An innovative approach is proposed for the shellfish farming sector in order to make farming structures safer and more reliable with regard to the qualities of seawater not adapted to the management of sensitive organisms such as marine mollusc larvae or microalgae fodder produced within these structures.

To achieve these objectives, the project relies on three research teams from Aix-Marseille Université (AMU), the Ecole Nationale Supérieure de Chimie de Rennes (ENSCR) and the Institut Mines Télécom Atlantique (IMTA – GEPEA laboratory), on the French Institute for the Exploitation of the Sea (Ifremer) and on two commercial hatcheries, Vendée Naissain and Novostrea. The presence of all these partners from the research and economic world makes it possible to build a project with 5 coherent and complementary Work Packages (WP) to provide concrete answers to the targeted field of application. These WPs consist of scientific understanding (WP2-WP3), a validation in control conditions (WP4) before a technology transfer (WP5).

Task carried out by Aix-Marseille Université

Task carried out by the Ecole Nationale Supérieure de Chimie de Rennes

The WP2 will be structured in 3 parts:

1. Implementation of an analytical strategy and multi-residue analysis method to assess contamination of water resources used in aquaculture by organic micropollutants. The first step is to collect supply water from hatcheries in order to make an accurate assessment of the characteristics of the water and to determine the presence and concentration of organic micropollutants. An analytical strategy will be defined and applied to take into account seasonal effects and temporal variations (tides, meteorology, etc.). A first measurement campaign, based on a non-market/semi-targeted screening approach using high-resolution mass spectrometry coupled with chromatographic separation (LC and GC), will define a list of relevant molecules. It will also be necessary to carry out a phase of testing of several adsorbents under laboratory conditions in order to determine the most appropriate materials for the implementation of this process in seawater. The selection of adsorbents of different types (activated carbons, zeolites, resins) will be made in agreement between the project partners. Kinetics and adsorption capacities will be determined to select the best adsorbent for the intended application. Thus the laboratory reactor assessment of the adsorption capacities of several chemical contaminants including glyphosate and compounds generated by an upstream UV treatment on the adsorbents retained will be carried out.
2. Pilot unit laboratory studies on the identification of photolysis by-products and the understanding of the adsorption mechanisms of organic micropollutants in a seawater matrix. The seawater adsorption of the micropollutants on the selected adsorbent(s) will be evaluated through the implementation of laboratory-scale columns under controlled conditions.
3. Follow-up of a pilot scale unit installed within a shellfish hatchery. The treatment line includes a continuous UV oxidation/disinfection system followed by an activated carbon adsorption process and will confirm the results obtained in (2).

Task carried out by Aix-Marseille Université

This WP will involve developing the hybrid process that combines two processes, the fixation of dissolved pollution on an insoluble adsorbent (activated carbon) and ultrafiltration. Two configurations will be tested: a CRISTAL configuration where the ultrafiltration loop serves as an adsorption reactor and the membrane allows the retention of suspended solids present in the raw water, adsorbent (PAC-powdered activated carbon) having fixed dissolved pollutants, and undesirable germs: cysts, bacteria, viruses. This process makes it possible, for example, to produce drinking water from fresh water with a minimum of residual disinfectant. The main facilities have been in operation for more than 15 years, notably in Lausanne, Switzerland. However, in the context of more complex water such as seawater, the adsorption process is subject to competitive phenomena and if the UF backwash waters can be sent to the beginning of the treatment path, within the framework of this project, this could result in a release of PAC into the treatment path which is not desirable. A second configuration will also be studied with an adsorption reactor (GAC-granular activated carbon) downstream of the membrane process to avoid this dissemination and thus express its adsorption capacity. The UF process will protect the GAC column from suspended solids, bacterial development, etc. This will also limit, should this occur, the release of micropollutants as a result of peak pollution or peak concentrations of adsorbable organic matter. This type of process, in the context of a significant pollutant load, has already made it possible to consider on a semi-industrial scale (AMU) the disinfection of pool water with the retention by membrane of bacteria, viruses and other organic compounds capable of forming chloramines, and activated carbon to treat very small dissolved compounds ( 20nm). While the overall performance of the hybrid process will be studied, the process coupling raises several questions that the project will have to answer: backwash water fate, regeneration of activated carbon, time management of the two processes etc.

Task carried out by Ifremer

On the Marine Molluscs Experimental Platform of Bouin (Ifremer), an experimental implementation is possible for the water supply in the ponds of larvae/spat growth. An analytical follow-up is planned to verify the efficiency of the ultrafiltration/ activated carbon adsorption coupling developed but also to compare this new treatment with existing treatments (UV alone and UV + activated carbon). This WP4 is essential for technology transfer and in a unique way in France, the Ifremer platform of Bouin not only allows to work in controlled conditions of seawater used (from raw seawater to seawater treated by sand filter + UV + prefilter) but also to be able to work on spat in parallel allowing to follow their growth according to the process tested. In collaboration with La Tremblade’s Marine Molluscs platform, the technical solution to be adopted will be applied for the treatment of seawater before the realization of shellfish larval farms on species of interest in France whose two partner hatcheries are representative.

Task carried out by Ifremer and Aix-Marseille Université

Vendée Naissain and Novostrea, two shellfish hatcheries that produce hollow oyster spat for the first and flat oyster and clam spat for the second, destined for the French and international market, will be the final objective of this project. The complementarity of the partners will take its full meaning during this phase where two pilot plants adapted to the production conditions can be set up with the objectives of validating the technico-economic feasibility of integrating the UF + CA coupling and refining the CAPEX (capital expenditure) and OPEX (operational expenditure) calculated under controlled conditions (WP4), under real conditions (WP5).