BIOSHELL project “Development of an innovative biological filter to apply in aquaculture based on a sustainable filling of mussel shell” has been carried out at a laboratory scale in the ANFACO-CECOPESCA facilities and at a pilot scale in the Grupo Tres Mares plant in Lires (Cee) with the objective of revalorizing the mussel shells as a filling material in biofilters for the depuration of aquaculture waters. The objective is to promote, in the concept of a circular economy, new applications for such an abundant waste in Galicia. In this project has participated the Institute of Sustainable Processes of the University of Valladolid in colaboration with the Fundación Biodiversidad from the Ministerio para la Transición Ecológica, through the Pleamar Program, cofunded by the FEMP.
The idea of the Bioshell projects arises with the objective of solving the problem of mitigate the ammoniacal nitrogen and organic matter in the pisciculture recirculation waters through a low cost system using mussel shells instead of plastic bioballs as filling and support matterial for the bacterial growing. During the project, the entire 2019 and the first month of 2020, ANFACO-CECOPESCA has worked with laboratory systems to compare the shell filling systems against the conventional ones, with a very promising results as the shells allowed equal or better eliminations than the bioballs in terms of ammoniacal nitrogen, the most problematic compound in the facilities for the fish survival, under work conditions of closed circuit. Besides achieving the practically complete elimination of ammonium in barely a week after the beginning of the process, the shells allowed more stability in the operation as they do not need external pH control.
With the laboratory results and due to the low nitrate elimination in the first phase, the Institute of Sustainable Processes designed a biofilter at a pilot scale in order to improve desnitrification with a variation in the design regarding the laboratory setup and to improve the water distribution systems to avoid preferential paths in the process that decrease its efficiency. Once the pilot system was built, it was operated in the Grupo Tres Mares plant in Lires with real water.
Although the results pointed a clear environmental and technical viability, the process will be evaluated during long time periods at an industrial scale to validate the technology and evaluate its economic viability.
The aquaculture sector is in vogue and growths in an exponential way in the last few years, and it is necessary to think in sustainable ways to maintain this development through innovative processes that allow improving the environmental management of the plants and at the same time being affordable by the aquaculture facilities. Bioshell project results are promising enough to think in improvements in sustainable and low cost recirculation systems in line with the circular economy principles.
