硝化液回流比对A^2/O-BCO工艺反硝化除磷特性的影响

Effect of nitrate recycling ratio on denitrifying phosphorus removal characteristics in A^2O-BCO process

以低C/N城市生活污水为处理对象,重点考察了硝化液回流比对A2/O-BCO(生物接触氧化)工艺脱氮除磷特性的影响.在A2/O反应池水力停留时间(HRT)为8h,污泥回流比为100%条件下,将硝化液回流比分别设定为100%、200%、300%和400%进行试验.结果表明,系统在A2/O中实现了反硝化除磷,具有很好的同步氮磷的去除效果,出水COD浓度均在50mg/L以下.上述不同硝化液回流比下总氮(TN)去除率分别为48.8%、66.5%、75.6%和62.5%,总磷(TP)去除率分别为86.0%、90.3%、91.0%和95.0%.在硝化液回流比为300%时,系统平均出水TN和TP浓度分别为14.96mg/L和0.49mg/L.系统反硝化除磷量随着硝化液回流比的增大略有增加,在硝化液回流比为400%时,反硝化除磷量高达磷总去除量的98%.

The characteristics of biological nitrogen（N） and phosphorus（P） removal under different nitrate recycling ratios were investigated in a Anaerobic/Anoxic/Oxic（A^2O）-Biological Contact Oxidation（BCO） system when treating low C/N in municipal wastewater. The results indicated that the removal of N and P was achieved simultaneously, and denitrifying phosphorus removal（DPR） process was realized with the total hydraulic retention time（HRT） of A^2O at 8h, sludge reflux ratio of 100%, and nitrate recycling ratios set as 100%, 200%, 300% and 400% respectively. The effluent concentration of COD was less than 50mg/L. The removal efficiencies of total nitrogen（TN） were 48.8%, 66.5%, 75.6% and 62.5%, and the removal efficiencies of total phosphorus（TP） were 86.0%, 90.3%, 91.0% and 95.0% under various nitrate recycling ratios. When the nitrate recycling ratio was set at 300%, average concentration of TN and TP in effluent were 14.96mg/L and 0.49mg/L. The amount of denitrifying phosphorus removed was increased slightly as the nitrate recycling ratio improved. When the nitrate recycling ratio was set at 400%, the amount of P removed by DPR accounted for 98% of the total phosphorus removed.