Water treatment is any process that improves the quality of water to make it more acceptable for a specific end-use. The end application may be drinking, industrial water supply, irrigation, water recreation or many other uses.
Water treatment has special relevance as worldwide water demand is constantly under pressure due to the increasing world population and pollution.
Technologies used for water treatment may be
- Chemical: aeration & disinfection
- Physical: dissolved air floatation, filteration & sedimentation
- Biological: slow sand filteration, and
- Physio-chemical: coagulation, flocculation
Disinfection is used for controlling algae and microbial growth.
Objective of aeration is to remove dissolved iron when present with small amounts relatively of manganese.
Dissolved air floation removes suspended solids.
To remove particles either by passage through a sand bed that can be washed and reused or by passage through a purpose designed filter that may be washable is known as filteration.
Removal of suspended solids trapped in the floc is called solid separation by sedimentation.
Using a biofilm to metabolize organice matter is slow sand filteration.
Coagulation is used to form more robust flocs & improve coagulation. Primary Coagulant are ferric chloride , ferric sulfate, or alum. Flocculation is used in conjunction with coagulation.
Water treatment is basically a "impurity treatment". However, treatment needs for one system may not be suitable for another. For an example, pH correction in cooling water is near to neutral range; whereas, for boilers it is recommended on higher side. Thus, water treatment is a vast field.
