State Key Laboratory of Heavy Oil Processing, Beijing Key Laboratory of Oil and Gas Pollution Control, China University of Petroleum-Beijing, Beijing 102249, China.
Department of Civil and Environmental Engineering, University of Alberta, Edmonton, Alberta T6G 1H9, Canada.
Chemosphere. 2021 Feb;264(Pt 2):128531. doi: 10.1016/j.chemosphere.2020.128531. Epub 2020 Oct 5.
Highly polluted crude oil electric desalting wastewaters (EDWs) severely affect the efficiency of refinery wastewater treatment plants (WWTPs). Coagulation is an efficient pretreatment to reduce the impacts of EDWs. In the present study, the influences of coagulation pretreatment on the characteristics of EDWs of three typical Chinese crude oils, Liaohe heavy oil (LHO), Karamay heavy oil (KHO) and Daqing light oil (DLO), were investigated. The stability of three raw EDWs was broken and the contents of organic pollutants were significantly reduced by aluminum sulfate coagulation. More soluble COD and polar oils were removed from LHO-EDW (1241 and 98 mg L) and KHO-EDW (779 and 57 mg L) compared to DLO-EDW (417 and 11 mg L). Coagulation significantly changed the compositions of the organic pollutants of two heavy oil EDWs; however, slightly influenced DLO-EDW, particularly the polar organic pollutants. Most types of aromatic compounds, aliphatic acids and O polar compounds were removed from two heavy oil EDWs, but mainly alkanes were removed from DLO-EDW. As such, the differences in the types of dominant polar compounds became insignificant among treated heavy oil and light oil EDWs. Coagulation notably decreased the acute biotoxicity and improved the biodegradability of all treated EDWs. The residual organic nitrogen compounds in treated KHO-EDW contributed to a higher residual biotoxicity compared to treated LHO-EDW. The results demonstrate that coagulation can effectively improve the qualities of heavy oil EDWs by lowering the contents of organic pollutants and removing recalcitrant compounds, thus guaranteeing the efficiency of refinery WWTPs.
高污染原油电脱盐废水（EDW）严重影响炼油厂废水处理厂（WWTP）的效率。混凝是一种有效的预处理方法，可以降低 EDW 的影响。本研究考察了混凝预处理对三种典型中国原油（辽河稠油（LHO）、克拉玛依稠油（KHO）和大庆轻油（DLO））EDW 特性的影响。通过硫酸铝混凝，三种原 EDW 的稳定性被破坏，有机污染物的含量显著降低。与 DLO-EDW（417 和 11mg/L）相比，LHO-EDW（1241 和 98mg/L）和 KHO-EDW（779 和 57mg/L）中更多的可溶 COD 和极性油被去除。混凝显著改变了两种重油 EDW 中有机污染物的组成；然而，对 DLO-EDW 的影响较小，特别是对极性有机污染物。两种重油 EDW 中的大多数类型的芳香族化合物、脂肪族酸和 O 极性化合物被去除，但 DLO-EDW 中主要去除的是烷烃。因此，处理后的重油和轻油 EDW 中主要极性化合物的类型差异变得不明显。混凝显著降低了所有处理后的 EDW 的急性生物毒性并提高了其可生物降解性。与处理后的 LHO-EDW 相比，处理后的 KHO-EDW 中残留的有机氮化合物导致更高的残留生物毒性。结果表明，混凝可以通过降低有机污染物含量和去除难生物降解化合物有效改善重油 EDW 的质量，从而保证炼油 WWTP 的效率。
