Study Of Fe-C Micro Electrolysis Combined Pretreatment Process For High Density And Refractory Organic Wastewater

In order to ensure that the wastewater could meet the discharge standard,the pretreatment of high density and refractory organic wastewater become more and more important.The research of its treatment technology was always considered being a hot and difficult field.If we take direct treatment on this part of waste water,the sewage treatment system will be impacted.If we use the incineration method,the cost will be too high.In this paper,the high density and refractory reactor base solution which was from a pharmaceutical enterprise in Ningbo was pretreated by Fe-C micro-electrolysis,coagulation sedimentation and O₃ oxidation combined process.The experimental results show that this pre-treatment process can remove most of COD_Cr in wastewater and the biodegradability of wastewater can also be improved.The optimal conditions of Fe-C micro-electrolysis process as follows:the volume ratio of wastewater to iron was 3:1,the volume ratio of Fe to C was 1:1,initial pH was 5.15,reaction number was 2,each reaction time was 30mins.The concentration of COD_Cr decreased from 82573mg/L to 19355mg/L,the removal rate reached to 76.6%.The reaction of Fe-C micro-electrolysis process could accord with kinetic model of second order reaction.The optimal conditions coagulation sedimentation process as follows: initial pH was 7,dosage of PAC was 500mg/L,dosage of PAM was 8mg/L.At first,stirring 1 min under 150r/min,then stirring 5mins under 50r/min,at last,precipitating 10mins.Under the optimal conditions,the concentration of COD_Cr decreased from 19104mg/L to 5406mg/L,the removal rate reached to 71.7%.During the research of O₃ oxidation process,reaction time was tested to find their affect on O₃ oxidation process.The optimal conditions as follows:the volume of wastewater from coagulation sedimentation process was 1.8L,initial pH was 9.5,O₂ flow rate was 80L/h,reaction time was 10mins.The removal rate of COD_Cr reached to 35.6%.Under this pretreatment process,the total removal rate of COD_Cr concentration reached to 96.8%,the ratio of B/C increased from 0.1 to 0.35,the biodegradability was improved remarkably,the treatment cost is only 4.36 yuan per ton wastewater.The results show that the combined pretreatment process of high density and fefractory organic wastewater which put forward in this paper is cost-effective and technically feasible.It can solve impact load problem of conventional wastewater treatment system caused by high density and fefractory bath solution or base solution.If we treat it as hazardous solid waste,the cost will be 3000 yuan per ton wastewater.So this method can be substabtial cost savings for the enterprise.Economic benefits and environmental benefits are signiflcant.It has popularization and application of better value.