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 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.