Pretreatment Of High Concentration Organic Wastewater Byadvanced Oxidation Combined Processes

Chemical, pharmaceutical, electroplating and other enterprises produce a lot of high concentration organic wastewater, such as waste bath, waste solvents . They are characteristic of high CODCr, low B/C, complicated components, toxic and deleterious. According to the requirements of environmental protection department, the wastewater should be treated with incineration method by professional department, but the process costs too much. In order to save the cost many enterprises discharged the wastewater after diluted ,which would bring excess emissions or pollution accidents. So how to treat the high concentration organic wastewater has been a difficult environmental puzzle.According to the characteristics of the high concentration organic wastewater , we designed advanced oxidation combined processes: ferric-carbon micro electrolysis/ultrasonic-Fenton reagent- flocculation. This pretreatment processes can debase concentration, reduce toxicity, improve B/C, change hazardous wastewater into ordinary wastewater which can be drainaged standard after conventional treatment. The optimal conditions of the Micro-electrolysis/ultrasonic process were:pH was 4.4, the volume ratio of solid to liquid was 1:4, the volume ratio of iron to carbon was 2:1, reaction number was 2, each reaction time was 60 min , aerate, the frequency of ultrasonic was 45 KHz. The optimal conditions of Fenton reagent process were: pH was 4,the volume ratio of H₂O₂ to wastewater was 4%,reaction time was 60min. The coagulation sedimentation process optimal conditions were: pH was 7, dosage of PAC and PAM were 500mg/L and 5mg/L respectively.The total removal rate of CODCr, TOC and p-nitrophenol reached 89.8%, 79.7% and 85.2% respectively when the combined processes pretreated simulation wastewater . The value of B/C increased from 0.052 to 0.346. The combined processes pretreated two kinds of practical wastewater , CODCr decreased from 163000 mg/L,15000 mg/L to 48100,1000 mg/L respectively, the removal rate reached to 70.5% and 93.3% . Ultraviolet spectrum had showed that a part of refractory materials are effectively degraded into small molecules.The advanced oxidation combined processes pretreating high concentration organic wastewater cost only 10% of incineration method. They are economic,effective and feasible in technology, So the combined processes have good application value.