Mitigating off-flavour compounds geosmin and 2-methylisoborneol by applying capacitive deionization and nanotechnology in RAS

Fin fish aquaculture is currently experiencing significant pressure to improve its environmental sustainability to allow it to continue its rapid growth. As a result of these pressures, the industry is increasingly adopting land-based recirculating aquaculture systems (RAS), where water usage is minimised and the risks of release of inbred strains with associated diseases into wild populations is eliminated as are the associated nutrients that cause local environmental problems.

Perhaps the biggest barrier to this industry migration to RAS, is the development of off-taste in these systems caused by the accumulation of geosmin and other chemicals to which the human palate is particularly sensitive. These chemicals are produced by microbial communities in biofilms and in the water column.

The current solution to this off-taste development is to purge fasting fish for up to 14 days in clean water with associated significant weight and value loss. Traditional antimicrobial techniques to combat the off-taste micro-organisms are unavailable in RAS due to their negative impact on biofilters as well as their toxic effects on the growing fish. This consortium consists of a strong combination of University, RTD and Industrial partners from Denmark, Sweden and Norway with expertise in RAS systems, biofilm development and microbial off-flavour chemical production, as well as nanomaterials and water quality control.

The CDI-NANO-RAS project aims at testing novel technologies for the control of off chemicals in RAS as well as purging systems. We hypothesise that the combined use of novel capacitive deionization (CDI) technology and photocatalytic nanotechnological surface coatings can provide an energetically efficient method for the control of off-taste development in RAS as well as in reducing the duration and water usage in pre-harvest purging.  The overall aim is to develop cost effective solutions applicable for the modern RAS industry.