A detailed bifurcation/chaotic investigation of a single continuous fermentor using an experimentally verified model was published earlier by the authors (Chem. Eng. Sci. 58 (2003) 1479); the present paper is an extension of the earlier one. It uses the same biokinetic model to investigate the effects of continuous ethanol removal using permselective membranes, cell recycle with varying cell separation efficiencies and recycle of unused sugars for two configurations of fermentors. The rich static/dynamic bifurcation and chaotic behavior of two different configurations are investigated. The aim is to gain deeper understanding of the complex static/dynamic characteristics of this system as a prelude to a detailed experimental investigation. The emphasis is on achieving higher sugar conversion, ethanol yield and productivity through the exploitation of these characteristics and optimal manipulation of operating and design parameters within the bifurcation/chaotic regions. (C) 2004 Elsevier Ltd. All rights reserved.