it can be felt as heat, as it is responsible for raising the fluid temperature. Studies had proven that 99.9%^[3] of microorganisms within water are eliminated if the water is heat heated to 50-60°C for one hour.

UV-A radiation directly interacts with the DNA, nucleic acids and enzymes of the living cells, changes the molecular structure and leads to cell death. UV radiation also reacts with oxygen dissolved in the water and produces highly reactive forms of oxygen (oxygen free radicals and hydrogen peroxides). These reactive molecules also interfere with cell structures and kill the pathogens.

for anti bacterial propos

has a germicidal effect.

The second component, infrared radiation, raises the water temperature and is known as

Contaminated water is fi lled into transparent plastic bottles and exposed to full sunlight for six hours. During the exposure to the sun the pathogens are destroyed. If cloudyness is greater than 50% , the plastic bottles need to be exposed for 2 consecutive days in order to produce water safe for consumption. However, if water temperatures exceed 50°C, one hour of exposure is suffi cient to obtain safe drinking water. The treatment effi ciency can be improved if the plastic bottles are exposed on sunlight refl ecting surfaces such as aluminium- or corrugated iron sheets.

Solar Water Disinfection System Construction

Figures

Bottle Selection

• Transparent, smooth surface PET bottle
• Concerns about PET bottle safety under UV light

Turbid Water Filtration System

Using solar heat evaporation ( Water Distillation)

Turbid Water Filtration System Construction

more Figures

References

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