544 / 2024-07-11 15:06:12

Study on the Treatment of Shale Gas Wastewater by Persulfate Advanced Oxidation

Shale gas wastewater; Persulfate; Advanced oxidation; Chemical oxygen demand; Free radicals

Subtheme 3: Eco-hydraulics and Environment > Topic 5: Theory and Technology of Water Eco-environment Restoration

The treatment of shale gas wastewater presented significant challenges as an industrial wastewater, due to its complex composition, high salt content and low biodegradability. In this study, the alkaline activated persulfate (NaOH/PMS) advanced oxidation method was used in the treatment of shale gas wastewater. The effect of the reaction parameter and the action mechanism were investigated. The results showed that when the dosage of persulfate was 7 g/L, the initial pH value was 12, and the reaction temperature was 90 ℃, the chemical oxygen demand (COD) removal rate reached more than 80%. When coupled with ultraviolet (UV) light, the removal rate of COD reached as high as 90%. It was determined through electron paramagnetic technology and quenching experiment that there existed two kinds of free radicals, SO₄^-· and OH·, in the reaction process, while SO₄^-· plays a major role. The mechanism of COD removal by the advanced oxidation method mainly attributed to the oxidative degradation of organics by SO₄^-· and OH·. The formation of free radicals in the system could be promoted when coupled with UV light, and then the treatment efficiency enhanced. The research provided a more simple and effective technology for the treatment of shale gas fracturing flowback wastewater.