Guard multiple operators

The use of various membrane configurations coupled with bioreactors has lead to multiple functionality improvements and innovations. Implementation as guard beds, recycle conditioning vessels (with solids separations capabilities), in situ extraction systems, and slipstream (and bypass) reactors for biocatalyst activity maintenance, are but a few important examples representing successful applications when using living systems operating in controlled microenvironments. 

The functioning of the multiple-layer protection system can be summarized as follows (AIChE, 1993) Most failures in well-designed and operated chemical processes are contained by the first one or two protection layers. The middle levels guard against major releases and the outermost layers provide mitigation response to very unlikely major events. For major hazard potential, even more layers may be necessary. ... 

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