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You hear about an opportunity for a process engineer with acompany that is starting a new commercial plant to produce ethanolfrom hybrid poplar trees. You apply and soon get called for aninterview!

As a good candidate for the position, you do your own searchabout the company before visiting it, and find out that theircurrent process uses direct fermentation of sugars to obtainethanol. They are heavily considering an alternative option,though, which employs fermentation of sugars to acetic acid,followed by hydrogenation of the acetic acid to produce ethanol.The article you read about this only mentions that this alternative“reduces carbon emissions”.

As it turns out, during the interview you are asked to provide adetailed, technical opinion about each one of these two routes.Specifically, you are asked about the challenges involved inseparation: in one case, you need to separate ethanol from waterafter fermentation, in the other case you need to separate aceticacid from water after fermentation. You remember the concepts youlearned in class about multiphase, multicomponent systems andattempts to answer the following questions: How would you design asystem for separation in each case? What type of separation? Whatwould be the challenges involved?

In addition, your response could include other aspects such asthe stoichiometry of each reaction, and potential energyrequirements. Be as quantitative as possible.