Abstract
Minimization of waste, both solid and liquid, is a current goal of the pulp and paper industry. Canada, the United States, Sweden, Finland, Japan, Australia, and Brazil all have relatively stringent environmental regulations governing disposal of wastes from the pulp and paper industry (Owens 1996). The US paper industry generated approximately 5.6 million dry tons of wastewater treatment sludge in 1995 (Lynde-Maas et al. 1997). Of the total reported, 56% was combined primary and secondary sludge, with most of the rest being primary sludge. Primary sludge is the gravity-settled or chemically-coagulated organic and inorganic material derived from untreated mill waste water. Primary sludges often have a solid content of 20–45% which consists of wood fibers, clay, calcium carbonate, titanium dioxide, and other materials used in pulp and paper production, such as inks and dyes (National Council of the Paper Industry for Air and Stream Improvement 1993). Secondary sludges result from the biological treatment of wastewater and contain largely microbial biomass.
Published Version
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