Volatile fatty acids (VFAs) are widely used chemicals, which serve as precursors for e.g., polymers. These VFAs can be produced through unsustainable petrochemical routes. Fermented wastewater provides a sustainable source of these VFAs, however the concentration of these small acids is low. We use complex coacervates to extract VFAs from the wastewater. Complex coacervates are liquid-like phases consisting of oppositely charged polyelectrolytes. We have successfully extracted acetic and butyric acid. The only problem is that it is difficult to recover the acids from these liquids. Complex coacervates with acids have a different viscosity and are optically less transparent than "empty" complex coacervates. We think that this is due to a change of the structure of this dense phase. SANS will help us to understand these changes and help us to find an sustainable way to recover the acids.