Flocculation is the process in which colloids aggregate or come together to form larger
particles called flocs by the addition of a chemical called flocculant.
Typical flocculants include Alum (Hydrated Aluminium Sulphate) and Ferrix (Commercial Iron
Salts) because they work well with high turbidity fluid mixtures. Almost all colloids have
negatively charged surfaces which means that positive ions or charged particles in the
water will attract to the colloid surface forming a first layer. A diffuse layer made up of a mix
of positive and negative ions will then surround the first, forming what is called a double
layer area. This double layer area provides a repulsive force that prevents two colloids from
sticking to each other. Once the flocculant is added, it adheres to the surfaces of the
particles, compressing the double layer and allowing the colloids to stick to each other and
form flocs. These flocs are now heavy enough to settle to the bottom by gravity