Landfill leachate is a complex and variable wastewater rich in organic matter, ammonium, salts, and metals, with low biodegradability and highly fluctuating composition. Its management still largely relies on energy- and chemical-intensive treatment schemes, making the treatment of raw, undiluted landfill leachate particularly challenging. This study evaluates, at lab scale, the potential of aerobic granular sludge (AGS) for achieving simultaneous pollutant removal and metal recovery in a 2-L column sequencing batch reactor fed with raw, undiluted landfill leachate collected from an active municipal landfill site. The reactor was operated for 198 days without dilution or addition of co-substrates. This operation resulted in stable granulation and high removal efficiencies, 94% for chemical oxygen demand (COD) and 97% for total nitrogen. Cation analysis shows that assimilation reached 600.47 µmol g⁻¹ TS, with calcium and magnesium being the predominant cations. Quantitative analyses revealed near-equal contributions from biosorption (53%) and bioaccumulation (47%), with magnesium dominating biosorption and calcium prevailing in bioaccumulation. Then, a partial metal recovery was achieved by desorption with 0.1 M NaCl, without compromising the granule structure, as verified by FTIR and scanning electron microscopy (SEM). However, the desorption process reduced nitrification and denitrification activities by factors of 3.7 and 1.8, respectively, while heterotrophic activity increased by 2.4-fold. Metagenomic analysis revealed microbial shifts following desorption, favouring genera such as Paracoccus and Burkholderia, which are associated with heterotrophic metabolism. These results demonstrate the potential of AGS as a regenerative biosorbent for treating landfill leachate and recovering metals. This approach supports sustainable and circular strategies for managing landfill leachate and similar complex effluents.

The increasing presence of heavy metals such as copper (Cu ²⁺ ) in aquatic environments poses major risks to ecosystems and public health. Conventional wastewater treatment systems are typically inefficient at recovering valuable metals and rarely integrate circular economy principles, leading to resource loss and secondary pollution. This study evaluates the feasibility of using partial nitrification–Anammox granular sludge as a regenerable biosorbent for Cu ²⁺ recovery under mild conditions. Biosorption experiments were conducted under controlled conditions, with approximately 70% of the initially added copper retained by the granules. Desorption was optimized by using sodium chloride (NaCl) as a benign, low-impact alternative to conventional acidic eluents, reaching equilibrium within 60 min and following pseudo-second order kinetics. The maximum experimental design desorption efficiency was 36% under the evaluated conditions, without significant changes in granule morphology. Metabolic activity analysis showed an ∼87% decrease in specific nitrifying activity after copper exposure, followed by a complete loss of activity after saline desorption. In contrast, specific Anammox activity decreased by nearly three-fold but remained functional after desorption. Reusability tests over five biosorption–desorption cycles demonstrated consistent copper removal (∼60% of influent Cu ²⁺ ) and average desorption efficiencies of ∼60% of the retained copper during cyclic operation, without visible deterioration of the granular structure. These results contribute to the understanding of metal recovery using microbial granules and offer a foundation for the development of integrated strategies that combine nitrogen removal and copper capture in wastewater treatment systems based on sustainable economy.