Methods of processing a fluid recovered from an oil or gas extraction operation for reuse in a hydraulic fracturing fluid are described. The methods include providing an amount of a produced fluid composition containing iron and suspended solids and controlling at least one of the conductivity, iron content, oxidative strength, and pH of the composition, such that Fenton's reagent is formed in situ. Also described are hydraulic fracturing fluids produced using fluid recovered from an oil or gas production process and treated in accordance with the methods described herein as well as systems for preparing a hydraulic fracturing fluid having, as a fluid source, fluid recovered from an oil or gas production process that has been treated in accordance with the methods described herein.