Types & use of aerators in hatchery
- 1. Presented By Kazi Faridul Hasan Session : 2013-14 Deprtment of Fisheries & Marine Science E-mail: kazifaridul&gmail.com
- 3. During the past decade, pond aeration systems have been developed which will sustain large quantities of fish and invertebrate biomass. Aerators work by increasing the area of contact between air and water. Aerators also circulate water so fish can find areas with higher oxygen Recent studies suggest that heavy aeration to provide the greatest possible production is less profitable than moderate aeration
- 4. Water aeration is the process of increasing the oxygen saturation of the water. This also helps to produce active sludge which can be used as fertilizers.
- 5. Water aerators are various devices used for aeration, or mixing air with another substance, such as soil or water. These devices are used to add oxygen to the water.
- 6. Removes tastes and odours caused due to organic gases Increases DO content & decrease CO2. oxidizes dissolved metals such as iron, hydrogen sulfide, and volatile organic chemicals. It results less wastage of feed, bottom of the ponds clean and risk free from diseases.
- 7. Natural aerators Gravity Aerators Surface aerators : Turbine Aerators Vertical Pumps Aerators : Pump sprayer Propeller-aspirator-pumps Diffused Aerators Tractor-powered aerators Electric paddlewheel Aerators
- 8. They mainly manage dissolve oxygen naturally & maintained in extensive culture ponds. Operated by – By swimming in the water. By hit the water with bamboo. By entering water through inlet which is situated 10 cm or more above to the water surface. By allow duck to swim in the water. Drive the boat into water.
- 10. Advantages : * No need electricity. * Useful for extensive aquaculture. * Low cost. Disadvantages : * Aeration does not distribute whole pond. * Aeration does not occur regularly. * Production low.
- 11. simple to construct and are reliable used in small semi-intensive shrimp farms. water is allowed to rise above, the pond/tank level and then to fall freely in the pond or tank through atmosphere Then water comes in contact with oxygen and thus aeration is done. potential energy is converted into kinetic energy
- 13. Advantages : * Low cost. * Easy to management. * Low energy needed. * Aeration occur properly. * Used in waste water treatment. Disadvantages : * Disease management poor. * Need good infrastructure.
- 14. designed for installation in lagoons, tanks with variable water level, reservoirs and general mixing applications. a propeller and deflector,which are dynamically balanced directly coupled to a stainless steel shaft. minimises any loads on the motor bearings.
- 16. Advantages : * Propeller and Deflectors minimiseze any load in motor bearings. * no need much space. Disadantages : * Used only surface level of the water. * Oxygen does not distributed through whole waterbody.
- 17. unrivalled in oxygen transfer efficiency (OTE) simple, durable and has no internal moving parts robust and uses an energy efficient motor which means it delivers the greatest amount of oxygen for the least energy consumption.
- 19. Advantages : * Cost effective. * Greatest amount of oxygen for the least energy consumption. * Simple aerator. * No internal moving parts. * Need low energy. * Low maintainance costs. Disadvantages : * Oxygen does not distributed whole pond equally. * Fish are sometime injured.
- 20. consists of a submersible, electric motor with an impeller attached to its shaft. The motor is suspended by floats, and the impeller jets water into the air to affect aeration Units for aquaculture have high speed impellers, which rotate at 1730 or 3450 rpm.
- 22. Advantages : * High aeration capacity. * Used in large waterbody. Disadvantages : * High cost. * Need much more energy.
- 23. consists of a high pressure pump that discharges water at high velocity through one or more orifices to affect aeration simplest procedure is to discharge the water directly from the pump outlet complex method is to discharge the water from small orifices in a manifold that is attached to the pump outlet sizes range from 2 to 15 kW impeller speeds are from 500 to 1000 rpm.
- 25. Advantages : * Low cost. Disadvantages : * Complex method.
- 26. an electric motor, a hollow shaft which rotates at 3450 rpm, a hollow housing inside which the rotating shaft fits a diffuser an impeller attached to the end of the rotating shaft. Air is forced down the hollow shaft by atmospheric pressure, and fine bubbles of air exit the diffuser and enter the turbulent water around the impeller.
- 28. Advantages : * Fine bubbles creat good dissolve oxygen. * High aeration capacity. Disadvantages : * Need much energy for creating high water pressure.
- 29. splashes water into the air to affect aeration consists of floats, a frame, motor, speed reduction mechanism, coupling, paddle wheel, and bearings. usually turn at 1750 rpm, but this speed is reduced so that the paddle wheel rotates at 70–120 rpm
- 31. * Simple desgin. * Greatest amount of oxygen for the least energy consumption. * No internal moving parts. * Need low electicity. * Low maintainance costs. Disadvantages : * Oxygen does not distributed whole pond equally. * Fish are sometime injured by aerators wheel.
- 32. use a low pressure, high volume air blower to provide air to diffusers positioned on the pond bottom or suspended in the water Diffused-air systems that release fine bubbles usually are more efficient than those that discharge coarse bubbles more efficient in deep ponds than in shallow ponds. high efficiency for transferring oxygen from air bubbles to water
- 34. Advantages : * Low pressure, high volume air blower. * Fine bubbles released with high DO. * High efficiency transfaring airation. * Uniform aeration & mixing.
- 35. used for emergency aeration in larger ponds. Such aerators are driven by the power-take-off (PTO) of farm tractors :they are large & can qickly raise DO concentration, they are mobile and can be easily moved from pond to pond, and they do not require an electrical service they require a large tractor to power each unit less efficient than electric aerators. Therefore, the use of tractor-powered aerators is rapidly diminishing.
- 37. Advantages : * Easily moveable. * Rapid aeration in a certain time. Using ocassionally. Disadvantages : * Not used regularly. * Need more energy.
- 38. 4 to 12 feet long with paddles of triangular cross section and a total drum diameter of about 28 to 36 inches speed is usually 80 to 90 rpm with a paddle depth of about 4 inches, enough to load the motor The correct paddle depth can be determined in the field as the depth needed to draw the rated amperes of the motor Motor sizes range from 1/2 hp to 19 hp and larger
- 40. Advantages : * Rapid aeration. * Cost effective. Disadvantages : * Need electricity. * Need proper management. * Sometime need a good infrastracture..
- 41. increase fish and shrimp production Mobile aerators should be positioned in the end of the pond where DO is highest & fish will be there For emergency aeration, an aerator that discharges water over a large area. Where fish will find the oxygenated water Four paddle wheel or propeller-aspirator- pump aerators are installed in a square or rectamgular pond.
- 42. southern US suggests that at feeding rates below 30 kg ha−1 day−1, aeration usually will not be necessary (catfish) between 30 and 50 kg ha−1 day−1, emergency aeration must be applied low DO concentrations will cause stress or mortality in fish. In this range of feeding rates, an annual production of 3000–4500 kg ha−1 of catfish is normal.
- 43. using nightly aeration (midnight to dawn) with aerators controlled by timers. At identical stocking and feeding rates, better feed conversion ratio (FCR) and greater production of catfish was achieved in ponds with nightly aeration (4813 kg ha−1; FCR=1.32) than in ponds where aeration was used only on an emergency basis (3657 kg ha−1; FCR=1.75).