Many coagulants are widely used in conventional water
treatment processes based on their chemical characteristics. These coagulants
are classified into inorganic, synthetic organic polymers and natural
coagulants. Coagulation is the most essential process in the treatment of both
turbid surface and industrial wastewaters. Coagulationflocculation is one ofthe most important physicochemical treatment steps in wastewater treatment toreduce the turbidity of wastewater. Due to the lack of proper water treatment
systems in these rural or under developed communities the best immediate option
is to use simple and relatively cost effective point of use technologies such
as coagulation.
Chromium(VI) is highly toxic and soluble in water and it is a
strongoxidizing agent that causes severe damage to cell membranes. The mostcommonly used primary chemical coagulants, namely alum (AlCl3), ferric chloride(FeCl3) and polyaluminium chloride (PAC). The disadvantages associated with
these coagulants such as ineffectiveness in low temperature water relatively
high procurement cost, detrimental effects on human health, production of large
sludge volumes and the fact that they significantly affect pH of treated water.
There is strong evidence linking aluminium based coagulants to the development
of Alzhemier’s disease in human beings.
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