以模拟城市生活污水为研究对象,比较了SBR单级好氧法在不同pH值条件下(pH=8.0±0.2和pH=6.5±0.2)对氮转化途径的影响.结果表明,运行方式为瞬时进水→曝气(4h)→沉淀间歇(4h)→瞬时出水,2个反应器NH4^+-N进水浓度为25-40mg·L^-1条件下,NH4^+-N转化率均在80%以上.pH为8.0±0.2的反应器内发生了传统的硝化作用,部分NH4^+-N通过同时硝化反硝化作用去除;pH为6.5±0.2的反应器内反应过程中NO2^--N的生成速率近乎为零,NO3^--N的浓度在曝气结束时达到最高值,也仅为1.6mg·L^-1,反应过程中NO2^--N、NO3^--N的浓度没有明显积累;而反应器内废水中总氮(TIN)的去除量为25.75mg·L^-1,泥中氮的增长量约为22.2mg·L^-1,略低于废水中氮的去除量,表明废水中的氮大部分转化到了污泥中,这与传统的脱氮理论有所区别.研究推断,在低pH条件下NH4^+-N的去除主要是通过微生物超量吸收氮源后通过排除富氮污泥来实现的.
The nitrogen removal performance of two SBRs with single aerobic stages were investigated under different pH conditions(R1:pH=8.0±0.2;R2:pH=6.5±0.2)using simulated municipal wastewater.The 8 h cycles consisted of approximately simultaneous influent→aeration(4h)→settle/idle period(4h)→simultaneous effluent.The results showed that the average efficiencies of ammonium removal in both SBRs were above 80% when ammonia in the influent was 25-40 mg · L^-1.Conventional nitrification and denitrification were observed in R1;while little nitrite coupled with a little nitrate was detected in the effluent of R2(the maximal concentration of NO3^--N was only 1.6 mg · L^-1).The amount of total inorganic nitrogen(TIN)removed reached 25.75 mg · L^-1,while the nitrogen accumulation in the activated sludge was only 22.2 mg · L^-1,which was less than the amount of TIN removed.The results implied that nitrogen removal in R2 was attained not by traditional nitrification/denitrification but by the over uptaken-nitrogen sludge.