Evaluation of electrochemical and O₃/UV/H₂O₂ methods at various combinations during treatment of mature landfill leachate

Abstract

In this study, electrochemical treatment and application of O₃/UV/H₂O₂ in various combinations were evaluated in respect to their efficiency to depurate mature landfill leachate. Based on preliminary experiments, electrochemical treatment using stainless-steel electrodes at 2 cm gap was performed optimally at 50 mA/cm² and pH 6, while application of O₃ at 120 L/h, UV at 991 J/cm² and H₂O₂ concentration of 1 g/L was carried out. Electrochemical treatment and O₃/UV/H₂O₂ under optimal conditions were applied as follows: I) electrochemical treatment, followed by O₃/UV/H₂O₂ and solids precipitation, II) electrochemical treatment, followed by precipitation and then by O₃/UV/H₂O₂ treatment, and III) O₃/UV/H₂O₂, followed by electrochemical treatment. A low performance was observed when O₃/UV/H₂O₂ preceding electrochemical treatment. Solids, TKN and total COD (tCON) removal was primarily achieved through electrocoagulation, whereas color and soluble COD (sCOD) reduction was mainly attributed to electrochemical oxidation. Experimental setup I was the most efficient treatment scheme, resulting in tCOD, sCOD, TKN, TSS, SAC_UV254nm and color number reduction of 73%, 80%, 76%, 79%, 94% and 98%, respectively. Indeed, O₃/UV/H₂O₂ step could be omitted since its effectiveness was restricted during landfill leachate treatment. In conclusion, electrochemical treatment followed by precipitation could result in effective reduction of nutrients and color.

Keywords:

• Mature landfill leachate
• electrochemical oxidation
• electrocoagulation
• advanced oxidation processes
• O₃/UV/H₂O₂

Funding

The author(s) reported there is no funding associated with the work featured in this article.

Data availability statement

The authors confirm that the data supporting the findings of this study are available within the article.