Integrated marine aquaculture with halophytes

DBU Project AZ 27708: Biological wastewater treatment in land-based marine circulation systems through the integrated culture of halophytes

The goal of this project is the biological wastewater treatment in marine recirculating aquaculture systems by an integrated culture of salt-tolerant plants (halophytes) in constructed wetlands. Although, the water renewal rate of the oceanloop is less than 1% of the system volume per day, there is ecological as well as economic interest in recycling the wastewater. This can be done using constructed wetlands.

Constructed wetlands are already an interesting alternative to treat domestic sewage, especially in remote areas, and are also used to treat waste water of freshwater aquaculture systems. The water treatment in constructed wetands is an interaction of different processes; such as mechanical purification by the substrate; assimilation, conversion or removal of organic and inorganic matter by bacteria; nutrient assimilation in the scope of plant growth and adsorption or precipitation reactions on particles and roots.

The application of constructed wetlands for marine aquaculture is hardly investigated. Halophytes are an interesting supplement to the production of seafish. Many species are already used in some regions of Europe as a foodstuff and have a interesting market potential, regarding their nutritional value as well as taste.

The project works on the basic information and requirements to combine the production of halophytes in constructed wetlands with the land-based production of seafish. If the project is successful, we aim to establish a commercial pilot system.

The long-term goal is to completely recycle the waste water of land-based fish farms and generate a marketable product at the same time. The diversification of the product portfolio will improve the profitability and sustainability of recirculating aquaculture systems. The halophytes can be sold as food for human consumption or as mineral-rich feed plants.