Aerobic Contact Oxidation + Fenton Process For Treatment Of Tannery Wastewater

The tannery wastewater is a kind of typical industrial wastewater which contains high COD, high nitrogen, high suspended substance. If discharged without proper treatment, it could seriously pollute the aquatic environment. The removal of COD and ammonia nitrogen is the key of the industrial tannery wastewater treatment. O n the premise of low removal rates of COD and ammonia nitrogen in the process of tannery treatment, the biological contact oxidation is used to process tannery wastewater, and to research the operation condition which can realize the best treatment effect. In the presence of biochemical effluent COD is high, this experiment adopts the Fenton oxidation technology to process biochemical effluent as advanced treatment, and to explore the operation condition of making the final effluent COD standard.After the success of biofilm in the inoculated biological contact oxidation reactor, the influence of these factors, such as anoxic denitrification HRT, aerobic nitrification HRT, mixed liquor recycle, DO, influent loading of NH3-N on denitrification were investigated on the premise o f the efficient removal of organic matter. Ultimately optimum condition parameters of A/O biological contact oxidation process to tannery wastewater were established. It was showed that when the influent COD, ammonia-nitrogen and TN were 550~986,84~127,99~148 mg/L, respectively, and if the anoxic part and mixed liquor recycle were removed, the aerobic HRT was maintained at 18 h and DO in the aerobic zone was controlled at 2.5~3.5 mg/L, simultaneous nitrification and denitrification occurred in the aerobic zone and the average removal rates of COD,ammonia-nitrogen and TN were 74.76%, 98.35% and67.63%, respectively. The biochemical effluent ammonia- nitrogen met the first class discharge standard of second period level of Water Pollution Discharge Limits of Guangdong Province(DB44/26-2001):NH3-N≦10 mg/L.The Fenton oxidation technology is used as advanced treatment to process the biochemical effluent COD. When theCODOH/mm22 was 1.5, CODFe/mm2(10)was 0.2, p H was 3 and reaction time was 4 h, COD could be reduced from 150~220 mg/L to less than 100mg/L.Through the above study to determine the operation condition which can realize the best removal rates of COD and ammonia nitrogen of the A/O biological contact oxidation + Fenton combination process for tannery wastewater.