硝化负荷对A^2O-BAF中试系统性能的影响

Effect of Nitrification Loading on Nutrient Removal Performance of Pilot-scale A^2O-BAF System

该文建立了一套中试规模"厌氧/缺氧/短时好氧(A2O)-曝气生物滤池(BAF)工艺",日处理量19.2 m3/d,考察了BAF池硝化负荷对系统处理性能的影响。该工艺由A2O池、中沉池和BAF池三部分构成,其中,A2O段HRT为4.0 h,厌氧/缺氧/好氧体积比为1∶2∶1;BAF池最初只有1座,后来改为2座,硝化负荷从0.8 kg NH4+-N/(m3·d)降至0.4 kg NH4+-N/(m3·d),硝化液回流比100%。结果表明,随着硝化负荷的降低,系统去除效果明显改善,氨氮和总氮去除率分别从66.2%和51.7%提高到88.0%和69.9%,SS去除率也从55.6%升至82.3%;COD去除效果保持稳定,平均去除率82.5%。可见,BAF容积负荷是影响A2O-BAF工艺处理性能的关键参数,将硝化负荷控制在0.4 kg NH4+-N/(m3·d)可保证系统出水达到《城镇污水处理厂污染物排放标准》一级A标准。

A pilot-scale anaerobic/anoxic/short time aerobic （A2O）-biological aerated filter （BAF） combined process was set up with treating capacity of 19.2 m3/d and the effect of nitrification loading on nutrient removal performance was investigated. This system was consisted of an A20 basin, a settler and one or two BAFs. The HRT of the A2O reactor was only 4 h with the anaerobic/anoxic/aerobic volume ratio of 1/2/1. During the operation of the process, the number of BAF was increased from one to two, and the nitrification loading was decreased from 0.8 kg NI-L＋-N/（m3 ·d） to 0.4 kg NH4＊--N/（m3·d） accordingly. The nitrification recirculation ratio was kept at 100%. The results showed that, removal performance of the system was improved greatly after the nitrification loading was decreased. The removal efficiencies of ammonia nitrogen and total nitrogen were increased from 66.2% and 51.7% to 88.0% and 69.9% respectively; meanwhile, the removal efficiency of SS was increased from 55.6% to 82.3%. The removal performance of COD was relatively stable, with average removal efficiency of 82.5%. It can be seen that volume loading of BAF is an important operation parameter influencing the performance of the A2O-BAF process. And the effluent could meet the Grade A of Integrated Wastewater Discharge Standard, GB18918-2002 when the nitrification loading of BAF was controlled at 0.4 kg NH4＋-N/（m3·d）.