about environmental engineering

2. THEORY OF OXIDATION PONDS
 An oxidation pond is an artificial pond of controlled
design, in which sewage can be retained for sufficient time
to satisfy the B.O.D.
 The change in the character of the sewage and waste matter
occur due to the dual action of aerobic bacteria and the
algae.
 The aerobic bacteria use oxygen of the atmosphere,
whereas the algae is active in the sunlight.
 This combined action may be called ‘Bacterial-algae-
Symbiosis’
 When the aerobic bacteria and the algae live and work
together for their mutual benefit.

3.  Due to the dual process of photosynthesis acting on
the sewage , it breaks up the carbon dioxide produced
during the carbon cycle from the carbohydrates
present in the sewage .
 This carbon is used in the further production of the
carbohydrates and the release of oxygen into the water.
 Oxidation ponds are capable of treating successfully
both the raw or settled sewage.
 But usually in practice settled sewage is treated by
these ponds.

4.  The loading of sewage maybe between 150 to 320
kg/day/hectare with good algae(chlorella) seeding at
5days B.O.D.
 But in colder countries the efficiency are very poor and
the maximum loading are about 1/4th the above
loading.