Oxidation process for improving the environmental quality of water containing sulfur and/or inorganic sub-six-sulfur-containing impurities

Claim 1

In the method of improving a water stream containing inorganic sub-six-sulfur-containing impurities by oxidizing said sulfur to sulfate using a gas comprising molecular oxygen, the improvement which comprises using as feed a stream containing said impurity in an amount, calculated as sulfur and per million parts (weight) of water, in the range from about 100 to 20,000 parts (weight), and said impurity being at least one of the group consisting of elemental sulfur and inorganic compounds consisting of sub-six sulfur plus at least one element of the group consisting of oxygen, hydrogen, and carbon, and water-soluble salts of acids included in said compounds, and oxidizing said sub-six sulfur to sulfate by contacting said stream with molecular oxygen for a period in the range from about 0.1 to 5 hours and sufficient for at least a 90 percent conversion of said sub-six sulfur to sulfate, said oxidation being effected by carrying out the contacting in the presence of at least enough strong base to provide at least one equivalent of hydroxyl ion per gram atom of sub-six sulfur in said impurity, said contacting being effected in the substantial absence of heavy metal sub-six sulfur oxidation catalysts and said oxidation being effected by maintaining the stream in the liquid phase: a. at a standard pH of at least about 9.6; b. at a temperature in the range of from about 90° to 180°C; and c. at a partial pressure of molecular oxygen gas of at least about 0.5 atmosphere.