Evaluation of a new pulping technology for pre-treating source-separated organic household waste prior to anaerobic digestion

• Published in: Waste management (Elmsford) 2016-04, Vol.50, p.65-74
• Main Authors: Naroznova, Irina, Møller, Jacob, Larsen, Bjarne, Scheutz, Charlotte
• Format: Article
• Language: English
• Subjects: Anaerobic digestion; Anaerobiosis; Biochemical methane potential; Biodegradability; Biofuels - analysis; Biomass; Bioreactors; Hazardous substances; Household wastes; Mass balance; Materials recovery; Methane - analysis; Pre-treatment; Pretreatment; Pulping; Refuse Disposal; Source-separated organic household waste; Waste Management - methods; Wastes
• ISSN: 0956-053X; 1879-2456
• DOI: 10.1016/j.wasman.2016.01.042

•A new technology for pre-treatment of source-separated organic household waste was assessed.•A mass balance including biopulp for biogas production and reject was established.•Transfer of substances to biopulp including nutrients and heavy metals was determined.•Material loss and biodegradable material in reject was small compared to other technologies.•Content of hazardous substances in the biodegradable material fractions was important. A new technology for pre-treating source-separated organic household waste prior to anaerobic digestion was assessed, and its performance was compared to existing alternative pre-treatment technologies. This pre-treatment technology is based on waste pulping with water, using a specially developed screw mechanism. The pre-treatment technology rejects more than 95% (wet weight) of non-biodegradable impurities in waste collected from households and generates biopulp ready for anaerobic digestion. Overall, 84–99% of biodegradable material (on a dry weight basis) in the waste was recovered in the biopulp. The biochemical methane potential for the biopulp was 469±7mL CH4/g ash-free mass. Moreover, all Danish and European Union requirements regarding the content of hazardous substances in biomass intended for land application were fulfilled. Compared to other pre-treatment alternatives, the screw-pulping technology showed higher biodegradable material recovery, lower electricity consumption and comparable water consumption. The higher material recovery achieved with the technology was associated with greater transfer of nutrients (N and P), carbon (total and biogenic) but also heavy metals (except Pb) to the produced biomass. The data generated in this study could be used for the environmental assessment of the technology and thus help in selecting the best pre-treatment technology for source separated organic household waste.