Efficiently enhanced short-chain fatty acids (SCFAs) recovery from food waste condensate: Real-time wettability monitoring with supported liquid membrane contactor

Food waste condensate (FWC) is a valuable source for recovering short-chain fatty acids (SCFAs) through methods such as supported liquid membrane contactors. Containing organic compounds like acetate, propionate, and butyrate, FWC offers a rich substrate for efficient SCFA extraction. Recovering SCFAs from FWC provides notable environmental advantages, including reducing waste and generating high-value products for industries such as bioenergy and chemical production. This process not only contributes to carbon neutrality by recycling waste streams but also establishes a sustainable method for producing bio-based products from FWC. This study investigated the recovery efficiency and transport mechanisms of SCFAs from SCFA-rich wastewater (e.g., FWC) using both virgin hydrophobic PVDF membranes and membranes filled with organic extractants like tertiary amines (trihexhylamine and trioctylamine) and tertiary phosphines (trihexylphosphine and trioctylphosphine). Recovery efficiency for butyric acid was significantly improved when TOA (trioctylamine) was used, achieving 71.96 %, while acetic acid showed a lower recovery of 0.95 %, highlighting TOA's strong affinity for butyric acid due to ion-amine complex formation. The study also utilized real-time optical coherence tomography (OCT)-based monitoring to observe membrane wetting, finding that the virgin PVDF membrane was more prone to wetting and fouling, with a significant reduction in contact angle and surface energy. In contrast, the PVDF-TOA membrane demonstrated better resistance to wetting, showing minimal changes in contact angle and porosity, underscoring its potential for long-term applications in membrane contactors.