Removal of refractory organic pollutants in reverse-osmosis concentrated leachate by Microwave–Fenton process
2018
Zhang, Aiping | Gu, Zhepei | Chen, Weiming | Li, Qibin | Jiang, Guobin
A microwave–Fenton technology was applied to dispose of the reverse-osmosis concentrated leachate. Influential factors on the treatment of concentrated leachate with the pure Fenton and microwave-Fenton method were investigated. For the conventional Fenton process, the removal efficiencies of chemical oxygen demand (CODCᵣ), UV₂₅₄, and the color number (CN) reached 84%, 87%, and 96%, respectively, with the biodegradability (BOD₅/CODCᵣ) increased from 0.13 to 0.51 at an initial pH of 5.0, Fe²⁺ of 0.04 mol/L, a n(H₂O₂)/n(Fe²⁺) ratio of 8 after a reaction time of 3 h. When incorporating the Fenton process with microwave irradiation, a comparative CODCᵣ and UV₂₅₄, and the CN removal rate of 75%, 83%, and 95%, and a high BOD₅/CODCᵣ of 0.62 were achieved under a microwave power of 390 W and an extremely shortened reaction time of only 8 min. Meanwhile, sludge quantity showed a reduction of 24.7%, decreased from 8.50 g/L to 6.40 g/L after the participation of microwave. In addition, molecular-weight fraction (MWF), UV-visible spectrum (UV-vis), and 3D-EEM spectrum tests demonstrated that the macromolecular and complex organic compounds in the wastewater were significantly decomposed into small molecular matters. Our results found that microwave–Fenton is a promising technology for concentrated leachate treatment, with much shorter reaction time, lower sludge production, and enhanced biodegradability, as well as comparative organic matter removal performance.
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