Pelletized paper mill waste promotes nutrient input and N mineralization in a degraded Alfisol

Abstract

Pulp and paper mill waste, such as biomass fly ash and sewage sludge, is commonly disposed of in landfills. This waste can be valuable as nutrients and C sources for degraded soils. Ash and sludge samples were chemically characterized before ash/sludge pellets were experimentally manufactured for use as soil amendment. An incubation experiment was carried out with controlled moisture and temperature; nutrient input and N mineralization were evaluated at 0, 15, 30, 45, and 60 d intervals using three pellet types with different proportions of ash, sludge, and gypsum (as a binder) and applied at four doses equivalent to 0, 10, 20, and 40 Mg ha -1 . Results indicated that the Alfisol that was amended with pelletized residues increased P Olsen and exchangeable K and Ca contents, as well as soil pH (p < 0.05) in direct response to the applied doses. Organic matter decreased during incubation at all the doses and pellet types (p < 0.05); however, N mineralization did not show a clear pattern during incubation. Nitrogen mineralization potential (N 0 ) was different depending on pellet types and application rates; Pellet 2 (10% sludge) exhibited the highest N 0 values, while Pellet 3 (20% sludge) had lower N 0 than the control. Pulp and paper mill waste can be used to amend degraded soils by creating sustainable use through pelletizing because it facilitates transport and can evenly distribute sludge and ash on soils in a single application.

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

“…Some plant species or populations are sensitive to abiotic stress or can be tolerant and show small inhibitions in germination or development in primary stages (Gvozdenac et al, 2016;Mekki et al, 2017). However, synergetic effects of doses and pellet types in our study generated positive effects in radicle elongation, GI, and radish seed germination (Table 2), similar to those found by Undurraga et al (2017) with pellet 2 that presented the best response in incubation experiments of a degraded Alfisol, estimating that a proportion of sludge of 10% is more adequate (Table 1).…”

“…The chemical parameters of pulp and paper mill waste used in pellet fabrication contained elements that could contribute to increased fertility in degraded soils; moreover, pellet pH was high (8.16), helping to reduce soil acidity and improve levels of nutrients, such as Ca, Mg, and K, during applications to soil (Undurraga et al, 2017). The metals analyzed in bottom and fly ashes, with pellets fabrications, had high concentrations of Al, Si, and Ti, being the elements with the greatest Table 2.…”

“…Additionally, pulp and paper mill waste can be used to amend degraded soils and to create their sustainable use. In addition, pelletizing facilitates transport and requires only a single application to evenly distribute sludge and ashes on soil that needs to be amended (Undurraga et al, 2017). The hypothesis is that the application of pelletized amendments composed of ash and sludge from the paper industry has a toxic effect on crops.…”