Assessment of Earthworm Viability and Soil Health after Two Years of Raw and Composted De-Inking Paper Sludge Amendment

Abstract

The improvement of soil fertility properties is a priority for meeting sustainable development goals and world food security. One potential benefit of using paper sludge in agriculture is the reduction of waste and associated environmental impacts. By using paper sludge as a soil amendment, it is possible to divert away this material from landfills and instead use it to improve soil fertility and support the growth of crops. However, it is important to note that paper sludge may contain contaminants harmful to plants and soil health, of which earthworm viability serves as a key indicator. The present investigation aimed to evaluate changes in soil properties after the application of raw and composted de-inking paper sludge for two years. Accordingly, a field study was conducted in Manouba, a semi-arid region of Tunisia with a clay loam soil. The raw de-inking sludge (DS) and composted de-inking paper sludge (DSC) were applied at 30 and 60 t ha−1 and 20 and 40 t ha−1, respectively. Soil treatments were compared to unamended soils (C), to determine the optimal sludge treatment and rate for increasing the soil quality. Soil chemical (soil organic matter SOM, total carbon TC, and nitrogen TN, nutrient soil contents organic matter fractioned), physical (porosity and structural stability), and biological parameters (earthworms viability) were assessed. The results showed an increase of soil OM in the DS and DSC amended soils with the lowest rates (30 and 20 t ha−1). The humic fraction was found to be the dominant form. TC and TN were improved in the DS and DSC amended soils with the highest rates: 60 (DS2) and 40 t ha−1 (DSC2). Phosphorus and potassium were also increased in a dose-dependent manner. However, the soil porosity decreased in all treatments. The composted de-inking sludge was toxic for epigeic species, which could be explained by the use of litter while composting. Overall, the application of DS and DSC at low rates (30 and 20 t ha−1, respectively) might be a promising alternative for improving soil quality and at the same time ensuring the proper management of these wastes.

Utilizing de‐inked paper sludge for sustainable production of medium‐density fiberboard: A comprehensive study

“…Among the various waste streams in papermaking, DPS is a major concern due to its large volume and limited disposal options. 1 The quantity of DPS produced during pulp and paper production can vary depending on factors such as the type of pulp used, the production process, and waste management practices. 2 Recent studies have provided insights into DPS generation during the production of recycled fibers.…”

“…The potential reuse of DPS has been investigated in a range of products, including wood-based panels, 9,10 clay bricks, 11 cement composites, 12,13 woodplastic composites, 7,8 particleboard, 10,14,15 fiberboard, 9,16 pallets, 6 and compost. 1 However, the varying properties of DPS can pose challenges to recycling and reuse. The physical and chemical properties of DPS depend on the type and quality of cellulosic materials, additives, pulping methods, and their efficiency.…”

“…However, this process generates a substantial amount of solid waste known as de‐inked paper sludge (DPS). Among the various waste streams in papermaking, DPS is a major concern due to its large volume and limited disposal options 1 . The quantity of DPS produced during pulp and paper production can vary depending on factors such as the type of pulp used, the production process, and waste management practices 2 .…”

“…The effective recycling of paper sludge is crucial for the sustainable development of the pulp and paper industry, both economically and environmentally. The potential reuse of DPS has been investigated in a range of products, including wood‐based panels, 9,10 clay bricks, 11 cement composites, 12,13 wood‐plastic composites, 7,8 particleboard, 10,14,15 fiberboard, 9,16 pallets, 6 and compost 1 . However, the varying properties of DPS can pose challenges to recycling and reuse.…”