Study on Treatment Process of Shale Gas Fracturing Flowback Water in Sichuan
The shale gas fracturing flowback water is a high-salt,complex organic,wide water quality range,and difficult to adopt a single biochemical process to treat.The "ozone catalytic oxidation/ferric hydroxide oxidation+double alkali softening+nanofiltration membrane+reverse osmosis membrane" combined treatment process is used to treat the wastewater,and studies the effects of the two oxidation processes on TOC removal,softening and membrane desalination.The results show that ozone catalytic oxidation and ferric hydroxide oxidation have TOC degradation rates of 60%and 70%respectively;the double alkali softening method has hardness efficiency for Ca2+and Mg2+of 90.5%and 77.8%respectively;the membrane desalination process,nanofiltration,has a sulfate interception rate of 95%,and the demineralization rates of the first and second membranes are 99%and 95%respectively.The process outlet water meets the standard of surface water environment quality standard(GB 3838-2002)for surface water class III waters.The combined treatment process has certain reference application value and can provide reference for the standard treatment of shale gas fracturing flowback water.