Aluminum and Iron are two main coagulants applied to water treatment

When referring to coagulants, positive ions with high valence are preferred. Generally aluminium and iron are applied, aluminium as Al2(SO4)3- (aluin) and iron as either FeCl3 or Fe2(SO4)3-. One can also apply the relatively cheap form FeSO4, on condition that it will be oxidised to Fe3+ during aeration.
Coagulation is very dependent on the doses of coagulants, the pH and colloid concentrations. To adjust pH levels Ca(OH)2 is applied as co-flocculent. Doses usually vary between 10 and 90 mg Fe3+/ L, but when salts are present a higher dose needs to be applied.

Read more: http://www.lenntech.com/products/chemicals/water-treatment-chemicals.htm#Coagulants#ixzz2mVtpkppM

 

PREVIOUS: Advantages of HQ Membrane Chemicals

NEXT: