Comparison of ozone-based AOPs on the removal of organic matter from the secondary biochemical effluent of coking wastewater

ABSTRACT

Advanced oxidation processes (AOPs) based on ozone are gaining continuously growing popularity in wastewater treatment. This study explored the treatment of coking wastewater using a combination of ozonation (O₃), ultraviolet (UV), and hydrogen peroxide (H₂O₂) process expressed by % chemical oxygen demand (COD) removal, % total organic carbon (TOC), % UV₂₅₄, % fluorescence intensity removal and its electrical energy consumption. The obtained results demonstrated that, the combination of O₃, UV, and H₂O₂ which is denoted by O₃/UV/H₂O₂ in this study achieved great success in COD removal (92.08%), TOC removal (78.25%), and reduction of fluorescence intensity (99.82%). Compared with the O₃ and O₃/UV processes, O₃/UV/H₂O₂ improved the COD removal by approximately 54–69% and 38–51%, respectively. In addition, the energy consumption was reduced by 53–67%. The TOC removal rate in the effluent ranged 71% and 83%, while the UV₂₅₄ removal rate was up to 90%. The fluorescence spectroscopy showed that the O₃/UV/H₂O₂ combination process reduced the fluorescence intensity by almost 97% within 10 min. Furthermore, the total polycyclic aromatic hydrocarbons (PAHs) concentration in the effluent was less than 10μg/L (removal efficiency > 80%) and the most toxic benzo(a)pyrene (BaP) was less than 0.03 μg/L (0.018μg/L). In addition, the energy consumption of the O₃/UV/H₂O₂ process was 53–67% lower than those of O₃ and O₃/UV processes. Furthermore, the energy consumption was 80.26 kWh m⁻³ after 60 min of reaction time when the COD (69.3 mg/L) met the standard discharge. Finally, the O₃/UV/H₂O₂ process could be an effective method for improving the mineralisation of refractory organic matter.

GRAPHICAL ABSTRACT

KEYWORDS:

• Advanced oxidation processes
• Ozone-based process
• Organic matter
• Coking wastewater
• Fluorescence spectroscopy

Acknowledgements

Yuxian Ji: Conceptualisation, Methodology, Investigation, Validation, Formal analysis, Data curation, Writing-original draft, Writing-review & editing, Visualisation. Chunrong Wang: Conceptualisation, Methodology, Resources, Data curation, Writing – original draft, Writing-review & editing, Visualisation, Supervision. Lei He: Conceptualisation, Methodology, Investigation, Validation, Formal analysis, Data curation. Xiaoya Chen: Investigation, Validation, Resources, Formal analysis, Data curation. Jianbing Wang: Investigation, Validation, Formal analysis, Data curation. Xian Zhang: Investigation, Validation, Formal analysis, Data curation, Project administration, Funding acquisition. Qingbang Du: Conceptualisation, Methodology, Writing-review & editing, Visualisation.

Disclosure statement

No potential conflict of interest was reported by the author(s ).

Data availability statement

The data used in the current study are available from the corresponding author on reasonable request.

Additional information

Funding

The research is supported by the project (NO. 5216007).