Foam fractionation efficiency in particulate matter and heterotrophic bacteria removal from a recirculating seabass (Dicentrarchus labrax) system

In recirculating aquaculture systems (RAS), particulate matter and bacterial communities management are required to maintain water quality. Foam fractionation is a water treatment technology that can be easily applied to water reuse systems to remove bacteria and suspended solids. This study investigated the efficiency of foam fractionation in removing particulate matter and heterotrophic bacteria in a closed recirculating seabass (Dicentrarchus. labrax) system. This system consisted of 10 rearing tanks, a skimmer acting as the foam separation system (SKIM®), a biofilter unit, and an UV unit. The efficiency of SKIM was analyzed for different foam fractionation operation times (5′on/5′off, 15′on/15′off and 30′on/30′off) and for different sizes of particulate matter (>60 μm, 60-8 μm, 8-1.2 μm, and 1.2-0.22 μm). The removal of particulate matter was influenced by different particle sizes with higher removal percentages for the >60 μm and 1.2-0.22 μm categories of 96.8 and 100%, respectively. Nevertheless, these categories represented the lower percentage of total solid compositions in the RAS water studied (>60 μm = 7.14 ± 2.78%, and 1.2-0.22 μm = 18.27 ± 2.50%). The removal of heterotrophic bacteria did not correlate with the operation time or particle size and SKIM removal percentages ranged between 32 and 88%.