Enhancement of biodegradation capacity of microbial consortium in non-thermal plasma post-discharge for the removal of azo dye Reactive Red 120
摘要
The presence of emerging contaminants in wastewater remains a hot topic of environmental concern due to their persistence, even at low concentrations. Biological treatment appears as an easy technique to implement, but its efficiency could decrease face to the recalcitrant pollutants. Therefore, this study aimed to investigate the synergistic effect between the Gliding arc plasma (Glidarc) and biodegradation (using a microbial consortium) routes for the degradation of Reactive Red 120 (RR120), as the model pollutant organic dye. Three bacterial species, including Staphylococcus aureus, Escherichia coli and Vibrio cholerae, were isolated on the surface waters, and combined into a consortium. RR120 (50–200 mg L−1) inhibited the microbial growth of each bacterial specie (until 99% for S. aureus at 4.2 × 109 CFU mL−1, 82% for E. coli at 6.8 × 109 CFU mL−1, 72% for V. cholerae at 8.0 × 106 CFU mL−1). Treatment using the consortium alone degraded 58% of RR120 (50 mg L−1) after 24 h of incubation, with a first-order kinetic constant of 0.032 h⁻1. To enhance this biological performance, RR120 solution was pre-treated using glidarc plasma for short times (5 and 10 min), resulting in an increase in the BOD5/COD ratio, which leading to the increase of the biodegradability. Under plasma post-discharge conditions with the microbial consortium, the biodegradation rate of RR120 reached 89% after 24 h of incubation, with a kinetic constant of 0.080 h⁻1. The biodegradation mechanism suggests that the process is initiated by the adsorption (approximately 34%), followed by microbial metabolism. This work shows that the microbial metabolism is significantly facilitated (catalysed) under plasma post-discharge conditions and highlights the economic benefit of the coupling both processes.