UASB-A/O工艺处理垃圾渗滤液短程生物脱氮的实现

Achieving nitrogen removal from landfill leachate via UASB-A/O process

应用缺氧/厌氧UASB-A/O组合工艺处理高氮晚期渗滤液,在获得稳定有机物和氮同步去除的前提下,考察了如何实现并维持A/O系统内稳定短程硝化的途径.结果表明：在单一UASB反应器内,同时发生了缺氧反硝化和厌氧产甲烷的反应,有机物和NOx^--N去除速率分别为5.3,1.1kg/（m^3·d）.12-30.6℃时,经过54d的运行,A/O反应器实现短程硝化（亚硝态氮积累率〉50%）,此后亚硝态氮积累率迅速上升,70d后,亚硝态氮积累率稳定在90%以上.在A/O反应器内,游离氨和游离亚硝酸协同作用是实现并维持稳定短程硝化的决定因素.此外,以pH值作为A/O硝化反应进行的过程控制参数,可准确把握硝化终点,避免过度曝气破坏短程硝化,为氨氧化菌的生长创造有利条件,有效抑制亚硝酸盐氧化菌的生长并逐渐从系统中淘洗出去,实现了硝化菌种群的优化,荧光原位杂交技术检测也证明这一点.

Treatment of real leachate from municipal landfill with high ammonia nitrogen content was investigated by using lab-scale anoxic/anaerobic UASB-A/O process. On the basis of achieving simultaneous COD and nitrogen removal, how to achieve and stabilize partial nitrification in the A/O reactor was studied. Denitrification and methanogenesis were conducted in UASB reactor, and the average removal rate of organics and NOx^--N were 5.3, 1.1 kg/（m^3·d）, respectively. Partial nitrification was achieved （nitrite accumulation ratio was above 50%） after 54 days operation, and after 70days, nitrite accumulation ratio in A/O reactor reached above 90% at ambient temperature of 12 to 30.6℃. Stable and long term partial nitrification was achieved due to the cooperative effect of free acid （FA） and free nitrous acid （FAN）. Destruction of partial nitrification caused by extended aeration was avoided by using pH as process control parameter. Nitrifying population was optimized by establishing favorable environment of AOB and inhibiting the growth of NOB, then NOB was washed out from the biological system, which was proved by fluorescence in situ hybridization （FISH）.