A method of treating wastewater resulting from hydrocarbon production operations is provided, for repurposing as a disinfectant. The method includes a) providing wastewater resulting from hydrocarbon production operations containing greater than 3 ppm bromide ion; and b) adding a sufficient amount of an oxidizing agent to convert the bromide ion to hypobromous acid used in the formation of a disinfectant solution. At least one of chloramine, bromamine, and hypobromous acid is present in the disinfectant solution to provide disinfecting properties. A source of ammonia may also be added to the wastewater, and the disinfectant solution may be blended with other water to provide blended water for use as a fracturing fluid.