In a large number of underdeveloped and developing countries, there is scarcity of safe drinking water. People are forced to drink contaminated water infested with disease causing bacteria, which causes many water born diseases. Various methods like chlorination, ozonation, boiling and irradiation by UV light are used to purify water. However these methods require chemicals, fuel, and electricity, which are not available in remote undeveloped areas. A "domestic water purification device" is designed on photocatalytic disinfection of water using non-toxic, reusable photocatalyst and solar light. The device does not require electricity, chemical and high pressure tap water.

SALIENT FEATURES

• Works on solar light. (Even diffused sunlight on a cloudy day is sufficient.)
• Does not require electricity, chemical and high pressure tap water.
• Very effective as it kill bacteria > 99.99 % (4log scale).
• Almost maintenance free except occasional cleaning of the glass cover, prefilter and tray.

APPLICATION

The device is meant for purification of drinking water with respect to suspended particles, dissolved organics and bacteria. The device purifies water in batch mode. The device of 60 cm x 65 cm x 10 cm size can disinfect ~ 15 liters of drinking water daily using solar light.

INTRODUCTION
In a large number of underdeveloped and developing countries, there is scarcity of safe drinking water. People are forced to drink contaminated water infested with disease causing bacteria, which causes many water born diseases. Various methods like chlorination, ozonation, boiling and irradiation by UV light are used to purify water. However these methods require chemicals, fuel, and electricity, which are not available in remote undeveloped areas. A "domestic water purification device" is designed on photocatalytic disinfection of water using non-toxic, reusable photocatalyst and solar light. The device does not require electricity, chemical and high pressure tap water.

WORKING PRINCIPLE

The device works on the principle of photocatalytic disinfection of water stored over the photocatalyst using solar light. Water is passed through a gravity flow prefilter to remove suspended particles and dissolved organics. Filtered water is exposed to solar light for disinfection using a photocatalyst coated tray. When the photocatalyst is exposed to UV from solar light, electrons (e-) and holes (h+) are generated on the catalyst surface, which react with water to give H. and OH. radicals. Bacteria present in water are killed via oxidation by OH. radicals, which are strong oxidizing agents.

SALIENT FEATURES

• Works on solar light. (Even diffused sunlight on a cloudy day is sufficient)
• Does not require electricity, chemical and high pressure tap water.
• Very effective as it kill bacteria > 99.99 % (4log scale).
• Almost maintenance free except occasional cleaning of the glass cover, prefilter and tray.

APPLICATION

The device is meant for purification of drinking water with respect to suspended particles, dissolved organics and bacteria. The device purifies water in batch mode. The device of 60 cm x 65 cm x 10 cm size can disinfect ~ 15 liters of drinking water daily using solar light. 

RAW MATERIALS

Raw material is easily available in local market.

INFRASTRUCTURE

A small clean room is needed for preparation and coating photocatalyst on tray. Another room is needed to clean and dry trays. An oven is required for calcination. Constant source of water is needed for cleaning the trays.

MANPOWER

One chemist (1 hour daily) and one technician to observe the process and 2 skilled workers would be adequate to produce ~ 25 water purifiers per day .