Study On The Degradation Of Organic Matter And Its Mechanism In Metalworking Fluids By UV/Fenton And UV/Persulfate

Because of its complex and diverse,difficult biodegradable,the metalworking fluids wastewater,became a very difficult category in the environmental field.The Fenton technology has been used in the actual treatment of this kind of wastewater in recent years,but the process is complicated,and it is easy to cause a lot of waste,which will increase the difficulty in actual operation and the economic cost.While the persulfate oxidation process is easier to operate,which does not cause secondary pollution,and also has a strong oxidative and other advantages,thus people gradually applied it to the wastewater treatment research,but less in dealing with the actual metalworking fluids with Oil research.In this paper,the actual metalcutting waste liquid produced by an automobile factory in Xi'an was taken as the treatment object,and ultraviolet light was introduced into the advanced oxidation system under normal temperature and pressure to study the influence of the change of each influencing parameter on the treatment of the waste water and discuss the mechanism.Draw the following conclusions:?1?The UV/persulfate system was directly used to treat this kind of wastewater after dilution.The results showed that the combined treatment of UV+heating+persulfate?UV+?+PS?had the best effect on the wastewater treatment.The initial pH of the solution was only in the early stage of the oxidation process,the effect of treatment was obviously affected.The existence of some organic compounds in the waste water weakened the degradation of the oxidation system to a great extent ability.Therefore,considering from the characteristics of waste water,and better studying the effect of the oxidation system on the treatment of wastewater,it's first to demulsification pretreatment.?2?The best coagulation method of PAC+PAM in chemical demulsification method is found.When the pH value is about 9,the optimum dosage of PAC and PAM is 50 g/L,the highest COD removal rate was 72.05%.The turbidity of the supernatant was obviously decreased,but the color was yellowish and the flocculation was much more.On the basis of this,the UV/persulfate method was applied to the effluent water after demulsification pretreatment.?3?The removal rate of COD was about 90.12%under the conditions of S₂O₈^2-:12COD₀=0.5,adjusting pH about 7,stirring speed 80 r/min,experiment temperature 30±1?,UV irradiation time 240min,COD value was about 987.6 mg/L,the effluent was good.The UV-Vis spectra shows that the UV/persulfate system can effectively remove the chromogenic groups and non-conjugated organic compounds in the wastewater.?4?The introduction of UV light in Fenton significantly enhanced the degradation of waste liquid.The significant factors of UV/Fenton reaction were:H₂O₂ dosage>pH>Fe²⁺dosage>reaction time;The best reaction conditions were:pH=4,H₂O₂ dosage=191.30m L/L,Fe²⁺dosage=31.24 mmol/L,total reaction time=210min.,The effluent water quality is good,COD removal rate is 90.89%,COD value was about 910.6 mg/L.Overall,the UV/persulfate system is feasible and more competitive in terms of economy and practicability.