Feasibility of the batch fermentation process of Ricotta Cheese Whey (RCW)

The aim of the present work is to investigate the feasibility of bio-ethanol production by batch fermentation of Ricotta Cheese Whey (RCW). RCW is a dairy industry waste characterized by lactose concentration ranging from 4.5% to 5.0% (w/w) and by a lower protein content compared to the raw whey. This relatively high lactose concentration makes RCW a potential effective non-vegetable source for renewable energy production. The microorganism used to carry out the fermentation processes was the yeast Kluyveromyces marxianus. Preliminary experiments, performed in aerobic conditions on different volumes of RCW, have shown the actual growth of the yeast. The subsequent fermentation experiments were carried out, in anaerobic conditions, on three different substrates: RCW, raw cheese whey and deproteinized whey. The experimental data have demonstrated that RCW is an excellent substrate for fermentation and exhibits better performance (i.e. ethanol yield) with respect to both raw cheese whey and deproteinized whey. Complete lactose consumption, indeed, was achieved in considerably short time (13 hours) and with the highest ethanol yield (97% of the theoretical value). These results are clearly demonstrate process feasibility at labscale, which encourages further evaluation and optimization of the process in pilot and full-scale studies.