Water everywhere not a drop to drink. We are very familiar with this term. So far, we have discussed how the anthropogenic activities degrade our environment.
Contamination of water now has reached to such a height that it is very unsafe to drink as well as cook food with such water and even water meant for washing purpose should also be taken care of.
The waste water collected from various sources should be treated so as to remove contaminants in order to be released again into their origin.
The treatment must remove pathogens, BOD materials, excessive nutrients and toxic chemicals. The drinking water standards can be categorized into:
1. Primary standard specifies maximum allowed contaminant, like organic and inorganic chemicals, radio nuclides like radon gas and micro biological contaminants levels relating to health.
2. Secondary standard is related to taste, odour and colour, corrosively and hardness and is less related to health.
The type of contaminants are, excessive sulphate for laxative effect, excessive fluoride resulting in brownish discoloring of teeth, excessive iron and manganese for bad taste and odour, due to gases like CH4, H2S, S02, etc.
The water, therefore, must be treated so that raw water becomes drinkable. The two sources of drinking water are both ground water and surface water. The main characteristics of these two sources are:
Ground Water :
1. Little suspended materials
2. Less chances of contamination
3. Less hardness
4. Chances of greater concentration of objectionable dissolved gases
Surface Water :
1. High concentration of suspended materials
2. Greater chances of pollution
3. Greater chances of hardness
4. Objectionable dissolved gas, depending on the type of water resources