A device for purification of contaminated liquid includes (a) a prepurification tank in which raw water to be purified and foaming reagent are introduced and mixed and the pH value is adjusted, whereby prepurified water is obtained; (b) at least one tower-shaped main purification block, wherein each of the at least one tower-shaped main purification blocks, includes, arranged vertically one under another; (i) a drum station for combined gas and water scrubbing by foaming; (ii) a defoaming station; (iii) an ionization station; and (iv) a collecting tank for collecting resultant purified water; (c) a separating device in which sludge from the purification tanks is introduced; and (d) at least one afterpurification filtering device connected to the collecting tank of the main purification block by a supply line and wherein a pure water outlet line extends from the at least one afterpurification filtering device.