Patent ID: 8211290

Claim:
A method for removing impurities from waste water by electroflotation, the method comprising the steps of: passing the waste water to be cleaned through an electrolytic cell ( 28 ) provided with two metal electrodes ( 1 , 2 ) of different electronegativities; performing electrolysis between the two electrodes ( 1 , 2 ), such that the more electronegative electrode ( 1 ), which is non-wearing in a cleaning process, is used for producing hydrogen gas and hydroxyl ions from water, and that the less electronegative electrode ( 2 ), which is an active, wearing electrode in a cleaning process, is used for producing metal ions in a solution to be cleaned, the method further comprising a combination of following steps: automatically controlling the cell current to obtain a controlled electric field in the cell; effecting in the cell in the controlled electric field a desired oxidation reduction reaction for removing one or more designated impurities from water to be cleaned; feeding the mass flow from the cell to a separation tower ( 30 ) that separates a floc and purified water and allowing the hydrogen gas to raise the floc in the separation tower ( 20 ); using coaxial pipes as electrodes, the coaxial pipes defining an uninterrupted, generally cylindrical electrolysis space in the cell through which the hydrogen gas raises the floc along a generally linear path that is not interrupted by structural elements that cause mixing in the cell so the hydrogen gas raises the floc through the electrolysis space without mixing the floc with the purified water so as to allow the formation of the floc, the inner electrode pipe being the more electronegative electrode ( 1 ), having holes; and feeding flush water intermittently, during wash cycles, through the inner electrode pipe by pressure for producing flush water sprays through the holes against inner surface of the outer electrode pipe.