Fig. 3

Simplified illustration of liquid flows for in situ adsorption and Raman analysis for the different phases of product separation cycles. A schematic drawing of the complete experimental setup with all pumps and valves is shown in Additional file 1: Figure S7. Tanks are filled with DI-water (dark blue), waste (green), ethanol (light blue) and product solution (red). Flow directions during different steps: A fermentation: bioreactor → Raman sensor 1 → bioreactor. B Washing: water tank → adsorption column → Raman sensor 2 → waste tank (fermentation step is run simultaneously). C Water displacement: bioreactor → Raman sensor 1 → adsorption column → Raman sensor 2 → waste tank. D Adsorption: bioreactor → Raman sensor 1 → adsorption column → Raman sensor 2 → bioreactor. E Broth displacement: ethanol tank → adsorption column → Raman sensor 2 → bioreactor. F Desorption: ethanol tank → adsorption column → Raman sensor 2 → product tank (fermentation step is run simultaneously)