NATURAL TREATMENT OF POLLUTANTS IN WATER:Pollutants that can be oxidized by bacteria in the presence of free dissolved oxygen can be aerobically converted to CO2 and H2O. These pollutants, such as domestic sewage and many readily biodegradable industrial wastes, can be destroyed in accordance with the oxygen sag equations presented above, if oxygen is naturally reinjected into the water through surface turbulence.
ARTIFICIAL TREATMENT OF POLLUTANTS IN WATER:Dissolved oxygen can be added artificially to a body of water by aerating the surface with floating aerators. This can provide the oxygen necessary for natural bacterial decomposition of pollutants and for the propagation of aquatic life, can also prevent lake or river stratification minimizing the return of settled pollutants to the water surface. Air diffusers and blowers can also be used for artificially aerating water.