Oily wastewater purification method and system

The invention discloses an oily wastewater purification method and system. The purification system comprises a flocculating agent adding device, a micro-nano bubble generating device, a wastewater source, a wastewater purification zone and a pumping device for pumping oily wastewater, wherein the pumping device, the flocculating agent adding device and the micro-nano bubble generating device are respectively arranged between the wastewater source and the wastewater purification zone. The purification method provided by the invention comprises the step that a flocculating agent and micro-nano bubbles are added to the oily wastewater so that the micro-nano bubbles carry flocculated alumen ustum particles in the oily wastewater to a water surface, and sewage comprising alumen ustum on the water surface is removed. The method utilizes the advantage of enough long retention time of the micro-nano bubbles in water and can ensure that a plenty of superfine micro-nano bubbles are wrapped while alumen ustum obtained through reaction of oil components and the flocculating agent is formed, thus forming copolymers of suspended solids and bubbles; and as the specific gravity of the copolymers is far smaller than that of water, the copolymers float to the water surface, and the purification effect of the oily wastewater is ensured in the end.