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Integrated on-farm Aquaponics systems for co-production of fish, halophyte vegetables, bioactive compounds, and bioenergy

Periodic Reporting for period 1 - AQUACOMBINE (Integrated on-farm Aquaponics systems for co-production of fish, halophyte vegetables, bioactive compounds, and bioenergy)

Reporting period: 2019-10-01 to 2021-03-31

Soil salinity has been reported as a major factor to farm land degradation. About 6.7 million hectares are considered salt affected and 72 million hectare are considered sodic in EU. This is twice the area of Germany. Halophytes are plants that are salt tolerant and can grow in saline soils and/or be irrigated with seawater. Halophytes have been consumed by humans for centuries, and are still often gathered from the coastal salt marshes and inland salt pans of Europe. These species are well known for their ability to synthesize high concentration of bioactive secondary metabolites. Hence, this type of vegetables give a high potential for co-production of food and bioactive compounds especially as two third of the halophyte biomass is a non-food residue that is not utilized today.
The AQUACOMBINE project aims to demonstrate combined aquaculture and halophyte farming using the principles of circular economy, where waste and residues are utilized within the system to create both internal value and new products. Excess nutrients from the fish production will be used as fertiliser for halophyte plants and filtered through a microbial water treatment system to enable recirculation of the water back into the aquaculture tanks (Recirculating aquaculture system). This aquaponics system is very flexible and can be adapted to a wide variety of locations including rural and remote areas and outermost regions of the EU.
The project focuses on four main species of domesticated halophyte plants and subspecies; Salicornia europaea, Salicornia ramosissima, Aster tripolium, and Crithmum maritimum The overall objective is to optimise all processes needed to be able to demonstrate feasible production of fish, (recirculating aquaculture), halophyte vegetables, and conversion of halophyte residue (the non-food part of the plants) to botanical extracts and bioactive compounds for the cosmetic and functional food and feed industry as well as bioenergy and activated charcoal from residual fibres.
All the planned activities of the AQUACOMBINE project have been started during the first reporting period (M1-M18). The main focus has been in the halophyte cultivation and detailed chemical characterization of the produced biomasses as well as on development of the optimal process conditions for the bioactive compounds, protein, and lipid extractions as well as fiber residue utilization for biogas and dietary fibers for feed (xylooligosaccharides).

Continuous harvests of Salicornia europaea, Salicornia ramosissima, Aster tripolium, and Crithmum maritimum have been provided by cultivation partners including biomass samples cultivated at different salinities. Detailed chemical characterisations of all produced biomass samples have been carried out and documented according to cultivation conditions and harvesting times. Large amounts of both green biomass and mature dry biomass have been provided by demonstration and industry scale cultivation partners (Riasearch and Les Douceurs du Marais) throughout the 2020 cultivation season. The biomasses have been received at Aalborg University (the coordinator), where it has been fractionated to provide partners with biomass samples for the process optimizations.

For the optimization of fractionation and extraction processes (for the production of bioactive compounds, protein, lipids, dietary fibers, and biogas) Salicornia ramosissima was used as the main biomass. The bioactives extraction process was optimised testing different types of extraction methods and process conditions. Protein and lipid extraction processes was likewise screened and optimized, however, it was observed that the amount of lipid in the Salicornia ramosissima is too small for the lipid extraction to be feasible for this species. Therefore, the focus will be on the protein extraction from the green Salicornia ramosissima. The lignocellulosic fibres left after extraction were treated by organosolv pretreatment for the production of ylooligosaccharides and the residue fractions was screened and optimized for biomethane production.

The first trial batches of functional feed and dairy products and cosmetics have been produced and ongoing testing of the cosmetic cream on human subjects is showing promising results for pain and itch relieve. The first sets of shrimp and Seabass feeding trials with inclusion of Salicornia ramosissima have been carried out and analysed. For shrimps fed with Salicornia ramosissima an increase in feed conversion ratio (FCR) was observed and in Seabass the FCR was the same as in the controls feed with commercial diets however, increase in DNA integrity and immune modulation was observed, showing great potential for Salicornia ramosissima to be supplemented to shrimp and fish feed with the potential of increasing immunity and potentially use of less antibiotics in aquaculture. Stage 1 of the AQUACOMBINE bioprocess demonstration plant has been built at Aalborg University, so that larger amount of washed, shredded, and fractionated biomasses can be delivered to project partners. For the large extractor (tonne scale) designs are in progress. The aquaponics demonstration plant at Alpha Aqua is under construction and production will commence second half of 2021.
The AQUACOMBINE project represents a new business model where “closed loop” aquaculture and halophyte farming will be combined. Traditional aquaculture is primarily carried out in offshore basins, with little control of effluent and chemotherapeutics/antibiotics discharge to the surrounding environment, carrying an increasing awareness and concern. In a recirculating aquaculture system, the culture water is purified and reused continuously. A recirculating aquaculture system (RAS), such as the system that will be demonstrated in this project, is an almost completely closed circuit. The produced waste products solid waste, ammonium and CO2 are either removed or converted into non-toxic products using bioremediation and biofiltration. The Alpha-Aqua system, which will be demonstrated in this project, can be placed on-shore in almost any location and the combined halophyte cultivation can be in add-on hydroponics systems or on surrounding non-agricultural land.

The AQUACOMBINE project is directly targeting the goal of circular development by addressing and valorizing two important residues from one very established food industry (aquaculture) and one emerging food industry (halophyte cultivation). Halophyte plants such as Salicornia have a wide range of valuable molecules that can be utilized. This can range from simple “cheap” conversion - yielding medium value products - to more sophisticated conversion - yielding very high value products. The AQUACOMBINE project will create great business opportunities for rural and remote areas and create jobs in several sectors, such as development, engineering, fabrication, installation and operation of Aquaculture, halophyte cultivation, and bio-products processing plants (bio refineries).
Main objective of AQUACOMBINE: Demonstration of combined fish and halophyte production