An efficient system of aerogel adsorbent combined with membranes for reuse of shale gas wastewater

The internal reuse of shale gas flowback and produced water (SGFPW) can ease the pressure on treatment and management costs and freshwater supply. Internal reuse of SGFPW based on membrane treatments is faced with major challenges of the divalent ion and organic pollutant removal as well as membrane fouling control. To solve these problems, a green and efficient adsorbent of porous biochar aerogel (PBA) was combined with ultrafiltration (UF)-nanofiltration (NF) for SGFPW internal reuse in this study. The removal performance of dissolved organic carbon (DOC, >85.9%) and divalent ions (>70.6%) for three SGFPW showed feasibility of PBA-UF-NF process for internal reuse. Three-dimensional excitation-emission matrix (3D EEM) fluorescence spectrum, organic fractionation and the extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) theory were used to identify the organic composition of SGFPW and analyze membrane fouling. PBA tended to adsorb hydrophobic fraction and alleviated UF membrane fouling caused by attractive hydrophobicity. NF membrane fouling was mitigated due to the increased polar repulsion as well as the decreased synergistic fouling between organics and divalent cations through the reduction of DOC by PBA. PBA-UF-NF process had good performance on organic pollutant and divalent ion removal with decreasing membrane fouling, presenting potential to treat SGFPW onsite for internal reuse.