Elsevier

Water Research

Volume 138, 1 July 2018, Pages 47-55
Water Research

Removal of organic compounds from shale gas flowback water

https://doi.org/10.1016/j.watres.2018.03.041Get rights and content
Under a Creative Commons license
open access

Highlights

  • Organic matter in flowback water is dominated by low molecular weight fractions.

  • Low molecular weight organics are effectively removed via biodegradation.

  • Organics with high molecular weight are targeted by activated carbon.

  • Biodegradation and activated carbon may complement flowback desalination.

Abstract

Ozonation, sorption to granular activated carbon and aerobic degradation were compared as potential treatment methods for removal of dissolved organic carbon (DOC) fractions and selected organic compounds from shale gas flowback water after pre-treatment in dissolved air flotation unit. Flowback water was characterised by high chemical oxygen demand and DOC. Low molecular weight (LMW) acids and neutral compounds were the most abundant organic fractions, corresponding to 47% and 35% of DOC respectively. Ozonation did not change distribution of organic carbon fractions and concentrations of detected individual organic compounds significantly. Sorption to activated carbon targeted removal of individual organic compounds with molecular weight >115 Da, whereas LMW compounds remained largely unaffected. Aerobic degradation was responsible for removal of LMW compounds and partial ammonium removal, whereas formation of intermediates with molecular weight of 200–350 Da was observed. Combination of aerobic degradation for LMW organics removal with adsorption to activated carbon for removal of non-biodegradable organics is proposed to be implemented between pre-treatment (dissolved air floatation) and desalination (thermal or membrane desalination) steps.

Keywords

Shale gas
Hydraulic fracturing
Flowback water
Dissolved organic carbon
Aerobic degradation

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