Influence of non-thermal plasma pretreatment on viscous crude oil wastewater evaporation process and on quality of the distilled water

To recycle viscous crude oil wastewater through evaporation to supply feeding water for steam injection boiler is a promising technology to benefit viscous crude oil extraction. In order to improve quality of distilled water and avoid scale formation during the evaporation process, the technology of non-thermal plasma (NTP) was tried in this research to pre-treat viscous crude oil wastewater before evaporation. Firstly the wastewater was sprayed into NTP reactor tube and then sent to the evaporator. It was found that after pretreatment, the contents of SiO₂ and hardness of pretreated wastewater were reduced. Accordingly, distilled water from evaporating the pretreated wastewater was corresponded to lower hardness and decreased conductivity. The SiO₂ contents in distilled water were changed without obvious rules. However as comparing the quality of distilled water from the pretreated wastewater with that from common evaporation facilities, it can be found that the quality of distilled water from NTP treated samples was better except that its hardness is higher which was caused by foam carrying for foam remover was not available in the experimental evaporation system. Low-temperature plasma, as a pretreatment technology, also hindered hard scale formation on the heating surface of evaporator and it is possible to replace scale formation chemicals in operation, providing an economical and energy-saving way for recovering wastewater water.