The possibility of application of agglomerate elastomers (EPP) as media for biological bed in aquaculture

Abstract

The aim of the study was to determine the possibility of experimental media (agglomerate elastomers EPP) application as biological media bed, which serves the purpose of water purification in recirculating aquaculture systems (RAS). RAS enables mass-production of fish in small volume of water in a limited area. This involves the possibility of multiple usage of water during culture. However, for that purpose of maintaining proper physico-chemical parameters, water purification from products of metabolism, especially toxic nitrogen compounds, is required. One of the simplest and most effective ways to achieve it is combining application of two types of water filtration: mechanical and biological. It is needed to study new media for biological bed with proper filling is able to purify water from toxic nitrogen compounds. K E Y W O R D Sbiological bed, carp, EPP, recirculating aquaculture systems (RAS)

Comparison of Different Biofilter Media During Biological Bed Maturation Using Common Carp as a Biogen Donor

“…The first group oxidizes ammonia to nitrites and the other group oxidizes the formed nitrites to nitrates [6,7,[43][44][45]. By analysing the concentration of particular forms of nitrogen in the water used during the commissioning of breeding facilities, it is possible to observe individual stages of nitrification and thus determine whether the biological filter has gained functionality [18,45]. The unpredictability of the maturation process was shown in an experiment carried out by Pulkkinen et al [46] illustrating the effect of the type of biological filter used (fixed and moving bed bioreactors) on nitrification in recirculating aquaculture systems.…”

“…The experiment using fish as a source of compounds needed in the nitrification process allowed observation of the work of the biological filter in conditions simulating real fish breeding [18]. Research carried out in this way is very important to properly carry out the maturation process of the biological filter and obtain a filter adapted to the given conditions in RAS systems.…”

“…The experiment was conducted in four identical semi-open RAS systems with 625 dm 3 volumes each (daily refill-150 dm 3 ) modelled on devices used by Sikora et al [18]. Three types of biological filter fillings were examined: -Polypropylene aggregate (PPA) (active surface area 300-500 m 2 /m 3 -manufacturer's data) ( Figure 1A).…”

“…Ammonium nitrogen in its dissociated form is relatively non-toxic, whereas the undissociated form is highly toxic [8,9,[11][12][13][14][15][16][17]. For this reason, it must be controlled [17] and removed from the system or oxidised to a less toxic nitrogen form [8,18]. Ammonia levels in RAS systems are controlled by nitrification [17].…”

“…Analysis of the nitrification process gives the information if the biofilter is matured. In RAS equipped with such a biofilter, the level of ammonium and nitrite concentrations are low and stable [18]. It is especially important for finfish species, which are sensitive to toxic nitrogen compounds, like salmonids [4,6,7,11,12].…”