Chemistry of inorganic compounds – Sulfur or compound thereof – Binary compound
Reexamination Certificate
2005-08-09
2005-08-09
Hruskoci, Peter A. (Department: 1724)
Chemistry of inorganic compounds
Sulfur or compound thereof
Binary compound
C210S716000, C252S175000, C252S178000
Reexamination Certificate
active
06926878
ABSTRACT:
Arsenic and TOC are removed from drinking water or wastewaters by use of finely-divided metallic iron in the presence of powered elemental sulfur or other sulfur compounds such as manganese sulfide, followed by an oxidation step. A premix may be produced for this process, by adding the iron, sulfur and oxidizing agent to water in a predetermined pH range. The iron and sulfur are mixed for a period of time dependent upon the temperature and pH of the water and the presence of complexing or sequestering minerals and organic acids in the water. An oxidizing agent is added to the mixture and agitating is continued. In a preferred embodiment the oxidizing agent is hydrogen peroxide. Water is decanted from the mixture after a sufficient reaction time, to produce a concentrated premix. This premix can be added to water intended for drinking or to industrial effluents containing toxic materials. Use of various gradations and mixtures of this sulfur-modified iron (SMI) premix have been successfully demonstrated to remove the following toxic substances from water: arsenic (arsenite and arsenate); disinfection byproducts and precursors; copper; chrome VI; sulfate; and chlorinated solvents including trichloroethene. Metals removed may be present in the untreated water in either the dissolved state or as a fine particulate. SMI has been fabricated using sulfur in the amount of up to 50% of the weight of the iron. SMI premix has been manufactured using a wetted but non-fluid mix at room temperature and at elevated temperature. SMI has been successfully demonstrated in pressure and gravity contact beds in both upflow and downflow modes. It has been prepared in uniformly-graded media similar in size and gradation to commercially-available filter media. Spent SMI can be recycled as a non-hazardous material as feed material to a steel production facility.
REFERENCES:
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patent: 5575919 (1996-11-01), Santina
patent: 5866014 (1999-02-01), Santina
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Freiburger Thomas M.
Hruskoci Peter A.
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