含油废水分离与处理技术研究进展

Research Progress on Separation and Treatment Technology of Oily Wastewater

摘要: 油田开发过程中产生的大量含油废水是石油工业最主要的废水来源之一，其中油田采出水具有水量大、成分复杂、盐度高以及油类污染物赋存形态多样等特点。随着油田进入中后期开发阶段以及聚合物驱、表面活性剂驱等提高采收率技术的应用，采出水中乳化油、聚合物、表面活性剂及溶解性有机污染物含量和组成更加复杂，传统单一除油技术面临越来越明显的局限。本文围绕油田含油废水的污染特征和处理难点，系统总结重力分离、水力旋流、气浮、混凝破乳等传统物理化学处理技术，并重点分析膜分离技术在微细油滴和乳化油去除中的优势以及油污染、孔堵塞和滤饼层形成等膜污染问题。在此基础上，对吸附、生物处理及高级氧化等深度处理方法进行比较。研究表明，传统物理化学方法工程成熟度高，适合作为含油废水预处理及主体除油单元；微滤和超滤等膜技术具有分离精度高、出水水质稳定和设备紧凑等优势，是乳化油深度分离的重要发展方向，但其长期运行仍受到膜污染和清洗成本限制。吸附、生物及高级氧化则主要用于残余油类和溶解性有机污染物的进一步去除。针对实际油田采出水成分复杂、单一技术难以兼顾除油、降解有机物和回用要求的问题，未来研究应由单纯提高瞬时去除率转向提高材料抗污染性、耐盐性和长期稳定性，同时强化物理分离、生物降解和高级氧化等多技术耦合，并从末端污染治理进一步向原油回收、废水净化和水资源循环利用方向发展。

Abstract: A large volume of oily-wastewater generated during oilfield development is one of the primary wastewater sources in the petroleum industry. Among such wastewater, oilfield produced water is characterized by high volume flow, complex composition, high salinity, and diverse occurrence forms of oily pollutants. As oilfields enter the mid to late development stage and enhanced oil-recovery technologies such as polymer flooding and surfactant flooding are applied, the content and composition of emulsified oil, polymers, surfactants and dissolved organic pollutants in produced water have become more complicated, and conventional single oil removal technologies are confronted with increasingly prominent limitations. Focusing on the pollution characteristics and treatment difficulties of oilfield oily wastewater, this paper systematically summarizes traditional physicochemical treatment technologies including gravity separation, hydrocyclone separation, air flotation and coagulation demulsification, and emphatically analyzes the advantages of membrane separation technology in removing fine oil droplets and emulsified oil, as well as membrane fouling problems such as oil contamination, pore clogging and filter-cake layer formation. On this basis, advanced-treatment methods including adsorption, biological treatment and advanced-oxidation processes are compared. The research results indicate that traditional physicochemical methods boast high engineering maturity and are suitable to serve as pretreatment and main oil-removal units for oily-wastewater; membrane technologies such as microfiltration and ultrafiltration feature high separation precision, stable effluent quality and compact equipment, representing an important development direction for deep separation of emulsified oil, while their long term operation is still restricted by membrane fouling and cleaning costs. Adsorption, biological treatment and advanced-oxidation processes are mainly adopted for further removal of residual oil pollutants and dissolved organic contaminants. In view of the problem that single technologies can hardly satisfy the requirements of oil removal, organic matter degradation and water reuse given the complex composition of actual oilfield-produced water, future research should shift from merely improving instantaneous removal efficiency to enhancing the fouling-resistance, salt-tolerance and long term stability of materials. Meanwhile, the coupling of multiple technologies such as physical separation, biodegradation and advanced oxidation should be strengthened, and the development trend should shift from end of pipe pollution control toward crude oil recovery, wastewater purification and water resource recycling.