| Aquaculture |
|
° Home ° News ° Aquaculture Engineering ° References ° Where to find us ? ° Contact ° Jobs, placements |
| Marine farms, hatcheries |
|
° Marine farms ° Marine hatcheries |
| Shellfish purification |
|
° Shellfish purification units ° Stations capacities |
| Packaging |
|
° Packaging units |
| Public aquariums |
|
° Public and private aquarium ° Museography |
| Quality and Agreement Approach |
|
° Sanitary accreditation ° Control and certification |
| Environmental Impact study |
|
° Reglementation and Environmental Impact Studies ° Environmental Impact Study |
Waterfalls
| Principles : Natural or artificial waterfalls allow significant gaseous exchange as they combine an increase in the surface exposed to the air with the strong mixing and turbulence caused by the fall. There are many different types of water-fall: |
 |
1/ Large waterfall A drop greater than 1m 40 with a deep receptiOn pit in which an air emulsion (white water) is created. |
 |
2/ Waterfall with obstacle Less than 1m 40 drop, arranged as a straightforward fall, which breaks on an artificial obstacle placed in the receiving tank. |
 |
3/ Waterfall with graded falls Subdivided into several successive falls which reduces the speed of the fall and allows an increase in the contact time with the atmosphere. |
 |
4/ Waterfall with graded drop and jet. Equally divided into several levels, several vertically positioned jets optimise flow and air/water exchange. |
 |
Technical characteristics : At the top and on the sides of the waterfall, the spreading of the surface into a thin layer increases contact surface over the time of falling, due to accelerated vertical movement the speed in m/s at the base of the waterfall reaches the value V = v2*g*h (h being the height of the waterfall expressed in meters and g = 9.81 m/s which is the acceleration due to gravity) For a waterfall of 1m in height, the speed is around 4m/s at the base which leaves little time for gaseous exchange. Efficiency : The time of water freefall being brief, the dissolution of the gas is generally incomplete (in relation to the state of saturation). The prolonging of the fail time by various means increases the efficiency of gravity aerators. Waterfalls which are overfed with strong flows lose in efficiency. |
|
To contact AQUALOG |
.jpg) |
Jets crossing a geasous atmosphere
 |
Principle : Like the waterfalls, the jets are fed either by pumps or by a natural slope. Many nozzles arranged in a line une either vertically or diagonally and fed by powerful jets spread out over the surface creating emulsions. |
Column of superposed jets
 |
Use: Elimination of carbon dioxide and equilibration of quantities of nitrogen and oxygen as a function of air saturation. |
|
To contact AQUALOG |
|
Filled Columns
 |
Principle: The column are filled with flakes (morsels of cut PVC, morsels of wire mesh, hollow plastic spheres etc.). Arranged vertically, they slow the descent of the water, assuring gaseous exchange from the effects of turbulence. The vent-holes arranged at each side allow simultaneous oxygenation and nitrogen elimination of oversaturated water. The filling objects are inert materials so as not to affect the quality of the water. The filled columns are mainly used in closed circuits to re-equilibrate the water with the gas of the atmosphere. The height of the columns is around 1m. |
 |
Technical characteristics : The diameter depends on the flow to be treated, for example for 1 m3/mn, a column with a 1m2 section is required. Efficiency : These columns are not really appropriate for intensive ongrowing due to the volume of water to be treated. It is advisable to place some vent-holes in the internal walls to achieve equilibrium.  |
Micro vortex aerator
 |
Principle : Water floWing by gravity through the staggered structure of the aerator creates a multitude of micro-vortices resulting in the optimum transfer of oxygen from the air into the liquid. Flow: 4to 100 m3/h. Power: 0.5 to 4 kW. OSOI 5.5 kg-O2/ absorbed kWh |
 |
The Micro Vortex aerator is: * completely adaptable : the area of the structure can be adapted to the quantity and quality of the water to be aerated. * easy to install: it can be either on a float or fixed. * multi usage : it allows - Aeration of tanks - nitrogen stripping and re-equilibrating the ratio of N2/02 in the air. |
|
To contact AQUALOG |
|
Aqualog
Bouée Borha
Corniche du Bois Sacré
Marépolis Est
83500 La Seyne sur Mer
Tél. : 04 94 10 26 26
Fax : 04 94 10 26 30
