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A bioreactor using membrane technologies was used to demonstrate the feasibility of in-situ bio-methanation coupled to industrial wastewater treatment for biogas upgrading. High biogas productivity (1.7 Nm

International audience; A bioreactor using membrane technologies was used to demonstrate the feasibility of in-situ bio-methanation coupled to industrial wastewater treatment for biogas upgrading. High biogas productivity (1.7 Nm 3 Biogas/m 3 Bioreactor/day) with high CH4 content (97.9%) was reached. In-situ bio-methanation did not affect the COD removal efficiency of anerobic digestion (>94%). Process resilience has been tested for both substrate overload and H2 intermittence injection. Recovery of high CH4 content after 7 days without H2 injection occurred within few hours. Influence of microbial community has been studied showing that both hydrogenotrophic and homoacetogenic-acetoclastic pathways were involved.

International audience; A pilot-scale anaerobic membrane bioreactor (AnMBR) was designed and optimized for the treatment of real distillery wastewater. A low hydraulic retention time of 3.5 days was reached after only 3 weeks. The AnMBR could treat up to 3.97 g COD /L/day with high biogas production at 1.36 NL biogas /L bioreactor /day. The performances of an AnMBR and an anaerobic packed-bed bioreactor for treating the same wastewater were compared. The AnMBR had a shorter start-up period (21 days), a higher COD removal efficiency (96.9 %), and higher stability and methane production (0.26 L CH4 /g CODinput), indicating the interest of investigating AnMBR industrialization. The membrane performance was also studied, demonstrating a long cleaning cycle interval of at least 44 days. The transmembrane pressure and Food-to-Microorganism ratio were defined to minimize membrane fouling without affecting the anaerobic digestion performance.

CO2 removal from binary mixture gaseous streams using hollow fibers membrane module under physical absorption (water) has been investigated. The impact of the gas composition on the mass transfer efficiency was experimentally investigated with a CO2/CH4 mixture of varying composition ( y CO 2 in = 10 − 90 % ), covering a wide range of process: natural gas sweetening (5–10% CO2), post-combustion carbon capture (10–15% CO2), for biogas upgrading to biomethane (35–50% CO2), … As expected, the absorbed CO2 flux is increasing with the CO2 partial pressure. Yet the absorbed CO2 flow is multiplied by a factor up to 15 between a 10% and a 90% inlet CO2 molar fraction, while applying a factor 9 to the inlet flow parameters. This underlines the existence of a non-trivial behavior. In the meantime, a 2D numerical model describing the absorption of CO2 in a binary gas mixture, based on the internal module geometry and on a local description of the hydrodynamics was proposed. Its development showed that in order to capture the key phenomena, a proper description of mass transfer in transition zone (Knudsen number around 0.34) is mandatory. Implementing this description allowed the model to accurately describe mass transfer over a wide range of gas composition and flow rate, without relying on any fitted parameter.

International audience; Membrane wetting is a limitation to mass transfer in industrial Hollow-Fiber Membrane Modules (HFMM). The influence of transmembrane pressure on wetting is investigated through both experimental and numerical works. On the one hand, experiments for CO2 absorption in softened water are carried out at pilot scale with Liqui-Cel Extra-Flow modules operating in a cross-flow mode. After several hours of operation (50-300 min), the membrane partially wetted mode is established at steady state and decreases the absorbed CO2 flowrates up to 10.5% compared to membrane dry mode. Interestingly, CO2 absorption is found to be independent on different transmembrane pressure (0.5 and 2.5 bar), both in the dry and partially wetted mode. On the other hand, a 2D predictive tool is developed to help in the design of HFMM gas absorption systems. The model depicts the complex hydrodynamics in commercial cross-flow modules. The liquid in the shellside is flowing through the fiber bundle considered as a porous medium. The liquid mass-transfer coefficient is non-uniform over the membrane module and is estimated at a local scale. The parameters from the empirical Chilton-Colburn correlation are optimized with experimental results in the dry mode through a Particle Swarm Optimization (PSO) algorithm. The simulation results are in good agreement with the experiments (-131+17%). In the partially wetted mode at steady state, wetting is then described by considering a log-normal pore size distribution and the Laplace-Young equation. The transmembrane pressure decreases the simulated absorbed CO2 flowrate. By comparing to experimental data, the numerical relative error is increasing with transmembrane pressure. Therefore, a suggestion is made to adapt the description of wetting in HFMM gas -liquid models.

International audience; The agro-industrial sector generates large amounts of coproducts such as lignocellulosic biomass which could be valorized into many chemicals and bio-based intermediates (sugars, paper pulp, surfactants, polymers or bioethanol). However, in the case of biomass hydrolysis by diluted sulfuric acid, current downstream processes involve a partial or complete neutralization which are not satisfactory for economic and environmental reasons. This work presents a purification process of pentoses from hemicellulosic hydrolysates without neutralization for sulfuric acid recovery. Compared to conventional processes, less energy, water and chemicals are required. Very promising results were obtained at pilot scale with 100 L of wheat bran hydrolysates. The process is based on the combination of ultrafiltration, Conventional electrodialysis and ion-exchange. Ultrafiltration with a 10 kDa organic membrane totally removed harmful macromolecules which precipitate during electrodialysis operation because of pH rise. Till a volumetric concentration factor 3.6, the average flux kept good for industrial application (27 L h(-1)m(-2)). However suspended materials have to be filtered before ultrafiltration. Besides, a 2.5 diafiltration is required to recover most of sugars (99%): Then conventional electrodialysis was performed to recover most of sulfuric acid (80%). The average faradic yield was quite good (80%) and the specific energy consumption of the electrodialysis stack was quite interesting (1.1 kW h per kg of H2SO4 recovered and 8.4 kW h per m(3) of hydrolysate). Finally, the complete demineralization (conductivity < 10 mu S cm(-1)) and discoloration (420 nm absorbance < 0.01) of the sugars solution was performed by ion-exchange and an activated carbon polishing treatment. The sugars purity was close to 100% meanwhile the overall sugars recovery rate reach about 90%. Finally we checked that the reused sulfuric acid solution was as efficient as a fresh one in a second hydrolysis operation of wheat bran. Recovery rates could be increased by a scale-up operation or a continuous mode of the process.

International audience; Bio-based organic acids are promising renewable carbon sources for the chemical industry. However energy-consuming purification processes are used, like distillation or crystallization, to reach high purities required in some applications. That is why preparative chromatography was studied as an alternative separation technique. In a previous work dealing with the purification of lactic, succinic and citric acids, the Langmuir model was insufficient to explain the elution profiles obtained with a strong anionic resin.Consequently the Langmuir model was coupled with a usual ion-exchange model to take into account the retention of their conjugate bases (

International audience; The valorization of lignocellulosic biomass as a renewable carbon source is growing in chemical industries, particularly in the agro-industrial sector. Many chemicals compounds and bio-based intermediates can be produced but their production needs to be more cost-competitive. The valorization of pentoses in hemicellulosic hydrolysates, obtained by using dilute sulfuric acid, is of growing interest. However, current downstream processes which involve a partial or complete neutralization of the acid are not satisfactory for economic and environmental reasons.This work presents a method of purification of pentoses with sulfuric acid recovery which reduces water and chemicals consumptions. The results obtained at the laboratory scale with wheat bran hydrolysates are very promising. The process is based on the combination of ultrafiltration, conventional electrodialysis and ion-exchange. A special organic UF membrane (Alpha Laval - UFX10pHt), resistant to acidic conditions, removed totally macromolecules which can damage the electrodialysis unit by precipitation, with good mean permeate flow rate (24 L h−1 m−2 till VCF = 4.4). Then, conventional electrodialysis was performed to recover most of sulfuric acid (>80%) without losing sugars (

Regeneration of resins used for decolorization of sugar solutions is done with concentrated salt solutions. Nanofiltration membranes have been proven effective, in terms of industrial efficiency in decreasing salt consumption. More than 90% of the salt that is necessary for regeneration can be recycled through a combination of direct recycling of intermediate eluates, the separation of colored compounds by use of very selective nanofiltration membranes and a multiple-effect evaporation of salty permeates. The desalted color compound solution is sent to the molasses, limiting considerably the effluent to be treated. Starting from a liquor of 800 IU, the water requirement is limited to less than 100 L/t of sugar and the amount of wastewater can be reduced to less than 40 L/t of sugar.

Hydrolysis of sucrose was performed in aqueous medium in the presence of various H-form dealuminated zeolites (H-BEA, H-MFI, H-MOR, H-Y-FAU). For all catalysts, hydrolysis takes place with a high selectivity whatever the conversion is. The important feature to be noted is the capacity for those catalysts to act as specific adsorbents of colored by-products formed during the course of the reaction, 5-hydroxymethylfurfural (HMF) in particular. The amount of this by-product can be reduced to less than 100 ppm, thus offering an alternative route for the production of colorless invert sugars. In this way, H-Y FAU (Si/Al=15) was found to have the better balance between activity, selectivity and by-product amount.