同步硝化反硝化的持续稳定与供氧模式的关系

Relations of Sustained Stable Simultaneous Nitrification and Denitrification to Modes of Oxygen Supply

为考察同步硝化反硝化(SND)的持续稳定性,以模拟污水为试验对象,于SBR反应器内研究了不同供氧模式下SND过程中氮转化规律和DO、ORP及pH值的变化规律。试验结果表明,恒定气量连续曝气(CA)模式下,SND持续稳定的时间及对TN的去除率随曝气量的增加而减小,DO、ORP和pH值的曲线上均出现了预示SND过程结束而完全硝化反应开始的折点;在恒定气量间歇曝气(IA)模式下,随曝气百分数(AF)的降低,DO、ORP和pH值的曲线上不仅没有折点出现而且均呈现趋于平直、稳定的趋势,同时对TN的去除率相应增加;在恒定DO浓度连续曝气模式下,当DO浓度从2.0 mg/L降至0.5 mg/L时,ORP和pH值的波动逐渐趋于稳定且对TN的去除率也随之增加。对上述试验结果进行分析可知,具有低AF的IA和恒定低DO浓度的CA两种模式,不仅有利于低碳城市污水SND过程的持续稳定,而且还可节省曝气量。

To investigate the sustained stability of simultaneous nitrification and denitrification （SND）, the profiles of TN, NO3 - N, NH3 - N, NO2- - N, DO, ORP and pH were investigated in a SBR treating synthetic wastewater under the different oxygen supply modes. The results indicate that under the mode of continuous aeration （CA） with fixed air flux in a cycle, the TN removal rates reduce and the sustained stable time of the SND are reduced with the increasing of air flux, and the breakpoints indicating the end of SND and the beginning of complete nitrification occur in profiles of DO, ORP and pH. Under the mode of intermittent aeration （IA） with fixed air flux in a cycle, with the decreasing of aeration fraction （ AF）, the profiles of DO, ORP and pH tend to be the level and straight lines without any breakpoints, and the TN removal rate is increased. Under the mode of CA with fixed DO concentration, the variation of ORP and pH values tends to be stable, and the TN removal rate is increased when DO is reduced from 2.0 mg/L to 0.5 mg/L. These results suggest that the modes of oxygen supply by IA with small AF and by CA with fixed low DO both are helpful for SND and save oxygen quantity.