| 摘要 |
A compact dissolved-air-flotation (DAF) clarifier treats raw water with suspended solid contaminants first in a flocculator at the center of an annular tank where microscopic air bubbles float flocked contaminants to form a floating sludge layer. The flocculator has a fixed, cylindrical sidewall. A first clarification, calming and degassing occur here. The water then flows radially outwardly into the tank with a straight cylindrical outer wall where further quiet clarification occurs. A third level of clarification occurs in a lower portion of the tank, specifically, within a set of fixed, inclined lamellae, where a final clarification occurs. The bottom wall of the tank has a set of apertures which allow a gravity flow of clarified water through a layer of pressurized gas to an underlying collection compartment. A set of rotating paddles push the sludge layer up a ramp to an opening in an inclined discharge conduit. The paddles extend generally from the region over the full surface area of the tank, to its outer wall, which is preferably cylindrical. The ramp twists about its radial axis, being shallower and longer at its outer edge and steeper and shorter at its inner edge. An offset drive operating through a belt rotates the paddles, a movable cylindrical wall surrounding the lower portion of the fixed flocculator wall, and at least one scraper secured at one end to the movable wall and extending radially under the lamellae. |
