METHOD AND APPARATUS FOR FLOATATION WITH DISSOLVED AIR AND SIMILAR GAS-LIQUID CONTACTING OPERATION

摘要

PROBLEM TO BE SOLVED: To more perfectly and rapidly separate a suspended substance from a liquid medium by allowing a mixture of an untreated liquid and a liquid saturated with dissolved air under pressure to flow through a vortex passage and carrying the suspended substance to the surface of the liquid within the vortex passage while raising fine air bubbles generated from the liquid through the liquid mixture. SOLUTION: Both of an untreated liquid and a dissolved air-containing liquid are mixed by a mixer 18 and the mixed liquid flows through the passage of a flotation tank 10 and the suspended substance in the mixed liquid is removed to be discharged to a sediment trap 26 and all of residual particles are removed by a strainer 28. The treated liquid from the strainer 28 is sent to a liquid sump 30. A small amt. of the treated liquid saturated with dissolved air under pressure is recirculated to the inlet 20 of the tank 10 as a liquid. Compressed air is introduced into the liquid from a supply source 44 by a pump 46 and the dissolved air in the liquid is accumulated in a dissolved air separation tank 48 to be let escape by a relief device 47. The suspended substance or scum floated to the surface of the liquid in the tank 10 is removed through an overflow trough 34.