Study of woody fibre in papermill sludge

grantor: University of TorontoIn order to determine the role that papermill sludge plays in the organic carbon cycle of the forest products industry, a global model of sludge generation has been created. Analysis of mixed sludge output of six Ontario papermills derived fundamental data on the characteristics of sludge. A methodology to identify and quantify the woody organic material present in the sludge matrix was developed. The wood chemical composition of the woody organic fraction of each sludge stream was investigated. The results of physical and chemical testing were then compared to validate the proposed methodology. On the basis of this analysis, mill outputs were divided into three categories related to mill parameters. The physical properties of sludge fibres were found to be linked to the presence or absence of recycled fibres, and showed little correlation to the pulping technique or recovery method employed. The chemistry of the organic fraction of sludge was found to be more closely related to mill process. It is shown that the basic holocellulose and lignin compositions follow a normal distribution for each of the three mill categories. Sludges produced at primary installations, which use primarily virgin fibre, were found to have the largest component of woody organic material. Recycling and deinking operations had a lower proportion of fibre in the sludge stream. In order to understand global patterns of papermill sludge production, trends in paper and paperboard production, consumption, and recovery were analyzed and projected until the year 2050. Parameters used in describing trends included population parameters (size, density, and literacy rate), as well as fibre supply parameters (forest, plantation, and nonwood fibre supply). The model accounted for 80% of paper consumption, 94% of paper production, and 96% of paper recycling at high correlation coefficients. A major shift in the global pattern of sludge production is predicted, with Asia emerging as the second largest sludge-producing region. Global production of papermill sludge will rise to 4,800,000 metric tons in 2050. The fraction of sludge material deriving from wood fibres will decline, reducing potential for fibre recovery and lowering the possible contribution of sludge towards carbon sequestering.Ph.D