Membrane bioreactor plants pilot

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. 

FIGURE 41.2 Flow diagram of the membrane bioreactor pilot plant. 

Operational Data of the Membrane Bioreactor Pilot Plant ... 

From the results obtained in the ultrafiltration membrane bioreactor and reverse osmosis pilot smdies, the industrial plant was designed with the following general characteristics. 

An example of an industrial membrane bioreactor is the hollow-fiber membrane system for the production of (-)-MPGM (1), which is an important intermediate for the production of diltiazem hydrochloride [130, 131]. For the enantiospecific hydrolysis of MPGM a hoUow-fiber ultrafiltration membrane with immobilized lipase from Serratia marcescens is used. (-i-)-MPGM is selectively converted into (2S,3R)-(-i-)-3-(4-methoxy-phenyl)glycidic acid and methanol. The reactant is dissolved in toluene, whereas the hydrophilic product is removed via the aqueous phase at the permeate side of the membrane (see Fig. 5.17). Enantiomerically pure (-)-MPGM is obtained from the toluene phase by a crystallization step. In cooperation with Sepracor Inc., a pilot-plant membrane reactor has been developed, which produces annually about 40 kg (-)-MPGM per m of membrane surface. 

The principal part of the pilot plant comprises a biological reactor (bioreactor) in whose interior the biomass is placed, and two external modules of ultrafiltration membranes placed in series. Figure 41.2 depicts a flow diagram of this pilot plant, which is described in more detail below. 

The pilot plant is equipped with two gauges one at the membrane entrance and the other at the exit. The plant is also equipped with two flowmeters one located at the entrance to the membranes to record the pumped flow and the other in the permeate stream to measure the discharge flow. The plant has a control panel, for starting and stopping the process and for controlling the blower and pump that feeds the bioreactor. The control panel can be set to automatic and the level inside the reactor is kept constant by means of the differential control. 

Escobar et al (2001) did a complete study in which pilot plant trials were conducted in a corn wet mill with a 7000-L membrane recycle bioreactor (MRB) that integrated ceramic microflltration membranes in a semi-closed loop configuration with a stirred-tank reactor. Residence times of 7.5-10 h... 

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