Wastewater that is generated from chemical industries mostly contains thiosulfate substance that is totally polluted and can cause severe pollution if not discharge with proper treatment Examples of these wastewater streams in petroleum refineries and gas processing plant include sour water, sour water stripper bottom and spent caustics. The Environmental Protection Agency (EPA) and various local agencies have placed limits on the allowable levels of these substances in industrial wastewater effluent streams.

Therefore, wastewater had to be treated first before it is being discharged or reintroduced into the receiving streams or environment. This project involves the study of the factors effecting the thiosulfate removal from the aqueous solution by using the advance oxidation technique. Hydrogen Peroxide (H₂O₂) is proposed as the oxidation agent in this study with the presence of solid Ferric Oxide (Fe₂O₃) catalyst because it can convert thiosulfate to sulfate efficiently. Besides, the use of the heterogeneous catalyst could lower the operating cost because the pollution of the treated water by the catalyst itself can be avoided.

The study concerning the factors that will affect the advance oxidation process also is proposed which are thiosulfate concentrations in the aqueous solution, hydrogen peroxide (H₂O₂) concentrations, amount of the catalyst and operating temperatures. The expected results for the research are the value of thiosulfate concentration drop and sulphate formation.

Other parameters which are temperature and pH value are also being recorded to observe their trends throughout the study. The analysis of the result will be done using UV Visible Spectrophotometer to determine the effectiveness of the study. At the end of the project, the kinetic model for the process would be developed.