氨氮对内循环生物流化床亚硝化过程影响

为实现内循环生物流化床(ITFB)短程脱氮处理高氨氮废水,在小试ITFB反应器内考察了氨氮浓度对生物膜亚硝化特性的影响.通过5个月的连续试验,研究了ITFB反应器历经启动培养、短暂亚硝化、硝化系统破坏、硝化系统恢复、完全硝化五个过程中,氨氮、硝酸盐氮和亚硝酸盐氮的转化规律及游离氨毒性作用对短程硝化过程的影响.试验结果表明:反应器启动初期出现了短暂亚硝化,平均亚硝化率为79%;在进水氨氮浓度增加到300 mg/L时,系统再次实现了亚硝化,平均亚硝化率达81%,但由于游离氨浓度的影响使得系统硝化能力受到严重影响,系统氨氮去除率降低至22%;系统恢复后,亚硝化现象不明显.反应器内游离氨浓度随进水氨氮浓度升高而增加至8 mg/L时,系统内硝化细菌和亚硝化细菌活性均受到抑制.通过提高进水氨氮浓度来实现系统短程脱氮过程稳定运行的可逆性较差.

Effect of ammonia concentration on nitritation process in internal-circulation three-phase bio-fluidized bed (ITFB)

In order to achieve partial nitrification via nitrite(nitritation) in internal-circulation three-phase bio-fluidized bed (ITFB) to treat high strength nitrogen,the effect of ammonia concentration on the biofilm nitritation process was investigated in a lab-scale ITFB reactor.During five months,the experimental periods were divided into five different phases,including the startup phase,the temporary nitritation phase,the destroy phase of nitrification,the recovery phase of nitrification and the complete nitrification phase.The transformation relationship among nitrogen species and the inhibition effect of free ammonia on nitritation process were investigated.The results showed that the nitritation ratio of 79% was achieved under the start-up condition.When the ammonia concentration in influent increased from 100mg/L to 300mg/L,partial nitrification was obtained again and the average nitritation ratio was 81%.However,the nitrification capacity was destroyed by the high concentration of free ammonia;correspondingly the ammonia removal rate was decreased to 22%;no nitritation was observed after the system was recovered.The activities of AOB and NOB would be inhibited simultaneously when FA concentration increased to 8mg/L.It was not very feasible to achieve stable nitritation process by increasing ammonia concentration in the influent.