On-line biofouling monitoring and qualification based on local thermal and periodic excitation with MEMS sensor

International audienceWater and wastewater processing (cooling tower, heat exchanger, treatment, etc.) generate desirable or undesirable biofouling (mineral, organic, biological) which may affect equipment or process performances. Fouling magnitude and nature stand as critical parameters to be evaluated in-situ and on-line to control and optimize the operation (production, cleaning). A fouling sensor based on a Micro-Electro-Mechanical Systems (MEMS) structure generating a local in-situ periodic thermal excitation (PTR) was studied in order to quantify and qualify fouling. At lab scale, model deposit (PVC) were used to simulate fouling conditions. Limits of detection (LOD) and quantification (LOQ) under steady and periodic thermal regimes were compared. Transposition to industrial conditions was investigated at pilot plant scale. A continuous bioprocess (PropellaTM reactor) was fed with diluted wastewater under controlled operating condition (temperature, mixing rate, flow rates, residence time) in order to mimic realistic industrial conditions and to generate a complex biofouling over six weeks. Thermal diffusivity, capacitive and resistive components are extracted from thermal spectrum response and a final fouling factor is introduced. Results demonstrate the ability to quantify and qualify a complex biofouling with in-situ and on-line information

On-line local thermal pulse analysis sensor to monitor fouling and cleaning: Application to dairy product pasteurisation with an ohmic cell jet heater

International audienceIn the process industry, fouling is considered as a complex (sometimes partially known and identified) phenomenon. In this paper, a fouling sensor (FS) based on local differential thermal analysis is scrutinized and we report the comparison of two operating modes, steady (STR) and periodic (PTR) thermal regimes. Moreover, the development of alternating technologies like direct joule effect (ohmic) heating to pasteurise and sterilise liquid food products in a continuous process is of great scientific and industrial interest. Heat treatment by direct Joule effect exhibits numerous advantages because rapid heating kinetics or homogeneous heat treatment is required. However, fouling of electrode surfaces in this kind of apparatus is much more problematic than in conventional heat exchangers. In the present study, a new continuous ohmic heating apparatus (Emmepiemme (R), Piacenza, Italy) in which an alternating electrical current is applied directly to a jet falling between two stainless steel electrodes is investigated during pasteurisation of a dairy product. Conventional fouling measurements (pressure drop, heat transfer or electrical parameters) cannot be used in such a heater. Fouling and cleaning phases are monitored with fouling sensor and fouling quantified

Bioperformance interpretation of a two-stage bioreactor with cell recycle considering residence time and internal age distributions of biomass

International audienc

Metrological performances of fouling sensors based on steady thermal excitation applied to bioprocess

International audienceFood and industrial bioprocesses are impacted by (biolfouling which generates failures from reduction of process efficiency (ex: reduction of heat transfer coefficient) up to health risk issue (e.g. biofilm formation). In present work, 3 fouling sensors based on a thermal excitation (steady thermal regime) were developed and described. These sensors were designed with different technologies (macro structure and Micro-Electro-Mechanical-Syste ms MEMS), geometries (intrusive cylindrical, flush plan) and packaging (presence or absence of cover panel) and compared. Laboratory setups were designed to characterize sensor responses under controlled operating conditions in batch and continuous process including clean condition and using layers of adhesive tape to simulate fouled conditions. Thermal responses from excitation under steady thermal regime at different heat flux were linearized then discussed as function of technology, geometry and packaging impacts. Packaging heat resistance, response times, efficient heat flux, and quantification of fouling were investigated. Finally, metrological limits were identified

Towards a Microbial Production of Fatty Acids as Precursors of Biokerosene from Glucose and Xylose Vers une production microbienne d’acides gras en vue de l’application biokérosène à partir de glucose et xylose

The aviation industry considers the development of sustainable biofuels as one of the biggest challenges of the next ten years. The aim is to lower the environmental impact of the steadily increasing use of fossil fuels on climate change, yielding greater energy independence and fuel security. Thus, the development of a new route for the production of lipids from renewable non-food resources is now being promoted with the recent ASTM certification of hydrotreated oils. Our study focuses on the potential of growth of the oleaginous yeast Rhodotorula glutinis using glucose and xylose which can come from renewable lignocellulosic substrates and of lipid accumulation using glucose as substrate. Experiments were carried out in fed-batch mode which allowed feed flux management. Carbon fluxes were controlled with modifying xylose/glucose ratios to quantify metabolism in optimal growth condition. Besides, the management of carbon and nitrogen fluxes allowed characterizing lipid accumulation. Thus, it has been shown that the yeast Rhodotorula glutinis can simultaneously consume glucose and xylose. When the ratio xylose/glucose increased, the growth rate and the carbon conversion yield into biomass decreased: it was of 0.36 h-1 and 0.64 Cmol x*.Cmol glu-1 for pure glucose, it was of 0.15 h-1 and 0.56 Cmol.Cmol-1 for 10% xylose and it was of 0.037 h-1 and 0.18 Cmol.Cmol-1 for pure xylose. The necessity to maintain residual growth and to manage carbon fluxes to optimize lipid accumulation performance was revealed. Lipid accumulation on glucose engendered a final biomass concentration of 150 gCDW.L-1, microbial production (72% of lipids) and maximal productivity over 1.48 glip.L-1.h-1. The culture temperature is an important parameter to modulate the lipid profile. The results were encouraging. Lipid accumulation using lignocellulosic feedstock was shown to be a highly promising route. <br> Le développement de filières de production de molécules énergétiques en substitution au kérosène constitue un défi majeur pour l’industrie aéronautique afin de minimiser l’impact environnemental de son activité et de répondre à ses besoins en énergie, dont la demande est croissante. Le développement d’une nouvelle voie de production de lipides à partir de ressources renouvelables non alimentaires ouvre des perspectives prometteuses avec la certification ASTM des huiles hydrotraitées. Les travaux expérimentaux consistent en l’étude, d’une part, des potentialités de croissance de la levure oléagineuse Rhodotorula glutinis à partir de glucose et/ou xylose, substrats osidiques issus des ressources lignocellulosiques, et d’autre part, des potentialités d’accumulation de lipides à partir de glucose. Des cultures en mode fed-batch ont permis le contrôle des flux d’alimentation : en carbone, en condition de croissance, selon un ratio xylose/glucose variable pour la quantification du métabolisme, et en azote, en condition de production de lipides. Il a été montré que la levure Rhodotorula glutinis est capable de consommer simultanément le glucose et le xylose. Le taux de croissance et le rendement de conversion du carbone en biomasse diminuent en fonction de la composition du mélange xylose/glucose : à savoir 0,36 h-1 et 0,43 Cmol. x*.Cmol glu-1 sur glucose pur, 0,15 h-1 et 0,56 Cmol.Cmol-1 sur 10 % de xylose, 0,037 h-1 et 0,18 Cmol.Cmol-1 sur xylose pur. Par ailleurs, lors d’expérimentation en condition. d’accumulation lipidique, il a été mis en évidence la nécessité de maintenir une croissance résiduelle par le contrôle des flux d’azote et de carbone. Lors de la phase de production de lipides sur glucose, il a été ainsi obtenu une concentration finale en biomasse de 150 gCDW.L-1 contenant 72 % de lipides en masse; la productivité volumétrique maximale atteint 1,5 glip.L-1.h-1, avec un rendement de conversion du glucose en lipides égal à 95 % du rendement théorique limite La température de culture se révèle un paramètre opératoire important pour la modulation du profil lipidique. Ces résultats sont originaux et ils ont permis l’obtention de très hautes performances, en culture intensive. Ils argumentent des potentialités de développement d’une stratégie de production de lipides par conversion de toutes les fractions osidiques des substrats lignocellulosiques pour des usages biokérosène après hydrotraitement

Contrôle d'un encrassement laitier en procédé continu : comparaison de trois méthodes

National audienc