A NOVEL AND VALUABLE STRATEGY FOR SUSTAINABLE ENERGY PRODUCTION THROUGH THE GASIFICATION OF PULP AND PAPER MILL SLUDGE

Pulp and paper mill sludge (PPMS) is the main processing waste of the pulp and paper industry. PPMS is a carbon-based material, generally divided into primary and secondary sludge, generated from wastewater treatments. The current management and disposal of these different forms of solid waste are landfilling and/or incineration, incurring economic, environmental and social costs that will surely increase in the future. The present work concerns the use of primary PPMS as low-value feedstock for the production of high-quality syngas for energy recovery. In this context, oxy-gasification has been proposed as an alternative and efficient valorisation method. The experimental activity was conducted in a downdraft fixed bed reactor (≈100 KwTH) adopting a mixture of O2/H2O as a gasifying agent, and a mixture of PPMS and wood pellets in a ratio of 1:5 wt/wt. The adopted conditions allowed good quality nitrogen-free syngas characterised by high H2 (40 mol%) and CO (21 mol%) content and high values of Cold Gas Efficiency (CGE). Moreover, the characterization of gasification side products, such as ash and tar, has been also performed, revealing that the ash predominantly consisted of CaO. On the other hand, tar compositional analysis, performed through GC-MS, evidenced the presence of long-chain hydrocarbons (C19-C39) and polyaromatics.