This presentation focus on basic types and uses of aerators used 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).