Application as Flocculant for Water Treatment

Wastewater contains solid particles with a wide variety of shapes, sizes, densities, etc. Specific properties of these particles affect their behavior in liquid phases, and thus their removal capabihties. Many chemical and microbiological contaminants found in wastewater are adsorbed by, or incorporated into, these solid particles. Thus, essential for purification and recycling of both wastewater and industrial effluents, is the removal of these solid particles. Flocculation is a technique where polymers are involved in a solid-liquid separation by an aggregation process of colloidal particles [56]. Both synthetic and natural polymers have been utihzed for flocculation. 

The materials being used as flocculating agents can be broadly divided into two categories, inorganic and organic. The organic flocculants include 

1 Bridging Mechanism - The Theory behind Nonionic Flocculants 

Singh s easy approachability model [60-65] explains the superiority of grafted polysaccharides over other types of flocculants. This model states that the dangling branches of polyacrylamide or cationic moiety have easy approach-ability when they are grafted onto the rigid polysaccharide backbone. 

Furthermore, the more there is of the branched base of the polysaccharide, the greater the opportunity the grafted (onto polysaccharide backbone) poly-acrylamide/cationic moiety chain will have to form an aggregate of the contaminants. Thus, if the grafted moiety is loaded onto the most hyperbranched polysaccharides, it will have easier accessibility to form aggregates of the contaminants, providing the best flocculation characteristics. 

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