Thiamethoxam removal by Fenton and biological oxidation

Abstract

BACKGROUND Thiamethoxam (TMX) is a potential insecticide pollutant of hydric resources that must be removed. Advanced oxidation processes (AOPs) are usually effective, but expensive to implement. Combining Fenton's reagent with biological oxidation circumvents the shortcomings of Fenton technology, facilitating the biodegradation of the resulting effluents in a sequencing batch reactor (SBR). RESULTS Fenton‐like oxidation of TMX with variable hydrogen peroxide (H2O2) doses afforded total organic carbon (TOC) conversion and chemical oxygen demand (COD) removal by (respectively) 40% and 80% from pure TMX, and 40% and 60% from commercial TMX. The effluents from Fenton oxidation using substoichiometric H2O2 doses were less ecotoxic and more biodegradable than the initial solution and, therefore, susceptible to a biological treatment. Biological oxidation of effluents obtained from 50% and 75% H2O2 doses was accomplished for different organic loads in 6‐h cycles. Coupling Fenton and biological oxidation of TMX afforded TOC conversion and COD removal of 80% for the effluent obtained with a 75% H2O2 dose. CONCLUSIONS Coupling Fenton–biological oxidation efficiently reduces the amounts of H2O2 needed and produces biodegradable effluents. In addition, the biological treatment increases COD and TOC removal by ≤80% for the overall treatment. © 2019 Society of Chemical Industry

Advanced catalytic oxidation coupled to biological systems to treat pesticide-contaminated water: A review on technological trends and future challenges

“…Also, an uncontrolled increase in peroxide doses can inhibit the generation of OH radicals (Chen et al 2007) as also reported in (Gomez-Herrero et al 2020). One aspect to highlight that has not been discussed in previous research is that the Fe2þ dose influences the reaction rate of the Fenton process, as reported by (Chen et al 2007), however, a concentration that does not affect bacterial growth must be guaranteed (Ballesteros Martín et al 2008a, 2008b, so optimizing this parameter in the experimental design contributes to significant improvements in the advanced oxidation process.…”

Recent trends in treatment technologies of emerging contaminants

“…In a study performed by Gomez‐Herrero et al. (2020), the removal of the pure and commercial insecticide thiamethoxam (TMX) by Fenton‐like and Fenton‐biological oxidation was explored. For pure TMX, the Fenton process decreased the chemical oxygen demand (COD) by 80% and the total organic carbon (TOC) by 40%, while for commercial TMX, the COD and TOC reduction were 60% and 40%, respectively.…”

“…In a study performed by Gomez-Herrero et al (2020), the removal of the pure and commercial insecticide thiamethoxam (TMX) by Fentonlike and Fenton-biological oxidation was explored. For pure TMX, the Fenton process decreased the chemical oxygen demand (COD) by 80%…”

In Focus: 7th European Bioremediation Conference (EBCVII)

“…The latter seems to be more effective and has the potential for scale‐up applications. Another approach regarding the biodegradation of emerging pollutants was demonstrated by Gomez‐Herrero et al ., who worked with thiamethoxam (TMX), which is the first pesticide of the second generation of neonicotinoids . This group tested the performance of a combined Fenton–biological treatment for the removal of this pesticide from aqueous solutions.…”

“…Another approach regarding the biodegradation of emerging pollutants was demonstrated by Gomez-Herrero et al, who worked with thiamethoxam (TMX), which is the first pesticide of the second generation of neonicotinoids. 3 This group tested the performance of a combined Fenton-biological treatment for the removal of this pesticide from aqueous solutions. Coupling those methods improved substantially the removal rates, while also limited down ecotoxic effects.…”