Marc Aurousseau

Carrier-free co-immobilization of xylanase, cellulase and β-1,3-glucanase as combined cross-linked enzyme aggregates (combi-CLEAs) for one-pot saccharification of sugarcane bagasse

Combined cross-linked enzyme aggregates (combi-CLEAs) are an innovative prospect and a lucrative technology. The present study addresses the preparation, characterization and application of combi-CLEAs with xylanase, cellulase and β-1,3-glucanase to achieve one-pot bioconversion of lignocellulosic biomass to fermentable sugars. A three-phase partitioning (TPP) method was used to aggregate the enzymes. Glutaraldehyde (100 mM) was employed as a cross-linker with the cross-linking time of 7.5 h. Scanning electron microscopy of the tri-enzyme biocatalyst has a coarse-grained appearance. Combi-CLEAs were more thermally stable, retaining about 70% of their initial activity at 70 °C compared to 30% for the free enzyme. The storage stability of combi-CLEAs was more than 97% of their activity after incubation for 11 weeks at 4 °C, whereas the free enzymes retained about 65% of initial activity. The residual activity of combi-CLEAs remained constant at 90% until the sixth cycle. Contrary to free enzymes that remain in the hydrolysate, which prevents their recovery, reuse of combi-CLEAs was possible. Free enzymes hydrolyze the ammonia cooked sugarcane bagasse at about 73%, whereas the combi-CLEAs resulted in maximum hydrolysis of about 83.5% in 48 h.

TOWARDS AN INTEGRATED CO-OPERATIVE SUPERVISION SYSTEM FOR ACTIVATED SLUDGE PROCESSES OPTIMISATION

Abstract This paper deals with the design of an integrated co-operative supervision system to optimise activated sludge wastewater treatment. For this purpose a biological wastewater treatment pilot plant, suitable for industrial up scaling and composed of a biological reactor, a settler, sludge recirculation and aeration systems, has been carried out. The reactor configuration is adjustable to treat both urban and industrial wastewater. The pilot plant scale allows to reproduce industrial hydrodynamics and is illustrated by RTD (Residence Time Distribution) measurements. The supervisory system includes instrumentation and industrial supervisor. The integrated co-operative supervision approach emphases the importance of process behavior anticipation. Information for the human operator will be extracted from a suitable model and a state estimator, which results are presented.

Bioconversion of Lignocellulosic Biomass to Fermentable Sugars by Immobilized Magnetic Cellulolytic Enzyme Cocktails

Enzyme cocktails of reusable, highly stable cellulolytic enzymes play an inevitable role in bioconversion of biomass to biofuels economically. Cellulase, xylanase and β-1,3-glucanase bound silica-amine functionalized iron oxide magnetic nanoparticles (ISN-CLEAs) were prepared and used as the biocatalyst for the depolymerization of cellulosic biomass into monomeric sugar in the present study. The Fe3O4-NPs and Fe3O4@SiO2-NH2-NPs and ISN-CLEAs had an average hydrodynamic size of 82.2, 86.4, and 976.9 nm, respectively, which was confirmed by dynamic light scattering (DLS). About 97% of protein binding was achieved with 135 mM glutaraldehyde at 10 h of cross-linking time and successful binding was confirmed by Fourier transform infrared spectroscopy (FTIR). The ISN-CLEAs exhibited the highest thermal stability of 95% at 50 °C for 2 h and retained extended storage stability of 97% compared to 60% of its free counterpart. Besides, cross-linking allowed ISN-CLEAs reuse for at least eight consecutive cycles retaining over 70% of its initial activity. ISN-CLEAs exhibited approximately 15% increase in carbohydrate digestibility on sugar cane bagasse and eucalyptus pulp than the free enzyme.

Dynamic Modeling of an Activated Sludge Process: Case Study on Paper Mill Effluents

AbstractThe aim of this paper is to propose a step by step method to establish and validate a relevant, dynamical model of the activated sludge process for the paper mill industry. The model is established by considering the specificities of the effluent to be treated. It uses the biochemical oxygen demand (BOD) measurement, which allows a direct correlation between the state variables of the model and the measurements. This model is validated on a pilot plant of semi-industrial size fed with industrial paper mill effluents. The parameter estimation is based on an analysis of the sensitivities. The results are compared with a model based on chemical oxygen demand (COD) partitioning which is issued from the simplification of the activated sludge model number 1 (ASM1) model. Finally, the model dealing with BOD measurements not only shows the best performances, but is also the easiest to implement, overcoming one main obstacle to efficient monitoring and control in paper mill wastewater treatment plants.

Innovative Ozone/Oxygen Reactive Flotation for Paper Deinking

To improve paper recycling, the potential of an innovative deinking process using a reactive ozone/oxygen gas mixture instead of air was studied on two recovered paper furnishes (offset print and newsprint/magazine mixture). Using suitable O3 concentrations, ink removal, following first-order kinetics, increased and losses dropped leading to better selectivity than using air alone. The ozone benefits in term of selectivity depended on temperature and paper furnishes and reached 100% for newsprint/magazine furnish at ambient temperature. Finally deinking effluent COD was significantly reduced and the ozone-based flotation allowed the reduction of the alkaline chemistry used before flotation.

PAPERMILL WASTEWATER TREATMENT: MODEL DESIGN AND VALIDATION ON PILOT PLANT

Pulp and paper industry discharges a very important amount of effluent, which includes a major part of carbonaceous pollution. This wastewater is usually treated by biological treatment. This paper deals with the design of a model dedicated to paper mill wastewater treatment. Validation is carried out on a real industrial effluent thanks to a semi-industrial pilot plant.