四川某地页岩气压裂返排液处理工艺研究

Study on Treatment Process of Shale Gas Fracturing Flowback Water in Sichuan

页岩气压裂返排液是一种高盐、有机物成分复杂、水质变化范围宽的废水,难以采用单一生化工艺处理。采用“臭氧催化氧化/高铁酸盐氧化+双碱法软化+纳滤膜+反渗透膜”联合处理工艺对该废水进行处理,并研究2种氧化工艺对TOC去除效果,软化和膜法脱盐的效果。结果表明,臭氧催化氧化和高铁酸盐氧化对TOC降解率分别为60%,70%;双碱法软化对Ca^(2+)、Mg^(2+)硬度去除率分别为90.5%,77.8%;膜法脱盐工艺中纳滤对硫酸根拦截率95%,一、二级膜脱盐率分别为99%,95%,工艺出水达到《地表水环境质量标准》(GB 3838—2002)中地表水Ⅲ类水域标准。该联合处理工艺具有一定参考应用价值,可为页岩气压裂返排液达标处理提供参考。

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 Ca^(2+)and Mg^(2+)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.