Biosurfactant-facilitated biodegradation of hydrophobic organic compounds in hydraulic fracturing flowback wastewater: A dose-effect analysis

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 -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. (c) 2020 Elsevier B.V. All rights reserved.