Study on screening and degradation pathways of PMT substances in volume fracturing flowback water

Objective This study aims to identify the persistent, migratory and toxic (PMT) high-risk substances in the organic pollutants of shale oil volume fracturing flowback water and explore their degradation-transformation pathways.

Method The organic components in the flowback water from fracturing were analyzed by gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-mass spectrometry (LC-MS) techniques. Based on the BioWIN model prediction and threshold analysis method, PMT substances were screened out.

Result Six PMT substances were screened out from the fracturing flowback water. Such as Triethyl phosphate, Tributyl phosphate, Dibutyl Phosphate, Naphthalene, 1-Methyl naphthalene, 2-Methyl naphthalene. After being treated with Fe²⁺-activated percarbonate (SPC) oxidation, the persistence and biological toxicity of the typical PMT substances were significantly reduced.

Conclusion The Fe²⁺/SPC oxidation technology can effectively reduce the environmental risks of PMT substances, providing technical support for the treatment and risk prevention of the flowback water from shale oil fracturing.