Oxidation ponds

Oxidation ponds: Oxidation ponds also called lagoons or stabilization ponds, are large, shallow ponds designed to treat wastewater through the interaction of sunlight, bacteria, and algae. Algae grow using energy from the sun and carbon dioxide and inorganic compounds released by bacteria in water.

Principal & Operation:

• Raw Sewage or Primary Settled sewage is allowed to be collected in pond.
• Stabilization of organic matter is carried out by combined action of algae and other micro organism by symbiotic relationships
• Symbiotic relationships exist between algae and microorganism in the sense, algae produce oxygen while growing in the presence of sunlight and that oxygen is utilized by the micro organism
• End products of the process are CO2, ammonia and phosphate these are utilized by algae.
• Effluents of oxidation pond can be used for land irrigation

Construction details : It is a shallow earthen pond made below the ground and surrounded on all four sides by high embankment.

Design Criteria 

Organic loading:

• For hot countries: 150 -300 kg/hect/day
• For cold countries :60-90 kg/ hect/day
• Each unit may have an area 0.5 to 1 hect.
• Depth may be kept between 1 to 1.5 m
• Detention time : 20 to 30 days (varies with the local temperature)

Results: BOD removal up to — 90%

Clearing of Settled sludge- Generally once in 6 yrs

• To stimulate algae growth. Sodium nitrate may be added. It Is a plant food and oxidizing agent also.