Toxicity of paper mill pelletized waste using germination and biomass production as bioindicators

Abstract

The use of wood residues to produce energy and steam in the pulp

and paper industry generates ash waste and sewage sludge that contain nutrients for plants

as a potential fertilizer. The objective of this study was to evaluate the possible toxic effects

of pelletized waste from the pulp and paper industry using bioindicators. Two controlled

experiments were conducted with radish seeds and perennial ryegrass seeds: an experiment

to determine the germination index and root growth in soil extracts incubated with pelletized

waste, and a pot experiment with ryegrass seeds sown in an amended Alfisol with pelletized

wastes in which aerial and root biomass production was determined. The results indicate that

the Alfisol amended with pelletized waste did not exhibit any acute or sub-acute toxic effects

in radish germination. None of the evaluated pellets showed evidence of deterioration in root

elongation, including at a 40 Mg ha-1 dose. The highest root growth was with pellet 2, with

ash and sludge at the 40 Mg ha-1 dose, which was higher than that in the control treatment

(p<0.05). Seed germination was between 93.9% and 100%. The highest ryegrass aerial biomass

occurred with pellets 1 and 2 (p<0.05). Pelletized waste from the paper industry exhibited

neither mild nor acute effects of toxicity in both radish seed germination and aerial and root

biomass production of ryegrass sown in degraded soil.