in filter device 18 is removed from the latter via a conduit 21 can be also eventually recycled into the whole plant or installation if the utilization of surplus water from conduits 19 and 21 as a usable or custom water is impossible this water is expelled as exhaust water however such an exhaust water is significantly settled due to the method according to the invention the efficiency of the inventive method is illustrated by the following example the concentrated slime containing water for processing row gas is originated from a plant for a gasification of coal operated according to koppers totzek process the slime containing water discharged from settling tank 2 through conduit 6 has the following composition ______________________________________ ph 8 0 solids g l 205 nh sub 4 sup mg l 134 s sup 34 0 7 so sub 3 sup 34 1 4 s sub 2 o sub 3 sup 34 3 6 so sub 4 sup 34 746 cn sup 34 8 6 scn sup 34 6 9______________________________________ the amount 15 m spsp 3 h of the concentrated slime containing water at the temperature of about 40 u00b0 c is fed into the first oxidation reactor 7 of the first oxidation stage this first reactor 7 has a clear diameter of 1 20 m and the height of 3 50 m.