Study On Treatment Of Cutting Fluid Wastewater

According to its characteristics of high emulsification stability,complicated organic components,poor biodegradability and high COD,cutting fluid wastewater has become one of most difficult waste to deal with in water treatment industry.Especially for the medium and small-sized machine processing enterprises with wide distributions and smaller scales,it's meaningful to develop an easy and high efficient treatment in practice on cutting fluid wastewater.Both processes of the coagulating demulsification-Fenton oxydation and coagulating demulsification-Fenton-like reaction catalyzed by the copper loaded iron powders on cutting fluid wastewater were studied experimentally.On the basis of the comparation of the two treated results,the optimal process has been achieved,and then the catalytic mechanism of the copper loaded iron powders in Fenton-like oxydation in cutting fluid wastewater treatment were discussed.The main results are as follows:The coagulating sedimentation method was used to pretreat the cutting fluid wastewater by demulsification,the optimal conditions of coagulation demulsification were:initial pH was 3,the dosage of Al₂?SO₄?₃·18H₂O and PAM was 10g/L and 60mg/L,respectively.After the coagulation and precipitation process,the removal efficiency of COD,Turbidity,Chroma,Oil content were 70.0%,96.2%,97.6%,93.4%,respectively.The Fenton reaction was used as an advanced treatment of the demulsified cutting fluid wastewater,the optimal conditions of Fenton reaction process were:initial pH was 3,the mole ratio of Fe²⁺and H₂O₂ was 1:90,the dosage of FeSO₄·7H₂O was 5.487g/L,reaction time was 3h,and then the pH was adjusted back to 10.After the Fenton reaction process,the removal efficiency of COD,Turbidity,Chroma,Oil content were 85.3%,79.8%,81.0%,88.6%,respectively.The Fenton-Like reaction catalyst of copper loaded iron powders was prepared by single displacement reaction,and then the catalyst was characterized by SEM,XRD and ICP.The results indicated that the some single Cu was loaded to the catalyst surface of the iron powders and the coverage ratio of Cu is 5.02%.Effects of pH,catalyst dosage,reaction time and coagulation-precipitation on the treatment efficiency were experimentally studied in the waste cutting fluid treatment via Fenton-like reaction catalyzed by copper loaded iron powder.The optimal conditions of Fenton-like reaction catalyzed by copper loaded iron powder were achieved as the initial pH of wastedwater was 3,the mole ratio of Fe²⁺and H₂O₂ was 1:80,catalyst dosage was 4.228 g/L,reaction time was 3 h.After Fenton-like reaction,the pH of the waste was adjusted to 10 and 10g/L PAC was added for coagulation and flocculation,the removal efficiency of COD,Turbidity,Chroma,Oil content were 96.7%,78.1%,83.0%,93.0%,respectively.Compared with the Fenton reaction process,the COD removal efficiency of the Fenton-like reaction process catalyzed by the copper loaded iron powders increased 11.4%,which indicted that the loading of single copper on the iron-based Fenton catalyst can improve its catalytic activity significantly.The catalytic mechanism was as follows:when the single copper exists,the Fenton-like reaction can be carried out on and on,the·OH concentration in the liquid phase can be maintained a high level,so as to solve the shortcomings of the unstable and unsustained·OH concentration in the classic Fenton oxydation reaction system.The COD concentration of the cutting fluid wastewater,supplied by Oemeta?Wuhan?Co.,Ltd.,was as high as 46000⁵0000 mg/L.After the coagulating demulsification and Fenton Oxydation treatment,the removal efficiency of COD,Turbidity,Chroma,Oil content were 95.4%,99.2%,99.5%,99.3%,repectively.However,the remain COD can still be more than 2000 mg/L.While after the treatment of coagulating demulsification and Fenton-like reaction catalyzed by copper loaded iron powder,the removal efficiency of COD,Turbidity,Chroma,Oil content were 99.0%,99.2%,99.6%,99.5%,respectively.What's more,the latter treated waste almost reached the?-class of sewage discharge standard and can be introduced into the sewage disposal systems of industrial parks.In conclusion,the optimal treatment process of cutting fluid wastewater by coagulating demulsification and Fenton-like reaction catalyzed by copper loaded iron powder is high efficiecy and can meet the requirements of cutting fluid wastewater treatments.