Production of Volatile Fatty Acids from Cheese Whey and Their Recovery Using Gas-Permeable Membranes

The use of anaerobic fermentation to produce volatile fatty acids (VFAs) is an environmentally sustainable alternative for cheese whey (CW) valorization. This study evaluates the effect of pH control on the conversion of organic matter to VFAs from CW and assesses VFA recovery using a novel approach based on gas-permeable membranes. VFA bioconversion and composition were studied with initial and sequential control of pH, both in acidic and alkaline conditions. Bioconversion efficiencies for assays with initial pH control were 36% and 45% for acidic and alkaline conditions, respectively. Sequential control of pH resulted in an increase in bioconversion to 54% under acidic conditions. Under acidic conditions, a variety of VFA was produced (mainly butyric, acetic, and propionic acids), while under alkaline conditions the majority was acetic acid. VFA recovery using a novel system of tubular gas-permeable membranes accounted for 15% and 100% of the total VFA from effluent 1 (butyric, acetic, and propionic acids) and effluent 2 (mainly acetic acid), respectively.