原水水质对输水管道硝化作用形成的影响

采用配制水样模拟Ⅱ类、Ⅲ类和劣Ⅴ类地表水,利用管道模拟反应器研究不同原水水质条件下输水管道中硝化作用的形成及对输水水质的影响.结果表明:原水中氨氮(NH4+-N)及溶解氧(DO)含量对NH4+-N去除均有一定影响,DO充足时,去除率随原水中NH4+-N含量的增加而增加,DO浓度低时,DO成为影响NH4+-N去除的主要因素;原水NH4+-N含量对运行初期NO2--N积累有重要影响,NH4+-N含量越高,NO2--N积累量越大,随着生物膜的成熟,影响作用逐渐减弱;反应器中AOB数量主要受原水NH4+-N浓度的影响,随NH4+-N浓度升高而增加;NOB数量受NH4+-N和DO浓度的双重影响,DO含量低会抑制NOB活性,使NOB数量减少,导致NO2--N积累;输水管道中的硝化作用是水中及生物膜中硝化细菌共同作用的结果,但生物膜中硝化细菌存在水平高,其硝化作用占主导地位.

Effect of raw water quality on formation of nitrification in water distribution pipes

Effect of raw water quality on nitrification formation and its influence on effluent in water distribution pipes were studied by pipeline reactors simulated the water situation. Water samples were prepared in laboratory to simulate ClassⅡ, Class Ⅲ and Class Ⅴof the surface water standard. The results showed that the concentration of ammonia nitrogen (NH4+-N) and dissolved oxygen (DO) in raw water had significant effect on NH4+-N removal. Under sufficient DO, removal rate of NH4+-N improved with the increasing NH4+-N concentration in raw water. When DO was insufficient, NH4+-N removal was limited by DO. Accumulation of nitrite nitrogen (NO2--N) was significantly affected by concentration of NH4+-N in raw water at initial stage of biofilm formation. NO2--N accumulated more serious with higher NH4+-N content, but the influence gradually weakened as the biofilm matured. The quantity of AOB was considerably affected by concentration of NH4+-N in raw water, and AOB quantity increased with the concentration of NH4+-N. The quantity of NOB was considerably affected by the concentration of both NH4+-N and DO in raw water. Low DO concentration would inhibit activity of NOB, resulted in fewer quantity of NOB and less accumulation of NO2--N. Nitrification in water distribution pipes was generated by nitrifying bacteria in the bulk water and biofilm, but biofilm nitrify bacteria had a higher level than bulk nitrify bacteria.