Separation of Volatile Fatty Acids by Simulated Moving Bed

This work evaluated the feasibility of the simulated moving bed (SMB) technology to fractionate volatile fatty acids produced through wastewater acidogenic fermentation. A lab-scale SMB unit equipped with 6 columns (FlexSMB), each packed with a nonfunctionalized resin (Amberlite XAD-4), was used to separate a binary solution of acetic and propanoic acids, for proof of concept. SMB operating conditions were first determined by building the separation region for a limit purity of 95% in both extract and raffinate streams, and a 1-2-2-1 column configuration. The process accomplished the separation of acetic and propanoic acids in the raffinate and extract streams, with purities of 97.8% and 100.0%, and recoveries of 100.0% and 97.8%, respectively. Productivities reached 2.93 and 2.81 mmol·g_ads ^-1.day^-1 in the raffinate and extract streams, respectively. An eluent consumption of 0.075 L·mmol^-1 was attained. The mathematical model proposed accurately described the experimental data. Overall, SMB technology showed strong potential for efficient VFA fractionation.