초록
<P><B>Abstract</B></P> <P>In this study a two-steps bioprocess approach aimed at biohydrogen production via dark-fermentation, and polyhydroxyalkanoates-PHA production by mixed microbial cultures, was proposed to valorise two dairy-waste streams coming from cheese whey deproteinization (i.e. <I>Ricotta</I> cheese production and ultrafiltration). During the first step, the increase of OLR was tested, resulting in higher daily H<SUB>2</SUB> volume (3.47 and 5.07 NL H<SUB>2</SUB> d<SUP>−1</SUP> for second cheese whey-SCW and concentrated cheese whey permeate-CCWP) and organic acids production (14.6 and 12.6 g L<SUP>−1</SUP> d<SUP>−1</SUP> for SCW and CCWP) for both the substrates, keeping good conversion of sugars into H<SUB>2</SUB> (1.37 and 1.93 mol H<SUB>2</SUB> mol<SUP>−1</SUP> sugars for SCW and CCWP). During the second step, the organic acids were used for PHA production reaching high conversion yields for both the fermented streams (as average 0.74 ± 0.14 mg COD<SUB>PHA</SUB> mg<SUP>−1</SUP> COD<SUB>OA-in</SUB>), with a maximum polymer content of 62 ± 4.5 and 55.1 ± 1.3% (g PHA g<SUP>−1</SUP> VSS) for fermented SCW and fermented CCWP respectively. For the results reported, this study could be taken into consideration for larger scale application.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Deproteinized cheese whey wastes (DCW) still contain valuable molecules, i.e. sugars. </LI> <LI> Sugars can be used to produce H2 and organic acid (OAs) by dark fermentation. </LI> <LI> OAs can be used to produce polyhydroxyalkanoates (PHA) by mix microbial culture. </LI> <LI> This two-cascade approach can be used to valorize DCW producing high value molecule. </LI> </UL> </P>