Biorefineries process bioresources such as agriculture or forest biomass to produce energy and a wide variety of precursor chemicals and bio-based materials, similar to the modem petroleum refineries. Industrial platform chemicals such as acetic acid, liquid fuels such as bioethanol and biodegradable plastics such as polyhydroxyalkanoates can be produced from wood and other lignocellulosic biomass. Biorefineries use a variety of separation methods often to produce high value co-products from the various feed streams. In this paper, a critical review of separation methods and technologies related to biorefining including pre-extraction of hemicellulose and other value-added chemicals, detoxitication of fermentation hydrolyzates, and ethanol product separation and dehydration is presented. For future biorefineries, extractive distillation with ionic liquids and hyperbranched polymers, adsorption with molecular sieve and bio-based adsorbents, nanofiltration, extractive-fermentation, membrane pervaporation in bioreactors, and vacuum membrane distillation (VMD) hold significant potential and great promise for further investigation, development and application. (c) 2008 Elsevier B.V. All rights reserved.