This video lecture from Environmental Chemistry (F.Sc. second year Chemistry) covers the process of aeration and coagulation used in the water treatment cycle for the purification of raw water from ground and surface reservoirs. Aeration is defined as passing air through water to restore the dissolved oxygen level along with other benefits such as removal of foul smelling gases and oxidation of certain organic molecules. Coagulation is the process of adding a compound which helps suspended particles to form precipitates. Common coagulants include alum and ferric salts. Find more e-learning material and educational video lectures in Urdu at maktab.pk. These videos are free to use for promotional and commercial purpose by keeping the credits to Maktab.