Method and system for producing products by fermentation

A method for producing solvents by fermentation, said method comprising the steps of:

• performing a first fermentation step by fermenting a feedstock in the presence of microorganisms forming a first product stream;
• performing a pervaporation step on the first product stream forming a permeate;
• performing a first condensation step by partially condensing the permeate forming a first condensate and a residue stream, wherein the first condensation step is performed at a first pressure being below atmospheric pressure;
• performing a second condensation step by condensing the residue stream at a second pressure higher than the first pressure forming a second condensate;
• distilling the second condensate to produce a stream enriched in a first range of solvents and a liquid stream depleted in the first range of solvents;
• and
• decanting the first condensate together with the liquid stream forming a phase enriched in a second range of solvents and an aqueous phase.