Membrane reactors increased process efficiency

Rautenbach and MeUis [75] describe a process in which a UF-membrane fermentor and a subsequent NF-treatment of the UF-permeate are integrated. The retentate of the NF-step is recycled to the feed of the UF-membrane reactor (Fig. 13.8). This process has been commercialised by Wehrle-Werk AG as the Biomembrat -plus system [76] and is well suited for the treatment of effluents with recalcitrant components. The process also allows for an additional treatment process, like adsorption or chemical oxidation of the NF-retentate, before returning the NF-retentate to the feed of the UF-membrane fermentor. Usually, the efficiency of these treatment processes is increased as the NF-retentate contains higher concentrations of these components. Pilot tests with landfiU leachates [75] and wastewater from cotton textile and tannery industry have been reported [77]. An overview of chemical oxygen demand (COD) reduction and COD concentrations in the permeate are shown in... 

Coupling photocatalysis with a physical technologies, such as biological treatment [67, 68], membrane reactor [39] or physical adsorption, the combination does not affect the mechanisms but increases the efficiency of the whole process. 

Hydrogen from the membrane reactor is converted in a gas turbine with a high efficiency. The process efficiency will increase when the hydrogen production (CO conversion) and recovery (on the permeate side) from the membrane reactor is raised. CO2 abatement increases with increasing recovery of carbon components on the retentate side of the membrane. The performance of the reactor can be measured in terms of these three parameters. The boundary conditions for the membrane reactor in the total system depends upon final... 

It has been shovm that membranes can enhance the conversion of a water-gas shift membrane reactor and concurrently separate hydrogen from carbon dioxide. The efficiency of CO2 control using the membrane reactor with a H2/CO2 selectivity of 15 is significantly higher compared to a conventioncd technique (i.e. wet washing with a sorbent). It is not necessary to exceed a selectivity of approximately 40 for H2/CO2 for the process under consideration, because further increase in reactor performance seems marginal. Enlargement of the permeation is an important aspect on the other hand, so that the total surface area necessary for the full-scale application can be reduced. 

Biocatalytic membrane reactors combine selective mass transport with chemical reactions and the selective removal of products from the reaction site increases the conversion of product-inhibited or thermodynamically unfavorable reactions. Membrane reactors using biological catalysts can be used in production, processing and treatment operations. Recent advances towards environmentally friendly technologies make these membrane reactors pai ticulaiiy attractive because they do not require additives, are able to function at moderate temperatures and pressrue, and reduce the formation of by-products. The catalytic action of enzymes is extremely efficient and selective compared with chemical catalysts. Uiese enzymes demonstrate higher reaction rates, milder reaction conditions and greater stereospecificity. 

Integration of reaction and separation in a single unit is a powerful tool to increase efficiency and economic advantages of many chemical processes. Reactive distillation, extraction, and adsorption are well-known examples of this technological resource. Recently, a very promising solution is offered by membrane reactors... 

Online monitoring and control of the biological denitrification process in a cell recyle membrane reactor has been developed and implemented at laboratory scale. The system has been tested with a real groundwater contaminated with nitrate. The results presented in this study show that the C7N ratio is the key parameter to guarantee an efficient denitrification process. A simple feedforward control strategy that adjusts the feed rate of the carbon source to maintain an inlet C/N ratio value of 1.39 is effective at reducing both nitrate and nitrite concentrations in the treated water below the maximum admissible values. Moreover, this control strategy based on the C/N ratio is easy to implement in a water treatment plant and does not increase the complexity of its operation at industrial scale. 

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