Selective adsorbing and air-floating treatment method and device for sewage from oilfields

The invention provides a treatment method and a treatment device for sewage from oilfields. The device consists of two parts, namely an adsorbing and mixing part and a flotation column air-floating separation part. A mixing tank or a static mixer serves as an adsorbing and mixing device and a cyclonic-static microbubble flotation column serves as an air-floating separation device. According to the requirements on process, a crusher and a ball crusher can be configured as anterior treatment devices and a pressure filter can be configured as a subsequent treatment device. A coal-base absorbent is prepared into uniform slurry with the sewage from the oilfields or purified water; the coal-base absorbent and the sewage from the oilfields are added into a stirring device together and then added into the flotation column for air-floating separation; a floating slag (an oil, water and coal base) consisting of oil content, bubbles and suspensions after being gathered and collected by a bubble collecting tank is discharged from the top of the column; and a purified effluent is discharged from the bottom of the column. The method and the device have the advantages that: the addition of any chemical auxiliary agent is avoided in the production process; sludge is not produced; and the production cost is reduced due to the fact that the coal-base absorbent after absorbing crude oil and the suspensions can directly serve as a fuel.