页岩压裂返排液的预处理及絮凝剂的溶液结构

Pre-treatment of the fracturing flow-back fluid of shale and solution structures of a flocculant

页岩压裂返排液因含有多种有机添加剂,其化学需氧量较高。本文研究了新型无机复合混凝剂聚硅酸铝铁(PCM)对废水的混凝效果及与其复配使用的梳型絮凝剂(4-乙烯苄基辛基酚聚氧乙烯醚)-丙烯酰胺-(2-丙烯酰胺基-2-甲基丙磺酸钠)共聚物(PAVA)的絮凝能力,以提高页岩压裂返排液的预处理效率。结果显示,PCM在其加量0.3g/L时的浊度和COD去除率分别为96.1%和71.4%,明显高于常用的聚合氯化铝PAC的水处理性能值;PCM与5mg/L PAVA复配使用后,其用量明显降低,但处理效果更好,加量为0.2g/L时的浊度和COD去除率分别为90.0%和86.1%;PAVA的架桥絮凝能力强于常用的阴离子、阳离子高分子絮凝剂;返排液中ξ电位的绝对值越高,混凝剂的混凝效果越好。

The chemical oxygen demand value is high for the fracturing flow-back solution of shale containing a few organic additives.This paper studied the coagulation effect of a novel inorganic compound coagulant polysilicate aluminum ferric(PCM)and the flocculation properties of a comb-like polymer flocculant poly[(p-vinyl benzyl po1yoxyethylene octylphenol ether)-acrylamide-(sodium2-acrylamido-2-methylpropane sulphonate)](PAVA)combined with PCM.The objective was to enhance the pre-treating efficiency for fracturing flow-back fluid of shale.Then some results were obtained.When the dosage of PCM alone was at 0.3g/L,the removal efficiencies of turbidity and COD were 96.1%and 71.4%,respectively.These data were obviously higher than those using the typical polyaluminum chloride(PAC).When PCM was used together with PAVA at 5mg/L,the PCM dosage decreased markedly but the treating efficiency was higher.For example,when the dosage of PCM was at 0.2g/L,the removal efficiencies of turbidity and COD were up to 90.0%and 86.1%,respectively.The bridging flocculation effect was stronger for PAVA than for typical anionic and cationic polymer flocculants.The higher theξ-potential value was in the flow-back fluid,the higher the coagulation efficiency was.