Abstract:
The natural purification of streams is a very important phenomena for the cleanliness of the river and associated environment. The most critical parameter on which the pollution of the water body is based is the dissolved oxygen in the water which is the effect of BOD- The delicate balance is maintained between the dissolved oxygen of water and the sources and the sinks of dissolved oxygen. The present paper gives an account of natural purificatirn capacity of rivers. A concise account of the various studies in this regard in the major rivers of the country have been presented. The various sources and sinks of dissolved oxygen and the BOD have been ennumerated and it has been advocated that the self purifying abilities of the streams should be properly evaluated and exploited to the fullest so that the pollution control cost could be minimised. The example of river Ganga and river Yamuna have been cited.
