Silica monoliths with uniform macro-/mesoporous structures (20 µm and 20 nm macro-and mesopores diameters, respectively), high porosity (83%) and high surface area (370 m 2 g -1 ) were prepared. The monoliths were grafted with amino groups (0.9 mmol NH 2 g -1 ) and used to immobilize laccase from Trametes versicolor by covalent grafting with glutaraldehyde (GLU)(1.0 mmol GLU g -1 ) leading to an ABTS activity of 20 U g -1 . Immobilization yield was 80%, based on the difference of initial and final activity of enzymatic solution used for immobilization. Enzymatic monoliths were used for the degradation of tetracycline (TC) in aqueous solution (20 mg L -1 ) in continuous flow with recycling configuration. TC degradation efficiency was found to be 40-50 % after 5 h of reaction at pH 7. Enzymatic monoliths were used during 75 hours of sequential operation without losing activity. A Steady-state computational fluid dynamics (CFD) model based on Michaelis Menten reaction kinetics, allowed computing TC degradation efficiency.

Pharmaceutical products (PPs) are considered as emerging micropollutans in wastewaters, river and seawaters, and sediments. The biodegradation of PPs, such as ciprofloxacin, amoxicillin, sulfamethoxazole, and tetracycline by enzymes in aqueous solution was investigated. Laccase from Trametes versicolor was immobilized on silica monoliths with hierarchical meso-/macropores. Different methods of enzyme immobilization were experienced. The most efficient process was the enzyme covalent bonding through glutaraldehyde coupling on amino-grafted silica monoliths. Silica monoliths with different macropore and mesopore diameters were studied. The best support was the monolith featuring the largest macropore diameter (20 µm) leading to the highest permeability and the lowest pressure drop and the largest mesopore diameter (20 nm) ensuring high enzyme accessibility. The optimized enzymatic reactor (150 mg) was used for the degradation of a PP mixture (20 ppm each in 30 ml) in a continuous recycling configuration at a flow rate of 1 ml/min. The PP elimination efficiency after 24 h was as high as 100% for amoxicillin, 60% for sulfamethoxazole, 55% for tetracycline, and 30% for ciprofloxacin.

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Background In this research work, a coupled heat and mass transfer model was developed for salt recovery from concentrated brine water through an osmotic membrane distillation (OMD) process in a hollow fiber membrane contactor (HFMC).The model was built based on the resistance-in-series concept for water transport across the hydrophobic membrane. The model was adopted to incorporate the effects of polarization layers such as temperature and concentration polarization, as well as viscosity changes during concentration. Results The modeling equations were numerically simulated in MATLAB® and were successfully validated with experimental data from literature with a deviation within the range of 1–5%. The model was then applied to study the effects of key process parameters like feed concentrations, osmotic solution concentration, feed, and osmotic solution flow rates and feed temperature on the overall heat and mass transfer coefficient as well as on water transport flux to improve the process efficiency. The mass balance modeling was applied to calculate the membrane area based on the simulated mass transfer coefficient. Finally, a scale-up for the MD process for salt recovery on an industrial scale was proposed. Conclusions This study highlights the effect of key parameters for salt recovery from wastewater using the membrane distillation process. Further, the applicability of the OMD process for salt recovery on large scale was investigated. Sensitivity analysis was performed to identify the key parameters. From the results of this study, it is concluded that the OMD process can be promising in salt recovery from wastewater.

In this work, the laccase from Trametes versicolor was immobilized in highly porous silica monoliths (0.6 cm diameter, 0.5 cm length). These monoliths feature a unique homogeneous network of interconnected macropores (20 μm) with mesopores (20 nm) in the skeleton and a high specific surface area (330 m 2 /g). The enzymatic monoliths were applied to degrade tetracycline (TC) in model aqueous solutions (20 ppm). For this purpose, a tubular Flow-Through-Reactor (FTR) configuration with recycling was built. The TC degradation was improved with oxygen saturation, presence of degradation products and recirculation rate.The TC depletion reachs 50% in the FTR and 90% in a stirred tank reactor (CSTR) using crushed monoliths.These results indicate the importance of maintaining a high co-substrate concentration near active sites. A model coupling mass transfers with a Michaelis-Menten kinetics was applied to simulate the TC degradation in real wastewaters at actual TC concentration (2.8 10 -4 ppm). Simulation results show that industrial scale FTR reactor should be suitable to degrade 90% of TC in 5 h at a flow rate of 1 mL/min in a single passage flow configuration. Nevertheless, the process could certainly be further optimized in terms of laccase activity, oxygen supply near active sites and contact time.

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