电脱盐废水电絮凝破乳分离机制及工艺优化  

Mechanism and process optimization of electrocoagulation for desalter wastewater demulsification separation

作　　者：张华 吴百春 张晓飞 刘译阳 毛亚军 ZHANG Hua;WU Baichun;ZHANG Xiaofei;LIU Yiyang;MAO Yajun(CNPC Research Institute of Safety and Environmental Technology,Beijing 102206,China;State Key Laboratory of Petroleum Pollution Control,Beijing 102206,China)

机构地区：[1]中国石油集团安全环保技术研究院有限公司,北京102206 [2]石油石化污染物控制与处理国家重点实验室,北京102206

出　　处：《环境工程学报》2023年第5期1451-1462,共12页Chinese Journal of Environmental Engineering

基　　金：中国石油研究与技术开发项目(2021DJ6604)。

摘　　要：为降低电脱盐废水污染物含量并去除顽固有机物,采用Fe和Al电极对电脱盐废水进行电絮凝预处理,采用气相色谱-质谱(GC-MS)、紫外可见光谱(UV-Vis)、三维荧光光谱(3D-EEMs)和共存离子检测等方法对电絮凝破乳分离机制进行分析,利用响应曲面方法(RSM)对电絮凝处理工艺进行优化。结果表明,电絮凝处理电脱盐废水15 min后,几乎检测不到碳数>11的有机物;反应20 min后,电脱盐废水在266 nm处紫外特征吸收值降低了55%,而电脱盐废水的2个特征荧光峰并未明显改变;反应20~25 min时,Ca^(2+)、Mg^(2+)、Cl^(-)的去除率达到最高,但Cl-浓度随后又有所升高,显示出体系中发生了氧化还原反应;采用Fe电极处理电脱盐废水时,化学需氧量(COD)去除率和总油去除率均与反应时间、电流密度符合二次回归模型,电流密度对污染物去除率的影响更为显著;电絮凝处理电脱盐废水的最优反应条件为电流密度4.2 mA·cm^(-2)、反应时间25.4 min,此时COD去除率与总油去除率的模型预测值分别为80.8%和93.5%。可以推断,电絮凝以电场破乳、絮凝、气浮、氧化等耦合作用实现了电脱盐废水的高效破乳除油。本研究结果可为电絮凝技术处理电脱盐废水的规模化应用提供参考。To lower pollutants contents and remove recalcitrant compounds from desalter wastewater,electrocoagulation with Fe and Al electrodes was employed to treat desalter wastewater.Gas chromatography-mass spectrometry(GC-MS),ultraviolet visible spectroscopy(UV-vis),three-dimensional fluorescence spectroscopy(3D-EEMs)and coexisting ion analysis were used to explore the demulsification and separation mechanism.The operating conditions of electrocoagulation were optimized using a response surface methodology(RSM).Results showed that almost no organics with carbon atom numbers greater than 11 could be detected beyond 15 min treatment.After 20 min,the characteristic absorption value of desalter wastewater at 266 nm decreased by 55%,while the two main fluorescence peaks of desalter wastewater did not change significantly.At 20~25 min,the highest removal rates of Ca^(2+),Mg^(2+)and Cl^(−)occurred,but Cl-content increased subsequently,indicating that the oxidation-reduction reactions happened in the system.As desalter wastewater was treated by electrocoagulation with iron electrodes,the removal rates of chemical oxygen demand(COD)and total oil correlated with the variables of current density and reaction time,which followed the quadratic regression model,and current density had a significant effect on the removal rates.The optimal reaction conditions for electrocoagulation were obtained as following:current density of 4.2 mA·cm^(−2)and reaction time of 25.4 min,where the predictive removal rates of COD and total oil were 80.8%and 93.5%,respectively.It can be concluded that desalter wastewater was efficiently demulsified and oil in it was removed by the coupling effects of electric field demulsification,flocculation,air floatation and oxidation.This study provides a reference for the large-scale application of electrocoagulation technology to treat desalter wastewater.

关 键 词：电脱盐废水 电絮凝 破乳 RSM优化 COD去除 总油去除 

分 类 号：X703[环境科学与工程—环境工程]