Table-top numbering-up 3D-printed miniaturized hydrocyclone for high-efficiency and high-throughput separation of oil-in-water emulsions

Abstract

Oily wastewater from home and industrial effluents, as well as marine oil spills, poses significant environmental problems, such as water and soil contamination and ecosystem devastation. We here developed a parallelized miniaturized hydrocyclone (mHC) system consisting of multiple mHCs and a flow distributor for high-efficiency and high-throughput separation of oil-in-water emulsions. From a manufacturing perspective, our system can be easily and rapidly created using 3D printing technology. It was also specifically designed to provide simple and durable connections between tubes and components, eliminating the need for a time-consuming bonding process. Direct visualization of primary and secondary vortex flows generated within the mHC device was achieved, allowing the variation of the vortex flows as a function of the feed flow rates to be analyzed. Furthermore, we demonstrated that a single mHC was capable of separating six types of oil-in-water emulsions with different oil phases and a separation efficiency greater than 90 %, with olive oil-based emulsions achieving a remarkable separation efficiency of 98.3 % at the optimal feed rate of 200 mL/min. By numbering-up a single mHC and incorporating a 3D-printed flow distributor to ensure a uniform flow distribution into each individual mHC, we can construct a parallelized mHC system. The separation system can process an estimated 3,168 L (837 US gallons) of mineral oil-based emulsion per day with a separation efficiency of approximately 97 %. The results of this study can be further enhanced by modifying the flow distributor, increasing the number of single mHCs, and introducing high-performance pumps.