Phycoremediation of ten sulfonamide antibiotics in swine wastewater: Microalgal tolerance, toxicity, and carbohydrate-rich biomass production

This study investigates the removal of ten sulfonamide antibiotic residues from swine wastewater using Chlorella spp. in a phycoremediation process. The effects of sulfonamides on microalgal biomass production, pigment content (chlorophyll α, chlorophyll b, and carotenoids), and the genotoxicity of treated water were evaluated. Sulfonamides were tested at concentrations of 0.1, 1.0, 10, 50, and/or 100 mg L⁻¹ , with the antibiotic removal specifically assessed at 10 mg L⁻¹ . Results showed that Chlorella spp. exhibited robust biomass growth and maintained stable pigment production, even at the highest concentrations, indicating the microalgae's tolerance to antibiotic exposure. The removal efficiency for sulfonamides was notably high, particularly for sulfamethoxazole (70 %), sulfachlorpyridazine (55 %), and sulfamerazine and sulfamethizole (50 %) at the 10 mg L⁻¹ concentration. Genotoxicity assays with Allium cepa revealed minimal chromosomal aberrations, suggesting that the treated wastewater posed a low genotoxic risk. The microalgal biomass, characterized by high carbohydrate content, also holds promise for biofuel production. These findings highlight Chlorella spp. as an effective and sustainable solution for mitigating antibiotic pollution in agricultural wastewater, while simultaneously providing valuable biomass for renewable energy applications.