Developing knowledge and capacity in water and sanitation
The removal of organic and inorganic material from raw water is essential before it can be disinfected for human consumption. In a water treatment works, this clarification stage is normally achieved by the application of chemical coagulants which change the water from a liquid to a semi-solid state. This is usually followed by flocculation, the process of gentle and continuous stirring of coagulated water, which encourages the formation of 'flocs' through the aggregation of the minute particles present in the water. Flocs can be easily removed by settling or filtration. For many communities in developing countries, however, the use of coagulation, flocculation and sedimentation is inappropriate because of the high cost and low availability of chemical coagulants, such as aluminium sulphate and ferric salts.
This Technical Brief gives an overview of the application of an indigenous, naturally derived coagulant, namely seed material from the multi-purpose tree Moringa oleifera Lam. (M.oleifera) which offers an alternative solution to the use of expensive chemical coagulants.