Treatment of Pesticide-Contaminated Water Using a Selected Fungal Consortium: Study in a Batch and Packed-Bed Bioreactor

Abstract

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 T1/2 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).

Biodegradation of Iprodione and Chlorpyrifos Using an Immobilized Bacterial Consortium in a Packed-Bed Bioreactor

“…In this study, two bacterial strains were isolated from an organic biomixture of BPS used for pesticide treatment over several years. This organic biomixture contains many active microorganisms and represents an attractive approach because these bacteria have already adapted to interact with high pesticide concentrations [ 8 , 22 , 27 ]. Both bacterial strains used in this study, A. spanius C1 and P. rhodesiae C4, were able to remove high pesticide concentrations of IPR and CHL, and this activity was found to be more effective when both strains were immobilized and used as a consortium.…”

“…Additionally, immobilization enhances cell viability and increases cell tolerance to higher concentrations of pollutants [ 46 ]. In this respect, Ca-alginate beads have been extensively studied for their efficient immobilization of microbial cells due to their low toxicity, ease of use, and low cost [ 22 , 27 ]. Ca-alginate beads act like a slow-release delivery system, where the bacterial cells or their enzymes are slowly released into the medium, enhancing the rate of degradation, tolerance to higher pesticide concentrations, and biomass reusability/recuperation [ 47 ].…”

“…Bacterial strains Achromobacter spanius strain C1 (GenBank accession number: MK110041) and Pseudomonas rhodesiae strain C4 (GenBank accession number: MK110043), previously identified by the 16S rRNA gene [ 14 ], were used in this study. These bacterial strains were previously isolated from BPS used during the last three years for the treatment of commercial IPR and CHL (50 mg kg −1 ) [ 27 ] and were maintained at 4 °C on plate count agar (PCA) containing (per liter) 5 g tryptone, 2.5 g yeast extract, 1 g glucose, and 15 g agar adjusted at pH 7.0. Luria Bertani medium (LB) containing (per liter) 5.0 g NaCl, 5.0 g yeast extract, and 10.0 g casein peptone at pH 7 was used as the culture medium for all evaluations with the individual strains, with the free and immobilized bacterial consortium using a liquid medium.…”

“…The experimental setup for the continuous bioreactor was performed as described by Levio-Raiman et al [ 27 ]. Borosilicate glass columns (5 cm internal diameter, 15 cm length, working volume of 295 mL) were packed with the immobilized bacterial consortium.…”

Biosurfactant Production by Bacillus amyloliquefaciens C11 and Streptomyces lavendulae C27 Isolated from a Biopurification System for Environmental Applications

“…The insecticide CHL, the herbicide atrazine (ATZ), and the fungicide iprodione (IPR) have been widely applied worldwide; they have relatively high chemical and biological stability in soils and aquifers and negative impacts on the environment, human health [ 37 ], and non-target organisms [ 38 ]. These pesticides are commonly used in Chile for the treatment of pests in farming [ 39 ], and their characteristics were reported by Levio et al [ 40 ]. CHL has a low solubility in water (<2 mg L −1 ), whereas IPR and ATZ have solubilities of 6.8 and 35 mg L −1 , respectively.…”