Ultrasound Activate Hydrogen Peroxide And Persulfate In The Treatment Of Landfill Leachate

With the growth of population and the development of society,the quantity and complexity of waste are increasing..As a kind of high-concentration refractory organic wastewater,landfill leachate is inevitable in waste disposal,without proper disposal,the leachate will cause great harm to the environment.At present,landfill leachate,especially mature leachate,has very low biodegradability.The traditional biochemical process is difficult to meet the requirements.It is imminent to develop efficient,green,and economic technology to the landfill leachate's treatment.In this paper,we use ultrasound activate hydrogen peroxide and persulfate oxidation of mature landfill leachate,inspecting the impact factors of ultrasonic-based advanced oxidation processes in landfill leachate treatment,and exploring the challenges faced by this method in practical applications.Firstly,this paper use single ultrasound to treat landfill leachate,the time is 4h,adopting COD_Cr,UV₂₅₄,color and ammonia nitrogen as indicators,investigate the influence of temperature,ultrasonic power and pH.The results showed that ultrasonic power and pH have no significant effect on the ultrasonic treatment of leachate alone under the conditions of this article,and the increase in temperature can promote the reaction.From the UV absorption spectrum,single ultrasonic can effectively change the components of leachate,but its oxidation effect is not obvious,single ultrasound is not suitable to leachate oxidation.Then,treat the leachate by US/H₂O₂ system,adopting COD_Cr,UV₂₅₄,color,and ammonia nitrogen as indicators,the influence of temperature,H₂O₂ dosage,and pH was investigated.The results showed that the effect of temperature with H₂O₂ alone was not significant,but it had a significant effect under US/H₂O₂.Though high temperature can accelerate the oxidation,it can also promote the decomposition of H₂O₂,resulting in a significant reduction of H₂O₂that can be used for oxidation,and thus in a long reaction time,the higher the temperature,the smaller the removal of UV₂₅₄,COD_Cr,and color.In the US/H₂O₂ system,ammonia nitrogen reducted rapidly at high temperatures,the higher the temperature,the higher the removal rate of ammonia nitrogen.In the US/H₂O₂ system,high pH is more conducive to the removal of UV₂₅₄,NH₃-N,color,and COD_Cr,and increasing the H₂O₂ dosage can effectively improve the system's removal efficiency of each index.From the UV absorption spectrum,ultrasound can promote the oxidation of H₂O₂ in the leachate,but the effect is not outstanding.Finally,treat the leachate by US/PS system,adopting COD_Cr,UV₂₅₄,color,and ammonia nitrogen as indicators,the influence of temperature,PS dosage,and pH was investigated.The results show that though ultrasound does not activate persulfate effectively at lower temperatures,it has a significant effect on persulfate activation at high temperatures.Temperature has no significant effect on the removal of ammonia nitrogen in the US/PS system,and US/PS system does not perform well for ammonia removal.US/PS system showed better organic degradation under acidic conditions,while alkaline conditions favored the removal of ammonia nitrogen.Na₂S₂O₈ remained after terminate the reaction,and the removal rate of each index increased with the increase of persulfate dosage.Through the comparison of the above systems,we can find that the US/H₂O₂ peroxide system and theUS/PS system have their advantages in different pollutant indicators.