Abstract: To address the prominent issue that the desalter wastewater from atmospheric-vacuum distillation units contains high levels of H2S and combustible gases and its quality cannot stably meet standards due to oil and sludge contamination, a technical route combining atmospheric flash evaporation with high-efficiency cyclonic dissolved-air flotation CDFUintegrated with the existing gravity-settling oil-removal process effectively resolves the problems of high oil and solids content, combustible gases, and elevated hydrogen sulfide in the desalter wastewater. After retrofitting, petroleum content decreased by 73.6%, COD (Chemical Oxygen Demand) by 32.7%, and the volume concentrations of H2S, combustible gas, and VOCs dropped by 56.85%, 57.93%, and 38.25% respectively. The desalter wastewater quality improved significantly, reducing its impact on the downstream wastewater system and eliminating safety hazards.

Keywords: desalter wastewater; cyclonic dissolved-air flotation; suspended solids; flash evaporation