Contaminants, biochemical methane potential, and biodegradability of different bio-waste categories: guidance for...

This study evaluated the anaerobic digestion suitability of bio-waste from different sources by comparing their biochemical methane potential (BMP), biodegradability (BI), and content of contaminants (heavy metals and physical impurities) - an often-overlooked factor but one of particular concern in bio-waste. Predominant heavy metals included Cu and Zn, while recurring physical impurities comprised plastics and organic non-biodegradable matter. Food waste from food processing plants were most suitable, exhibiting low contamination and high biogas conversion (BMP > 549 NmLCH₄/gVS and BI > 86 %). Conversely, organic fractions from mechanical biological treatment were highly contaminated, while green waste displayed low biogas conversion (BMP < 368 NmLCH₄/gVS and BI < 72 %). Food waste from households and medium/large-sized producers also demonstrated high biogas conversion, but variable contamination levels could compromise their suitability. Assessing contaminants alongside BMP and BI provides a comprehensive approach for selecting suitable bio-waste feedstocks that can be introduced in biogas plants.