Process for the catalytic treatment of wastewater

A process for continuously treating an aqueous waste stream contaminated with volatile chemically oxidizable pollutants and nonvolatile pollutants comprising, in combination, the steps of:

• (a) continuously concentrating the nonvolatile pollutants in the aqueous waste stream to be treated by a continuous evaporation process that simultaneously produces concentrated nonvolatile pollutants originally present in the waste stream and a water rich vapor phase stream substantially free of dissolved solids, the waste stream to be treated comprising inorganic nonvolatile pollutants, the water rich vapor phase stream comprising steam and at least 45% of the volatile chemically oxidizable pollutants originally contained in the waste stream;
• (b) operating the continuous evaporation process at conditions sufficient to achieve a solids content of the concentrated nonvolatile pollutants of from about 20 to about 70 wt. %;
• (c) removing from the continuous evaporation process a portion of the concentrated nonvolatile pollutants of step (b) in order to maintain the solids content of concentrated nonvolatile pollutants at about 20 to about 70 wt. %;
• (d) contacting substantially all of the water rich vapor phase stream with a solid oxidation catalyst in the presence of steam at gas phase oxidation conditions to convert the volatile chemically oxidizable pollutants, thereby producing a gaseous reaction product comprising steam and incondensible gases, the solid oxidation catalyst comprising an inorganic oxide support containing at least one metal oxide;
• (e) mixing a part of the portion of concentrated nonvolatile pollutants removed from the continuous evaporation process in step (c) with a stabilizing agent selected from the group consisting of cements, lime, fly ash, kiln dusts, alkali metal silicates, asphalts, pozzolans, and mixtures thereof;
• (f) recycling a second part of the portion of concentrated nonvolatile pollutants removed in step (c) back to the continuous evaporation process;
• and
• (g) solidifying the resultant mixture of step (e) to form a solid.

A process for treating wastewater contaminated with volatile chemically oxidizable pollutants and nonvolatile pollutants comprising, in combination, the steps of:

• (a) continuously concentrating the wastewater to be treated by evaporation to produce a first stream comprising concentrated nonvolatile pollutants and a second water rich vapor phase stream substantially free of dissolved solids, the second stream comprising steam and at least 45% of the volatile chemically oxidizable pollutants originally contained in the wastewater;
• (b) contacting substantially all of the second stream with a solid oxidation catalyst in the presence of steam at gas phase oxidation conditions to convert the volatile chemically oxidizable pollutants, thereby producing a gaseous reaction product comprising steam and incondensible gases, the solid oxidation catalyst comprising an inorganic oxide support containing at least one metal oxide;
• (c) recycling a first portion of the first stream back to the evaporation process of step (a) in order to maintain the solids content of concentrated nonvolatile pollutants at about 20 to about 70 wt. %;
• (d) heating a second portion of the first stream by direct fired heating to vaporize pollutants not volatilized by the evaporation of step (a);
• and
• (e) mixing the vaporized pollutants with the second stream prior to contact with the catalyst.