Water treatment

Silicates are used in water treatment with various functions. Many wells contain high levels of iron and manganese. Through aeration and chlorination, water is clarified and precipitates form in the pipes through hydrolysis. The problem can be resolved by adding some parts per million of water glass. A similar addition can also be made to reduce corrosion in the pipes of drinking or industrial water. Silicate forms on ferrous metals and not a molecular film that prevents corrosion.
Silicate is also used for waste water treatment. The partial neutralisation of silicate with acid salts produces an anionic sol which is extremely efficient as an aid for coagulation, and is used in combination with aluminium sulphate.