Mineland Reclamation using Office Waste Paper De-Inking Residue

Abstract

Pulp facilities which recycle office waste paper generate a large amount of waste by-products in the process of producing high-grade pulp. The paper-like residue, called de-inking residue, was evaluated for use in the restoration of vegetation on coarse taconite tailings in NE Minnesota. The mineland reclamation rules specify that a 90 percent vegetative cover shall be established on tailings after three growing seasons, however this level of cover on coarse tailings has not been consistently achieved in Minnesota using standard restoration practices. Research plots were established in 1992 at Eveleth Mines arranged in a randomized block design with three replications using five levels of de-inking residue, five levels of fertilization and two plant mixes. A total of twenty-five treatment combinations were assigned to 2.5m- by- 4.0m plots and lysimeters were installed to monitor changes in sub-surface water quality. Coarse tailings were evaluated to determine the effects of de-inking residue on their chemical properties. Vegetative cover was measured in July and September in 1992 and 1993 and nutrient levels were determined in plant samples. Fertilization and de-inking residue amendments had significant effects on the vegetative cover of both introduced and native plant species. De-inking residue had a minimal impact on the chemical properties of coarse tailings at rates up to 80 dry ton/acre and on sub-surface water quality at a depth of four feet. Vegetative cover for introduced species increased from no cover, to 49 percent the first growing season, to 90 percent at the end of the second growing season on tailings fertilized at the highest level and amended with residue at 10 ton/acre. At the same fertilizer and de-inking residue rate, vegetative cover for native plants increased from no cover to 7 percent the first growing season, to 69 percent at the end of the second growing season. Alfalfa had lower levels of boron, magnesium, and manganese on residue amended plots in 1992 and 1993. Bluestem had higher levels of calcium and zinc, but lower levels of magnesium and manganese on residue amended. plots. Cadmium, chromium, copper, nickel, lead, and zinc in alfalfa and bluestem did not accumulate to toxic levels. Deinking residue appears to have benefited vegetative growth after two growing seasons using deinking residue applied at 10 dry ton/acre with fertilizer applied at 160 lb/acre of nitrogen and 359 lb/acre of phosphorus.