Study of a novel micro-cyclonic air flotation device for enhanced oil removal from wastewater

Abstract

As global oilfields advance into mid-to-late development stages, the produced fluids contain increasingly high water content, leading to substantial wastewater volumes. Existing oily wastewater treatment systems face challenges in meeting stricter discharge standards. To address this issue, this work proposes a micro-cyclonic air flotation separator that integrates cyclonic and flotation technologies to enhance oil removal efficiency. An experimental setup was designed to systematically investigate the effects of structural and operational parameters on bubble formation and oil removal in a DN100 single-tube micro-cyclonic flotation device. Key operational parameters were selected, and structural parameters were optimized to support the development of a compact, high-efficiency separator for oily wastewater treatment. The experimental results revealed that increasing dissolved air pressure reduces mean bubble size, increases bubble number density, and raises gas holdup. Conversely, as air flow rate increases, the mean bubble size grows, the number density initially rises before decreasing, and gas holdup follows a similar trend. Optimal structural parameters were determined, under which the device demonstrated excellent oil removal performance across an oil concentration range of 200–1000 mg/L, achieving a maximum removal efficiency of 85.69%.