In this study, we selected and characterized different pesticide-tolerant bacteria isolated from a biomixture of a biopurification system that had received continuous applications of a pesticides mixture. The amplicon analysis of biomixture reported that the phyla Proteobacteria, Firmicutes, Bacteroidetes and Actinobacteria were predominant. Six strains grew in the presence of chlorpyrifos and iprodione. Biochemical characterization showed that all isolates were positive for esterase, acid phosphatase, among others, and they were identified as Pseudomonas, Rhodococcus and Achromobacter based on molecular and proteomic analysis. Bacterial growth decreased as both pesticide concentrations increased from 10 to 100 mg L^-1 in liquid culture. The Achromobacter sp. strain C1 showed the best chlorpyrifos removal rate of 0.072–0.147 d^-1 a half-life of 4.7–9.7 d and a maximum metabolite concentration of 2.10 mg L^-1 at 120 h. On the other hand, Pseudomonas sp. strain C9 showed the highest iprodione removal rate of 0.100–0.193 d^-1 a half-life of 4–7 d and maximum metabolite concentration of 0.95 mg L^-1 at 48 h. The Achromobacter and Pseudomonas strains showed a good potential as chlorpyrifos and iprodione-degrading bacteria.

This study provides the basis for implementing a continuous treatment system for wastewater containing a pesticide mixture formed by atrazine, iprodione, and chlorpyrifos. Two fungal strains (Verticilium sp. H5 and Metacordyceps sp. H12) isolated from a biomixture of a biopurification system were able to remove different pesticide concentrations (10 to 50 mg L⁻¹) efficiently from the liquid medium; however, the half-life of the pesticides was reduced and characterized by a T_1/2 of 5.4 to 9.2 d for atrazine, 3.7 to 5.8 d for iprodione, and 2.6 to 2.9 d for chlorpyrifos using the fungal consortium. The immobilization of the fungal consortium in alginate bead was effective, with the highest pesticide removal observed using an inoculum concentration of 30% wv⁻¹. The packed-bed reactor with the immobilized fungal consortium, which was operated in the continuous mode at different flow rates (30, 60, and 90 mL h⁻¹), required approximately 10 d to achieve removal efficiency (atrazine: 59%; iprodione: 96%; chlorpyrifos: ~85%). The bioreactor was sensitive to flow rate fluctuations but was able to recover performance quickly. The pesticide metabolites hydroxyatrazine, 3,5-dichloroaniline, and 3,5,6-trichloro-2-pyridinol were produced, and a slight accumulation of 3,5,6-trichloro-2-pyridinol was observed. Nevertheless, reactor removal efficiency was maintained until the study ended (60 d).