Biofilter in aquaponics

Aquaponics is a combination of aquaculture (fish farming) and hydroponics (horticulture). In this concept, the fish faeces and excreted ammonia are partially transformed into soluble nutrients which then are available for plants. Wastewater from aquaculture is filtrated by plants and return to the fish tank in a loop cycle. This strongly reduces the use of water and increases the economic efficiency with an additional production of plant, e.g. vegetables. From the hydroponics view, this combination allows important decreases in chemical nutrients use for plant grow.
A central part of this system is the biofilter. The microorganisms that colonize it are essential to process the fish waste into soluble nutrients easily assimilated by plants. During this process, nitrifying bacteria convert free ammonia into nitrite and then nitrate. The first objective of this research will concern the identification and isolation of the main microorganism species involved by the dilution plating and metagenomics technics. The optimal conditions to process the fish waste will be determined for such microorganism. The efficiency of nitrite and nitrate production by these micro-organisms will be tested in different conditions (T°, pH, O2, water flow, support, etc..) in vitro at the lab scale and in aquaponics prototypes.