Real herbicide wastewater treatment by combined means of electrocatalysis application and biological treatment

ABSTRACT

In this study, the real herbicide wastewater was degraded by electrocatalysis oxidation followed by subsequent biological treatment. The influence of several process variables of electrocatalysis oxidation, such as current density, pH and electrode gap on chemical oxygen demand (COD) removal ratio, was investigated and the optimum conditions were determined. The results indicated that COD removal ratio reached 87.0%, and the COD decreased from 7519 mg L⁻¹ to 980 mg L⁻¹ after 120 min electrolysis under the degradation parameters of the current density of 4 a dm⁻², pH value of 4 and the plate spacing of 1.0 cm. The electrocatalysis degradation of real herbicide wastewater followed pseudo-first-order kinetics. The BOD₅/COD increased from 0.18 to 0.43 after 120 min electrolysis. Then, the biological contact oxidation process was performed on the effluent of the electrochemical process. The results showed that the final COD removal ratio reached 95.8% after biological contact oxidation on the following condition: hydraulic residence time was 12 h and the aeration quantity was 0.6 m³ h⁻¹. Conclusively, it can be proved that electrocatalysis is feasible as a pre-treatment technology to treat real herbicide wastewater.

KEYWORDS:

• Electrochemistry
• Operational parameters
• Combined treatment
• Biological contact oxidation
• Real herbicide wastewater

Notes on contributors

Yingwu Yao had worked in the Environmental Protection Bureau for many years. He is currently a professor at the Hebei University of Technology and his expertise falls under the domain of environmental pollution control. He has more than 25 publications to his credit in reputed international journals and he handled several scientific projects.

Feng Wei is currently a professor at the Hebei University of Technology. His research focuses on chemical environmental engineering. His main research content is equipment design, which has made great contributions to the design of experimental equipment in this work.

Liman Zhang is a master student in Chemistry at the Hebei University of Technology. Her area of research is wastewater treatment processes. Besides she finished all the testing and analysis in the study.

Qiang Zhao is currently finalising his master degree at the Hebei University of Technology with skills and expertise in electrochemical engineering.

Shuang Lv is a master student in Chemistry at the Hebei University of Technology. His major is environmental engineering.

ORCID

Feng Wei http://orcid.org/0000-0003-3698-5844

Yingwu Yao http://orcid.org/0000-0003-0715-3598

Additional information

Funding

This work was supported by the National Natural Science Foundation of China under Grant [21576065, 21402038]. The authors want to thank the National Natural Science Foundation of China for the financial support which made this study possible.