Difference between revisions of "Aeration"
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* ammonia and hydrogen sulfide reduction (stripping) | * ammonia and hydrogen sulfide reduction (stripping) | ||
| − | Aeration is also an effective method of bacteria control. | + | Aeration is also an effective method of bacteria control. |
| + | In developing countries the common method for aeration is by splashing the water over trays or by blowing air bubbles through the water. | ||
==Suitable conditions== | ==Suitable conditions== | ||
Revision as of 23:42, 3 October 2012
Aeration is a unit process in which air and water are brought into intimate contact. This process is also referred to as aerobic treatment. The process happens naturally in the wild, for instance turbulence increases the aeration of flowing streams. In industrial processes, water flow is usually directed countercurrent to atmospheric or forced-draft air flow. Aeration ponds are also used in centralized water systems. The contact time and the ratio of air to water must be sufficient for effective removal of the unwanted gas.
Aeration as a water treatment practice is used for the following operations:
- carbon dioxide reduction (decarbonation)
- oxidation of iron and manganese found in many well waters (oxidation tower)
- ammonia and hydrogen sulfide reduction (stripping)
Aeration is also an effective method of bacteria control. In developing countries the common method for aeration is by splashing the water over trays or by blowing air bubbles through the water.
Contents
Suitable conditions
Temperature significantly affects the efficiency of air stripping processes. Therefore, these processes may not be suitable for use in colder climates. Theoretically, at 68°F the carbon dioxide content of the water can be reduced to 0.5 ppm by aeration to equilibrium conditions. This is not always practical from an economic standpoint, and reduction of carbon dioxide to 10 ppm is normally considered satisfactory.
Construction, operations and maintenance
Two general methods may be used for the aeration of water. The most common in industrial use is the water-fall aerator. Through the use of spray nozzles, the water is broken up into small droplets or a thin film to enhance countercurrent air contact.
In the air diffusion method of aeration, air is diffused into a receiving vessel containing counter-current flowing water, creating very small air bubbles. This ensures good air-water contact for "scrubbing" of undesirable gases from the water.
Reference manuals, videos, and links
- Aeration.
- Commercial aerators: Water aeration equipment.
- Rural cost functions for water supply and sanitation. OECD EAP Task Force Secretariat, 2005.
Acknowledgements
- Chapter four: Aeration. GE Power and Water.
