A novel process was proposed for treating heavily polluted hydraulic fracturing flowback water from oil/gas production with an initial chemical oxygen demand (COD) of 8850 mg/L. The process was comprised of gel breaking, cavitation-impinging stream/iron-carbon micro-electrolysis (CIS/ICME) and electro-Fenton. The viscosity of the wastewater was reduced from 6.20 to 1.09 mPa•s after 90 min of gel breaking treatment using sodium hypochlorite at a dosage of 3.0 g/L. The CIS technology solved the passivation and hardening problems of traditional ICME technology, enhancing COD abatement by 48.2% points and increasing iron utilization from 36.8% to 82.4%. The results show that, under the optimum conditions, the effluent COD was reduced to around 170 mg/L with a removal efficiency of 98.1%, and the reduction ratios of oil, color, corrosion rate and suspended solids reached 100%, 95.2%, 94.0% and 97.7%, respectively. The quality of final effluent could meet the national discharge standard of China. The CIS/ICME process removed a considerable proportion of COD and oil, while the electro-Fenton unit played an important role in post-polish of final effluent. This study shows that the hybrid system has the potential to be applied for the advanced treatment of high-strength oilfield wastewater.

提出了一种处理油/气生产中重污染水力压裂返排水的新工艺，初始化学需氧量（COD）为8850 mg/L。该工艺由凝胶破裂、空化冲击流/铁碳微电解（CIS/ICME）和电芬顿组成。使用剂量为 3.0 g/L 的次氯酸钠进行 90 分钟的破胶处理后，废水的粘度从 6.20 降至 1.09 mPa•s。CIS技术解决了传统ICME技术的钝化和硬化问题，COD降低48.2个百分点，铁利用率从36.8%提高到82.4%。结果表明，在最佳条件下，出水COD降低至170 mg/L左右，去除效率达98.1%，油、色、腐蚀率和悬浮物分别达到100%、95.2%、94.0%和97.7%。最终出水水质达到国家排放标准。CIS/ICME 工艺去除了相当一部分的 COD 和油，而电芬顿装置在最终出水的后抛光中发挥了重要作用。该研究表明，该混合系统具有应用于高浓度油田废水深度处理的潜力。