Thermally Dried Sewage Sludge: A Solution for Circular Economy and Sustainable Agriculture
DOI:
https://doi.org/10.47941/je.3396Keywords:
Thermally Dried Sewage Sludge, Circular Economy, Nutrient Recycling, Biosolids, Sustainable AgricultureAbstract
Purpose: To evaluate the physicochemical composition, nutrient profile, and regulatory compliance of thermally dried sewage sludge (DSS) produced at a full-scale wastewater treatment plant in southern Brazil, assessing its potential for agricultural reuse within circular economy frameworks.
Methodology: A 12-month monitoring campaign was conducted from November 2022 to October 2023. Monthly DSS samples were collected post-thermal drying (300 °C, 50 min) and analyzed for moisture, volatile matter, ash, pH, total organic carbon (TOC), macronutrients (P, K, Ca, Mg), nitrogen fractions (TKN, TAN), and heavy metals regulated by Brazilian standards.
Findings: Moisture content varied widely (1.35–30.61%), influenced by seasonal precipitation. Volatile matter and ash averaged 44.91% and 38.85%, respectively, while TOC averaged 20.45%. Phosphorus (2.03–2.49%) and calcium (1.07–1.35%) were present at agronomically relevant levels, whereas potassium remained low (0.08–0.15%). All heavy metals complied with national thresholds, except for one isolated zinc exceedance (8,800 mg·kg⁻¹). Overall, DSS demonstrated suitability for agricultural application under regulated conditions.
Unique Contribution to Theory, Practice and Policy: This study provides the first comprehensive dataset on thermally dried sewage sludge in Brazil, supporting its safe reuse as a nutrient source and reinforcing circular economy strategies in the sanitation sector. The findings offer a scientific basis for policy development and biosolids valorization, contributing to sustainable waste management and resource recovery.
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Copyright (c) 2025 Gabriele Kuhn Dupont, Marco Aurélio da Silva Carvalho Filho, Carlos Itsuo Yamamoto, Gustavo Rafael Collere Possetti
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