污泥对高质量浓度NO_(2)^(−)-N交叉因素的自我调控机制

Self-regulating mechanism of sludge on cross-factors of high mass concentration NO_(2)^(−)-N denitrification

高质量浓度的亚硝酸盐氮(NO_(2)^(−)-N,>100 mg·L^(−1))在反硝化过程中会抑制甚至杀死微生物,会影响工业废水脱氮效果,导致出水总氮超标。本研究为了探明高质量浓度NO_(2)^(−)-N对污泥影响,使用批次实验处理不同pH(6.5~9.5),不同初始NO_(2)−-N质量浓度(10~400 mg·L^(−1))的废水,并考察了受影响污泥的恢复能力。结果表明,游离亚硝酸盐(free nitrite,FNA)是反硝化主要的抑制因素,FNA质量浓度大于0.03 mg·L^(−1)时会对污泥正常反硝化产生短期不可逆影响,且是浓度和时间两方面共同作用的结果;当FNA低于0.01 mg·L^(−1)时,高NO_(2)^(−)-N质量浓度本身也会对脱氮造成抑制,但可通过洗泥逆转,甚至仅通过污泥自身驯化作用也可逆转抑制现象。反硝化过程中,微生物具有在一定范围内自发调节环境pH的能力;反硝化过程中体系碱度变化受碳酸盐缓冲体系影响,pH越高,水体缓冲性越好。

High mass concentration of nitrite nitrogen(NO_(2)^(−)-N,>100 mg·L^(−1))will inhibit or even kill microorganisms in the denitrification process,which will affect the denitrification effect of industrial wastewater,resulting in excessive total nitrogen in the effluent.In order to study the effect of high concentration of NO_(2)^(−)-N on sludge,track the recovery ability of the affected sludge,batch experiments were used to treat wastewater with different pH(6.5~9.5)and different NO_(2)^(−)-N mass concentration(10~400 mg·L^(−1)).The results showed that free nitrite(FNA)was the main inhibitory factor of denitrification.When the concentration of FNA was higher than 0.03 mg·L^(−1),it could have a short-term irreversible effect on the normal denitrification of sludge,being the result of the combined action of concentration and duration.When FNA was lower than 0.01 mg·L^(−1),high nitrite concentration also inhibited denitrification.But the inhibition can be reversed by sludge washing,or even only by the domestication of sludge itself.During denitrification,microorganisms had an ability to spontaneously adjust the pH of the environment within a certain range.The alkalinity change in the system during denitrification was affected by the carbonate buffer system.The higher the pH,the better the water buffering ability.