Modeling the role of papermill sludge in the organic carbon cycle of paper products
Fundamental information about the chemistry of sludge, published rates of sludge generation, and models of paper production and wastepaper recycling were combined to create a predictive model. The goal of the modeling exercise was to determine and project global sludge production until the year 2050. It was predicted that a global shift in paper and paperboard production would result in the Asia-Pacific region emerging as a major producer of papermill sludge. Global production of papermill sludge was predicted to rise over the next 50 years by between 48 and 86% over current levels. Sludge was found to contain a large amount of woody organic material, but the proportion of this material in the sludge was found to drop as recycling programs were implemented. Sludge was also found to contain a large amount of woody carbon, which comprised about 30% of the total sludge solids. The presence of such a large proportion of woody carbon may become important if a system of carbon crediting is implemented for the forest industry. Key words: carbon cycle, forests, papermill sludge, modeling, life cycle analysis.