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Description
In aquaculture, the fixed substrate (or fixed media) is a solid, immobile support designed to promote the colonization of nitrifying bacteria and to enhance gas exchange in recirculating systems or grow-out tanks.
Main Functions
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Biofiltration
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The fixed substrate provides a large specific surface area for the growth of autotrophic bacteria (Nitrosomonas, Nitrobacter, Nitrosospira).
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These microorganisms convert toxic ammonia (NH₃/NH₄⁺) and nitrite (NO₂⁻) into less harmful nitrate (NO₃⁻).
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The support ensures stable and continuous biological purification through biofilm attachment.
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Water Degassing
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Water flowing through the substrate enhances air–water contact, enabling the removal of carbon dioxide (CO₂) and other dissolved gases (nitrogen, H₂S).
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This passive aeration helps to maintain pH balance and increase dissolved oxygen levels.
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Fixed Substrate for Biofiltration and Water Degassing in Aquaculture
Description
In aquaculture, the fixed substrate (or fixed media) is a solid, immobile support designed to promote the colonization of nitrifying bacteria and to enhance gas exchange in recirculating systems or grow-out tanks.
Main Functions
-
Biofiltration
-
The fixed substrate provides a large specific surface area for the growth of autotrophic bacteria (Nitrosomonas, Nitrobacter, Nitrosospira).
-
These microorganisms convert toxic ammonia (NH₃/NH₄⁺) and nitrite (NO₂⁻) into less harmful nitrate (NO₃⁻).
-
The support ensures stable and continuous biological purification through biofilm attachment.
-
-
Water Degassing
-
Water flowing through the substrate enhances air–water contact, enabling the removal of carbon dioxide (CO₂) and other dissolved gases (nitrogen, H₂S).
-
This passive aeration helps to maintain pH balance and increase dissolved oxygen levels.
-
€0.00
Tax included
For the biological treatment of effluent in fish farming. In practice, several biofiltration methods are used. All methods share the use of a substrate that provides a surface for bacterial colonization.
AK blocks for use in degassing columns, trickling filters, and submerged fixed-bed reactors, up to 12 m column height, excellent water distribution, and very long service life.
| Models | Reference | Name | Matérial | m2/m3 (*) |
Lenght - Width - Height (mm) (**) |
Speed max | Weight (kg/m3) |
| 1 | G0325100 | AK3-27 | PP | 125 | 2400-300-600 | 30 m3/m2/h | 25 |
| 2 | G0325200 | AK3-19 | PP | 152 | 2400-300-600 | 28 m3/m2/h | 23 |
| 3 | G0325300 | AK3-12 | PP | 240 | 2400-300-600 | 25 m3/m2/h | 31 |
| (*) specific surface | |||||||
| (**) Other sizes available on request | |||||||
Key Technical Characteristics
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Structure: rigid materials (plastic, ceramic, sintered glass, porous rock) arranged in fixed layers or blocks.
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Specific surface area: typically 100–500 m²/m³, depending on the material.
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Controlled porosity: allows efficient water flow without clogging.
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Chemical inertness: does not alter pH or release compounds.
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Easy maintenance: mechanical cleaning or backwashing possible.
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Durability: long service life, resistant to wear and temperature variations.
Typical Applications in Aquaculture
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Trickling filters or percolating biofilters.
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Degassing or denitrification towers.
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Fixed-bed bioreactors in RAS (Recirculating Aquaculture Systems).
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Pre-treatment or polishing tanks to improve water quality before discharge or reuse.
