Waste Paper Sludge-An Update on Current Technology and Reuse

Waste paper sludge, or fiber-clay as it if often identified when used as a resource for recycling and reuse in new applications, has over the last several years become a vital component in several geotechnical uses and a variety of manufactured products. Among the major reuses of fiber-clay has been its use as a cover material for sanitary landfills, after thorough laboratory and field evaluations. Because of the high kaolin clay content in the manufacturing of paper products, there is a high residual of clay in waste paper sludge from the manufacturer's waste water treatment plants. The reuse for cover material has resulted in a cost avoidance for the waste generator, reducing or eliminating disposal costs as well as eliminating the need for finding a disposal site. There are also cost savings for landfill operators and owners who otherwise would have to secure an adequate clay source. When compacted, most fiber-clays exhibit adequate hydraulic conductivity and shear strength for use in landfill covers. In addition to its use as a cover material, the fiber-clay, when combined with a pozzalonic material such as fly ash and aggregate, has been used as one of the major components of road beds, both as subsurface base and as a finished surface for remote access and secondary roads. Additional uses include the manufacturing of kitty litter and animal bedding. This paper will review the history and technology involved in evaluating the potential uses of fiber-clay. Extensive laboratory and field testing has been done to determine its shear strength, slope stability, hydraulic conductivity, and settlement potential. Information is presented on the various testing techniques and results, together with examples of actual field projects.