Membrane bioreactors case study

Membrane bioreactors have been reviewed previously in every detail [3,4,7,8,18], There are two main types of membrane bioreactors (i) the system consists of a traditional stirred-tank reactor combined with a membrane separation unit (Figure 14.1) (ii) the membrane contains the immobilized biocatalysts such as enzymes, micro-organisms and antibodies and thus, acts as a support and a separation unit (Figure 14.2). The biocatalyst can be immobilized in or on the membrane by entrapment, gelification, physical adsorption, ionic binding, covalent binding or crosslinking [3, 7, 18]. Our attention will be primarily focused on the second case where the membrane acts as a support for biocatalyst and as a separation unit, in this study. The momentum and mass-transport process, in principle, are the same in both cases, namely when there is... 

Membrane technology may become essential if zero-discharge mills become a requirement or legislation on water use becomes very restrictive. The type of membrane fractionation required varies according to the use that is to be made of the treated water. This issue is addressed in Chapter 35, which describes the apphcation of membrane processes in the pulp and paper industry for treatment of the effluent generated. Chapter 36 focuses on the apphcation of membrane bioreactors in wastewater treatment. Chapter 37 describes the apphcations of hollow fiber contactors in membrane-assisted solvent extraction for the recovery of metallic pollutants. The apphcations of membrane contactors in the treatment of gaseous waste streams are presented in Chapter 38. Chapter 39 deals with an important development in the strip dispersion technique for actinide recovery/metal separation. Chapter 40 focuses on electrically enhanced membrane separation and catalysis. Chapter 41 contains important case studies on the treatment of effluent in the leather industry. The case studies cover the work carried out at pilot plant level with membrane bioreactors and reverse osmosis. Development in nanofiltration and a case study on the recovery of impurity-free sodium thiocyanate in the acrylic industry are described in Chapter 42. 

Various chapters on membrane reactors (MR) consider different aspects of the integration of membranes with other conventional systems pervapo-ration, zeolite, bioreactors, fuel cells, wastewater treatment, systems for electrical energy, and so on. However, among the various possible examples not cited in these chapters, in the following, due to the lack of space, only seven, but very interesting, case studies are taken in consideration. 

In particular, techniqnes based on conpUng membrane processes and appropriate complexing agents, snpported Uqnid membranes (SLMs), pervaporation (PV) and membrane bioreactors (MBRs) are reviewed and discussed for their capacity to remove undesired componnds. Case studies referring to the treatment of ammoniacal etching solntion by SLM, complexation-nltrafiltration conpled with soil washing for soil remediation, volatile organic componnds removal by PV and treatment of tannery wastewaters by MBRs are also presented and discnssed. 

Abstract In this chapter, membrane bioreactors are described from an economic point of view. Economic analysis is a crucial stage in plant design, project and control and also requires an evaluation of the research, development and commercialization of the products and bioproducts. Such an analysis is focused here on membrane bioreactors and reactors, also taking into account the separation units such as micro-, ultra- and nano-flltration units that might be used as a downstream process or as pretreatment steps. The most important rules and parameters are first introduced. Some examples of application and case studies are also reported. 

The economic analysis reported in this chapter with the case studies already described will offer an idea of the methods that can be applied to the project and design of membrane reactors and bioreactors. New investments, as well as the introduction of bioreactors in existing plants, have been taken into account with the aim of offering a general view of their potentialities also from an economic point of view. 

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