초록
<P><B>Abstract</B></P> <P>In the present work, the enhancement of biogas and methane yields through anaerobic co-digestion of the pre-hydrolised Organic Fraction of Municipal Solid Wastes (hOFMSW) and Maize Cob Wastes (MCW) in a lab-scale thermophilic anaerobic reactor was tested. In order to increase its biodegradability, MCW were submitted to an initial pre-treatment screening phase as follows: (i) microwave (MW) irradiation catalysed by NaOH, (ii) MW catalysed by glycerol in water and alkaline water solutions, (iii) MW catalysed by H<SUB>2</SUB>O<SUB>2</SUB> with pH of 9.8 and (iv) chemical pre-treatment at room temperature catalysed by H<SUB>2</SUB>O<SUB>2</SUB> with 4 h reaction time. The pre-treatments cataysed by H<SUB>2</SUB>O<SUB>2</SUB> were performed with 2% MCW (wMCW/v alkaline water) at ratios of 0.125, 0.25, 0.5 and 1.0 (wH<SUB>2</SUB>O<SUB>2</SUB>/wMCW). The pre-treatment that presented the most favourable balance between sugars, lignin, cellulose and hemicellulose solubilisations, as well as low production of phenolic compound and furfural (inhibitors), was the chemical pre-treatment catalysed by H<SUB>2</SUB>O<SUB>2</SUB>, at room temperature, with a ratio of 0.5 wH<SUB>2</SUB>O<SUB>2</SUB>/wMCW (Pre1). This Pre1 was then optimised testing reaction times of 1, 2 and 3 days at a different pH (11.5) and MCW percentage (10% w/v). The optimised pre-treatment that presented the best results, considering the same criteria defined above, was the one carried out during 3 days, at pH 9.8 and 10% MCW w/v (Pre2).</P> <P>The anaerobic reactor was initially fed with the hOFMSW obtained from the hydrolysis tank of an industrial AD plant. The hOFMSW was than co-digested with MCW submitted to the pre-treatment Pre1. In another assay, hOFMSW was co-digested with MCW submitted pre-treatment Pre 2. The co-digestion of hOFMSW + Pre1 increased the biogas yield by 38.9% and methane yield by 29.7%, when compared to the results obtained with hOFMSW alone. The co-digestion of hOFMSW + Pre2 increased biogas yield by 46.0% and CH<SUB>4</SUB> yield by 36.3%. In both cases, the methane content obtained in the biogas streams was above 66% v/v. These results show that pre-treatment with H<SUB>2</SUB>O<SUB>2</SUB>, at room temperature, is a promising low cost way to valorize MCW through co-digestion with hOFMSW.</P> <P><B>Highlights</B></P> <P> <UL> <LI> H<SUB>2</SUB>O<SUB>2</SUB> pre-treatment increases MCW digestibility with low inhibitors formation. </LI> <LI> The use of MW in MCW pre-treatment with H<SUB>2</SUB>O<SUB>2</SUB> do not arise significant benefits. </LI> <LI> MCW pre-treated with H<SUB>2</SUB>O<SUB>2</SUB> with high reaction time causes some inhibition of AD. </LI> <LI> Co-AD of MCW with OFMSW allows significant enhancement of biogas and methane yields. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>