Research on the treatment of sludge drying gas spray wastewater using discharge free radicals

Wastewater from the spray absorption treatment of sludge drying gas is a kind of refractory wastewater with poor biodegradability. In this study, the free radicals generated from the double dielectric barrier were  innovatively used for the degradation of simulated spray wastewater. The effects of residence time, input power, initial pH, aeration rate, and discharge area on the degradation rate and COD (chemical oxygen demand) removal rate were investigated. The optimal conditions were as follows: residence time=120 min, input power=170.0 W, initial pH=5.54, aeration rate=0.9 mL/min, discharge area=10.8 cm², and the initial concentrations of NH₃, H₂S, methanethiol, trimethylamine, benzene and toluene were 250, 250, 50, 50, 50 and 100 mg/L, respectively. Meanwhile, it was also found that hydroxyl radical \(\left( { \cdot {\text{OH}}} \right)\) played an important role in the degradation process.