Anup Ghimire, Rock Face Limited
particles: suspended in drinking
Colloids are minerals such as silt, clays,
silica, hydroxides and metallic salts and
organic particles such as humic and fluvic
acids, colour and surfactants.
Affinity for water
soap, starch, proteins and detergents
metal oxides and clay
and flocculation remove colour
and particulate matter including protozoa,
viruses, bacteria and iron, manganese,
tastes and odours from water
Coagulation involves the neutralization of
suspended solids by adding coagulants in the water
which forms micro flocs after sticking together
process is faster and involves
electrical charges of the particles and
facilitates floc formation.
is a slow and gentle mixing
The destabilized particles are agglomerated
to form large visible flocs
flocs and visible flocs are produced at
the flocculation stage when micro flocs are
allowed to mix slowly. Pin flocs are filtered
from water by sedimentation. Coagulants
can be mineral or organic.
salts and aluminium salts are mineral
coagulants used in water treatment and
polyamines, polydadmac, dicyandiamide
resins, and melamine-formaldehyde resins
are organic coagulants.