Granulation of Paper Residues with Wood Ash and Evaluation of Greenhouse Gas Emissions

The granulation of biosolids such as wood ash (WA), deinking paper sludge (DPS), and mixed paper sludge (MPS) is an innovative solution to encourage the use of waste residues instead of landfilling, which is responsible for high greenhouses gases emissions (GHG). A comprehensive characterization of pellets' physicochemical properties was carried out to evaluate their fertilizing potential and conformity to international standards. An incubation study investigated the effect of these pellets on carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) acidic soil emissions. This study evaluated the potential of these pellets to mitigate GHG. We investigated eight pellet formulations: unfertilized, fertilized with mineral nitrogen, and six pelleted alkaline organic residue amendments combined with mineral nitrogen fertilizer. Pellets made from composted DPS and DPS showed improved durability and density. These residues acted as a bonding agent to enhance the pellets' cohesion. Pellets made from composted DPS and WA released 10% less CO2 than the other pellets. At the same time, DPS, MPS, and WA pellets reduced the NO2 emissions by 40%. Thus, pellets made from the paper biosolid residues and wood ash are an attractive source of organic matter for forestry and agricultural soils and the attenuation of GHG emissions.