Patent ID: 7320759

Claim:
A sludge treatment method, comprising the steps of: foaming a sludge-containing liquid by blowing an ozone-containing gas into the sludge-containing liquid to generate sludge-adsorbed bubbles and discharge the bubbles from a bubble discharge port provided in an upper portion of an ozone treatment vessel, wherein the ozone-containing gas is blown into the sludge-containing liquid during the foaming step using a diffuser pipe provided at the bottom of the ozone treatment vessel, and wherein the foaming step further includes mixing the sludge-containing liquid and the bubbles using a bubble mixing blade provided at an upper portion of the ozone treatment vessel and a liquid mixing blade provided at a lower portion of the ozone treatment vessel; eluting phosphorus in the sludge-containing liquid by supplying the bubbles to a phosphorous elution vessel from the bubble discharge port thereby bringing sludge adsorbed on the bubbles and a sludge-dissolving agent into contact with each other within the phosphorous elution vessel; and decomposing waste ozone gas not dissolved in the sludge-containing liquid into oxygen, wherein the waste ozone gas is received from an upper portion of the phosphorous elution vessel.