Comprehensive characterization of landfill-bound paper waste from non-recycled municipal solid waste for sustainable...

Paper waste (PW) is a major biodegradable component of non-recycled municipal solid waste (NMSW), yet it is predominantly landfilled despite its potential for material and energy recovery. This study introduces a composition-informed classification framework that categorizes PW into four distinct groups: high-cellulose (HC), high-lignin (HL), high-ash (HA), and highly contaminated (HCon) papers. This framework links material properties with suitable valorization pathways. Ten PW samples were collected across seasons to capture feedstock variability and subjected to comprehensive physicochemical and thermal characterization, including moisture content, bulk density, carbohydrate composition, proximate and ultimate analyses, thermal degradation behavior, and higher heating value (HHV). Results show that HC was the most abundant fraction, representing 37 % of PW, with up to 61 % glucan and approximately 7 % acid-insoluble residue, indicating potential suitability for enzymatic hydrolysis. HL papers exhibited relatively low moisture content (approximately 11.4 %), high carbon content (approximately 43 %), and the highest dry-basis HHV (approximately 17.1 MJ kg^-1), indicating favorable fuel characteristics for thermochemical conversion. HA samples contained elevated ash associated with pigments and fillers, whereas HCon papers showed the highest moisture content, approximately 35 %, supporting composting or hydrothermal carbonization pathways. Homogenization increased bulk density threefold and reduced particle-size variability, improving handling and downstream process compatibility. Overall, 41 % of PW was technically recyclable and 56 % was compatible with composting, while hydrothermal carbonization was identified as an additional pathway for high-moisture fractions, underscoring the untapped potential of landfill-bound paper waste for circular material and energy systems.