Self-supporting electrodes have triggered great interests in improving electro-Fenton (EF) system for degradation of refractory organic pollutants . In this work, a novel self-supporting carbon fiber paper (CFP) electrode modified by transition metals, e.g. Fe and Mn, was fabricated and employed as a heterogeneous EF cathode. The prepared electrode exhibited excellent degradation for a number of typical organic pollutants along with superior stability. Remarkably, a high removal efficiency was achieved in the EF treatment of shale gas fracturing flowback wastewater. Results indicated that 65.2% TOC and 74.8% COD were eliminated after 4 h degradation. The residual COD value of the real wastewater was 80 mg L −1 , meeting the emission requirement of the integrated wastewater discharge standard (COD ＜ 100 mg L −1 ) with a low specific energy consumption of 6.9 kWh kg −1 COD −1 . This work demonstrates a competing alternative for efficient decontamination of real wastewater using an electro-Fenton strategy with a low-cost electrode.
In this work, efficient Fenton strategy have been proposed for degradation of shale gas fracturing flow-back wastewater using the spherical Fe/Al 2 O 3 supported catalyst. Prior to actual fracturing fluid treatment, the typical model wastewaters such as p -nitrophenol and polyacrylamide were employed to evaluate the catalytic properties of prepared catalyst, and then Fenton treatment of the shale gas fracturing flow-back wastewater was performed on the self-assembled catalytic degradation reactor for continuous flow purification. Results showed that under the conditions of 0.25 mol L −1 impregnating concentration, pH 4, 50 g L −1 catalyst and 0.75 mL L −1 30% H 2 O 2 , the removal efficiency of p -nitrophenol and polyacrylamide reached 74% and 61%, respectively, while the COD removal of fracturing flow-back fluid was approximately 48% with the residual 88 mg L −1 COD, meeting the emission standards of the integrated wastewater discharge standard (GB 8978-1996, COD < 100 mg L −1 ). This work offers new alternatives for Fenton treatment of real wastewater by efficient and low-cost supported catalysts.
This work investigated the effects of biosurfactant at varied dose on the bioremediation of hydraulic fracturing flowback wastewater (HFFW) and explored the associated mechanism. Initially, a biosurfactant-producing strain Pseudomonas sp. CH1 was isolated from oily sludge . The glycolipid biosurfactant produced by CH1 have a critical micelle concentration (CMC) of 80 mg/L, and showed high stability over a wide range of temperature (0–120 °C), pH (4–12), and salinity (0%–16%, w/v). Addition of sub-CMC dose of biosurfactant to HFFW greatly enhanced the microbial growth and activity, upregulated the expression levels of degradation-related genes, and effectively promoted the biodegradation of n -alkanes (reduction from 272.21 to 56.93 mg/L) and PAHs (reduction from 61.6 to 16.36 μ g/L) in 7 days. The results suggested the feasibility of applying biosurfactant with sub-CMC dose to remediate HFFW and contribute significantly to the optimization of surfactant-facilitated bioremediation strategies.
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