1 Recovery of Volatile Fatty Acids from Anaerobic Acidification Broth by Liquid-Liquid Extraction Emrah Alkaya 1 , Serkan Kaptan 1 , Leyla Ozkan 1 , Sibel Uludag-Demirer 2 , Göksel N. Demirer 1* 1 Department of Environmental Engineering, Middle East Technical University, Inonu Bulvari, 06531, Ankara, Turkey, 2 Department of Industrial Engineering, Cankaya University, 06530 Ankara, Turkey ABSTRACT In this study, anaerobic acidification of sugar beet processing wastes and subsequent liquid-liquid extraction of produced fermentation metabolites were investigated. The aim of extraction experiments was to asses the influence of pH and extractant (TOPO in kerosene) concentrations on the recovery of VFAs from fermentation broth. The effect of TOPO in kerosene concentration was as crucial as the effect of pH on the recovery of VFAs via extraction. Consequently, pH 2.5 was determined as optimum. At this pH, percent recoveries of VFAs were changed from 43.3 to 97.6%, depending on the type of the acid extracted (acetic, butyric, propionic and valeric acids) and the concentration of TOPO in kerosene (5–20%). As the concentration of TOPO in kerosene was increased, efficiency of extraction was increased. As a result, highest VFA recoveries (60.7–97.6%) were observed at 20% TOPO in kerosene with K D values ranging between 1.54 and 40.79. At pH 2.5, the increase in TOPO concentration directly increased the COD removal efficiencies, as it does for tVFA recovery. Up to 71.8% COD removals were achieved, at 20% TOPO in kerosene at pH 2.5, while the removal efficiencies remained between 19.1– 22.3% at pH 5.5. Keywords: Anaerobic acidification, Fermentation, Volatile fatty acids, Liquid-liquid extraction, Chemical oxygen demand removal * Corresponding author. Phone: +90-312-210 58 67, Fax: +90-312 210 26 46, E-mail: goksel@metu.edu.tr