초록
<P><B>Abstract</B></P> <P>Ozone pretreatment of coffee husks (CH) was evaluated to generate hydrolysates for biogas production and to preserve cellulose of the solid phase for 2G ethanol production. Pretreatment variables included liquid-to-solid ratio (<I>LSR</I>), <I>pH</I> and specific applied ozone load (<I>SAOL</I>). Considering single-stage anaerobic digestion (AD), the highest methane production (36 NmL CH<SUB>4</SUB>/g CH) was achieved with the hydrolysate generated in the experiment using <I>LSR</I> 10 mL/g, <I>pH</I> 11 and <I>SAOL</I> 18.5 mg O<SUB>3</SUB>/g CH, leading to 0.064 kJ/g CH energy recovery. Due to the presence of toxic compounds in the hydrolysate, the addition of powdered activated carbon (4 g/L) to the reactor enhanced biogas production, leading to 86 NmL CH<SUB>4</SUB>/g CH yield and 0.58 kJ/g CH energy recovery. When two-stage AD was applied, methane production resulted in 49 NmL CH<SUB>4</SUB>/g CH, with additional 19 NmL H<SUB>2</SUB>/g CH production, resulting in a net 0.26 kJ/g CH energy recovery.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Ozonation of coffee husks (CH) solubilized lignin and hemicelluloses in low severity. </LI> <LI> CH hydrolysates exhibited toxicity towards anaerobic digestion. </LI> <LI> Powdered activated carbon improved methane production in a single-stage process. </LI> <LI> Two-stage anaerobic digestion of CH hydrolysates improved biogas production. </LI> <LI> Biogas burning via CHP system offset the energy expenditure of ozonation. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>