Solar water disinfection
Solar water disinfection is a type of water purification system that uses solar energy in order to make contaminated water safe to drink. This is done by eliminating contagious biological organisms such as bacteria, viruses, protozoa and worms. This process can only be taken place on biological agents non-biological agents such as toxic chemicals or heavy metals disinfection may not make all kinds of water safe to drink. Therefore additional steps away from disinfection may be necessary to make water clean to drink such as the process of flocculation. The two main ways of solar water disinfection are:
1) Heat. Solar thermal water disinfection.
2) UV. Solar ultraviolet water disinfection.
* Solar thermal water disinfection uses heat from the sun to heat water at high temperature of about 100oC for a short period of time. Water heated to temperatures below 100C is generally referred to as pasteurized water.
* Solar ultraviolet water disinfection, known as SODIS, is a method of disinfecting water using only sunlight and plastic bottles (PET bottles). This is an effective and very cheap method. SODIS is usually applied at the household level. Due to the fact that it is an affective and cheap method it is applied in numerous developing countries.
Within Africa only 46% of the people have access to fairly safe drinking water, more than two million people die from water based diseases per year. SODIS is an effective method for treating water in areas where fuel is unavailable or expensive. SODIS is a more economical and environmentally friendly option therefore could even be used where fuel is available. The application of SODIS is limited if there aren’t enough clean and new PET bottles or if the water is highly turbid. In fact, if the water is highly turbid, SODIS cannot be used alone; additional filtering is then necessary. This is the reason why flocculation is promising as substances used for it such as Alum is...
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