According to United Nations’ statistics and estimations, there are more than a billion people in the world do not have access to safe drinking water, resulting over 1.8 million of deaths annually.

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.