Air Backwash Efficiency on Organic Fouling of UF Membranes Applied to Shellfish Hatchery Effluents

Among all the techniques studied to overcome fouling generated in dead-end filtration, the injection of air during backwashes proved to be the most effective. Indeed, shear stress engendered by the two-phase flow enhanced particle removal on membrane surface. This work aims to study the injection of air to drain the membranes before backwash. Firstly, the efficiency of this backwash procedure was evaluated during the ultrafiltration of seawater on a semi industrial pilot plant using different operating conditions. Then, the treatment of seawater, doped with oyster gametes to simulate the filtration of shellfish hatchery effluents, was performed to confirm the hydraulic performance of the air backwash. Indeed, the release of gametes, expulsed by exotic bivalves in the natural environment, could be a risk for the biodiversity preservation. The impact of air backwash on the integrity of oocytes and spermatozoa was identified using flow cytometry and microscopic analyses. When oyster gametes were added, their retention by ultrafiltration was validated. The impact of air backwash on these species viability was a significant information point for the implementation of this process on shellfish production farms

Culture of Microalgae with Ultrafiltered Seawater : A Feasibility Study

International audienceThe culture of microalgae is important for the production and maintenance of bivalves. One of the major challenges is to maintain the reliability of microalgae forages over the long term. The aim of this work is to use Ultrafiltered (UF) seawater to cultivate them. Thus, cultures in a volume of 300 L of 2 species of microalgae Tetraselmis and T-isochrysis, were monitored in UF water (membrane pore size: 20 nm) and in sea water usually used on the Ifremer mollusk experimental platform of Bouin (France) (Prefiltration, 3 filtrations and 2 UV). The major result is the securing of microlagae cultures with the absence of parasites in all cultures supplied with ultrafiltered water, unlike analyses of the various control cultures. In the case of T-isochrysis, 3 cultures out of 4 resulted in higher microalgae concentrations, up to 30%, in ultrafiltered water thus bringing a benefit on the algal density. These conclusions and the ease of recovering water (linked to the reduction in treatment stages) allowed a transfer of technology. In fact the 300 L cultures hitherto carried out on the experimental platform are now produced in ultrafiltered water since early 2019

Ultrafiltration for environmental safety in shellfish production: A case of bloom emergence

The process of ultrafiltration (UF) of natural seawater often encounters the problems of variation in water quality and coastal blooms. To validate the feasibility of UF in shellfish farms, this study compared the hydraulic performance and pollutant removal efficiency of the UF process with those of the commonly used treatments that combine several filtration steps with UV disinfection. The comparison was conducted in the cases of natural seawater and a coastal bloom. Given that the UF process encountered this specific pollution, this study evaluated the filtration performance of the UF process and the retention of total suspended solids (TSS), bacteria, phytoplankton, and zooplankton. A real coastal bloom was considered in the case study of an experimental shellfish hatchery/nursery in France. The results show that both treatments were able to eliminate approximately 50% of TSS. However, in contrast with UV treatment combined with filtration, the UF process retained total amounts of phytoplankton, zooplankton, and bacteria in the bloom. Although the hydraulic performance of the UF process was impacted by the coastal bloom, the fouling was eliminated through chemical cleaning conducted at a frequency less than once per 12 h. Despite the severe pollution, this study confirmed the pollution resistance and treatment performance of the UF process, indicating that UF has the potential to enhance the biosecurity level

Culture of Microalgae with Ultrafiltered Seawater : A Feasibility Study

International audienceThe culture of microalgae is important for the production and maintenance of bivalves. One of the major challenges is to maintain the reliability of microalgae forages over the long term. The aim of this work is to use Ultrafiltered (UF) seawater to cultivate them. Thus, cultures in a volume of 300 L of 2 species of microalgae Tetraselmis and T-isochrysis, were monitored in UF water (membrane pore size: 20 nm) and in sea water usually used on the Ifremer mollusk experimental platform of Bouin (France) (Prefiltration, 3 filtrations and 2 UV). The major result is the securing of microlagae cultures with the absence of parasites in all cultures supplied with ultrafiltered water, unlike analyses of the various control cultures. In the case of T-isochrysis, 3 cultures out of 4 resulted in higher microalgae concentrations, up to 30%, in ultrafiltered water thus bringing a benefit on the algal density. These conclusions and the ease of recovering water (linked to the reduction in treatment stages) allowed a transfer of technology. In fact the 300 L cultures hitherto carried out on the experimental platform are now produced in ultrafiltered water since early 2019

Culture of Microalgae with Ultrafiltered Seawater : A Feasibility Study

International audienceThe culture of microalgae is important for the production and maintenance of bivalves. One of the major challenges is to maintain the reliability of microalgae forages over the long term. The aim of this work is to use Ultrafiltered (UF) seawater to cultivate them. Thus, cultures in a volume of 300 L of 2 species of microalgae Tetraselmis and T-isochrysis, were monitored in UF water (membrane pore size: 20 nm) and in sea water usually used on the Ifremer mollusk experimental platform of Bouin (France) (Prefiltration, 3 filtrations and 2 UV). The major result is the securing of microlagae cultures with the absence of parasites in all cultures supplied with ultrafiltered water, unlike analyses of the various control cultures. In the case of T-isochrysis, 3 cultures out of 4 resulted in higher microalgae concentrations, up to 30%, in ultrafiltered water thus bringing a benefit on the algal density. These conclusions and the ease of recovering water (linked to the reduction in treatment stages) allowed a transfer of technology. In fact the 300 L cultures hitherto carried out on the experimental platform are now produced in ultrafiltered water since early 2019

Ultrafiltration for environment safety in shellfish production: removal of oyster gametes in hatchery effluents

Triploid oysters are favoured by the aquaculture industry because of their sterility, which results in two advantages: a faster growth than natural oysters and a constant quality throughout all the year, which is attractive for consumers. In France, these oysters are mainly produced by mating natural and tetraploid oysters whose production poses a risk for marine environmental biodiversity if biological material is released into the environment. Therefore, effluents from farms which could produce those kinds of oysters must be treated. The objective of this work was to treat shellfish hatchery effluents by ultrafiltration. The retention of gametes by the membrane, was validated for different scenario, 5 log removals were obtained, and their viability was evaluated after treatment highlighting a destruction of these species after air-backwash. The sustainability of the process facing this organic pollution on the duration of each test but also on the period of the study was demonstrated. A protection of the marine environment biodiversity is obtained with ultrafiltration processes

Traitement d'effluents conchylicoles par ultrafiltration

National audienceEn aquaculture, la gestion de l’eau entrante et des effluents requiert l’utilisation de procédés de traitement et de désinfection en milieu salin. C’est particulièrement le cas dans un contexte actuel de crise sanitaire affectant les animaux. La conchyliculture notamment, doit faire face à deux enjeux : la dégradation des eaux côtières, par la présence de pathogènes responsables de mortalités sur les huîtres juvéniles et adultes, mais aussi la préservation de l’environnement face à la production d’huîtres exotiques. Dans cette étude, l’objectif est de traiter les effluents d’écloseries conchylicoles dans le cas de la production d’huîtres dites de quatre saisons. Contrairement aux huîtres naturelles diploïdes, ces huîtres triploïdes sont stériles. Cette particularité leur confère deux avantages : leur croissance est plus rapide que les huitres naturelles et leur qualité gustative reste constante tout au long de l’année puisqu’elles n’entrent pas en gamétogénèse ..

L'ultrafiltration, une solution pour les élevages conchylicoles

International audienceLes huîtres triploïdes, stériles contrairement aux huîtres naturelles diploïdes, présentent deux avantages : leur croissance est plus rapide que les huîtres naturelles et leur qualité gustative reste constante tout au long de l’année. Elles sont principalement produites en France en croisant des huîtres diploïdes et des huîtres tétraploïdes [1]. Or, la production de ces huîtres tétraploïdes présente un risque pour la biodiversité du milieu marin si du matériel biologique était libéré. L'objectif de la thèse est double, la protection des élevage

L'ultrafiltration, une solution pour les élevages conchylicoles

International audienceLes huîtres triploïdes, stériles contrairement aux huîtres naturelles diploïdes, présentent deux avantages : leur croissance est plus rapide que les huîtres naturelles et leur qualité gustative reste constante tout au long de l’année. Elles sont principalement produites en France en croisant des huîtres diploïdes et des huîtres tétraploïdes [1]. Or, la production de ces huîtres tétraploïdes présente un risque pour la biodiversité du milieu marin si du matériel biologique était libéré. L'objectif de la thèse est double, la protection des élevage

Traitement d'effluents conchylicoles par ultrafiltration

National audienceEn aquaculture, la gestion de l’eau entrante et des effluents requiert l’utilisation de procédés de traitement et de désinfection en milieu salin. C’est particulièrement le cas dans un contexte actuel de crise sanitaire affectant les animaux. La conchyliculture notamment, doit faire face à deux enjeux : la dégradation des eaux côtières, par la présence de pathogènes responsables de mortalités sur les huîtres juvéniles et adultes, mais aussi la préservation de l’environnement face à la production d’huîtres exotiques. Dans cette étude, l’objectif est de traiter les effluents d’écloseries conchylicoles dans le cas de la production d’huîtres dites de quatre saisons. Contrairement aux huîtres naturelles diploïdes, ces huîtres triploïdes sont stériles. Cette particularité leur confère deux avantages : leur croissance est plus rapide que les huitres naturelles et leur qualité gustative reste constante tout au long de l’année puisqu’elles n’entrent pas en gamétogénèse ..