Análise das rotas de valorização aplicáveis a lodos da indústria de papel e celulose sob a perspectiva da economia circular

Abstract

The pulp and paper industry generates large volumes of wastewater sludge from effluent treatment plants, the management of which represents an environmental and economic challenge for the sector. In this context, the valorization of these materials emerges as an alternative to expand resource recovery and promote practices aligned with the principles of the circular economy. This work aimed to perform a comparative evaluation of technological routes for the valorization of fibrous sludge from the pulp and paper industry, seeking to analyze the alignment of different material and energy recovery alternatives based on a real case study. The methodology consisted of an integrated literature review and a case study based on the characterization data of a biosolid generated in a pulp and paper industrial unit and reported by Zangalli (2024). The different valorization routes identified in the literature were compared using an evaluation matrix based on criteria related to sludge composition, moisture content, technological maturity, environmental compliance, logistical feasibility, and value-added potential. The results showed that the studied biosolid presents a high moisture content (75.93%), a high organic fraction (70.74%), the presence of remaining fibers, and metal concentrations compatible with current environmental legislation. The comparative analysis indicated that the recovery of degraded areas route adopted by Zangalli (2024) shows high suitability to the material's profile, especially by allowing the direct use of the sludge without the need for additional drying, favoring nutrient recycling, and meeting applicable environmental requirements. Additionally, it was found that the high organic fraction and the presence of fibers provide potential for applications associated with the biorefinery concept, including the production of biofuels, bioproducts, and materials derived from cellulosic fibers. In contrast, thermochemical routes presented limitations mainly associated with the high moisture content of the biosolid. It is concluded that the recovery of degraded areas route constitutes a technically compatible alternative with the sludge characteristics and the operational reality of the analyzed unit. However, the results also demonstrate that the biosolid has potential for other higher value-added valorization strategies, which demand complementary studies of technical, economic, and environmental feasibility for their future implementation.