外源全程硝化污泥对城市污水SPNA系统的影响

为强化城市污水短程硝化-厌氧氨氧化(SPNA)系统脱氮性能与稳定性,在间歇曝气条件下研究投加外源全程硝化污泥对城市污水SPNA系统的影响及机理.结果显示,空白组(SBR3)总氮去除率由35.5%升高至66.3%,短周期分批次投加外源全程硝化污泥(SBR2,投加周期为5d,投加比为2.5%)与长周期分批次投加(SBR1,投加周期为20d,投加比为10%)的SPNA系统总氮去除率分别由31.7%和36.5%升高至76.3%和67.2%,这表明,投加全程硝化污泥有利于提高SPNA系统的脱氮性能,且当投加总量相同时,短周期分批次投加的效果优于长周期分批次投加.功能菌活性结果与脱氮效果一致,SBR1~SBR3的厌氧氨氧化菌(AnAOB)最大活性分别由3.43mg-N/(L·h)升高至7.66,8.19和7.31mg-N/(L·h),氨氧化细菌(AOB)与亚硝酸盐氧化菌(NOB)活性比分别为8.79,9.83和8.78.在间歇曝气条件下投加全程硝化污泥,可选择性抑制NOB、富集AOB,提高AOB与NOB的活性比,利于稳定短程硝化效果,为AnAOB提供稳定的基质,且短周期分批次投加可降低外源硝化污泥中的NOB对系统的冲击,更有利于实现高AOB与NOB活性比,提高系统稳定性.此外,内源短程反硝化菌Candidatus_Competibacter相对丰度明显升高,可为AnAOB提供更多的亚硝酸盐氮,进一步利于AnAOB富集.

Effects of exogenous nitrification sludge on the single - stage partial nitrification - anammox system of municipal sewage

In order to improve the nitrogen removal performance and stability of the single-stage partial nitrification-anammox (SPNA) system treating municipal sewage, the effects and mechanisms of adding exogenous nitrification sludge to mainstream SPNA system were evaluated under intermittent aeration condition. The results showed that the total nitrogen removal efficiency of the control SPNA system (SBR3) increased from 35.5% to 66.3%. The total nitrogen removal efficiencies of SPNA systems with nitrification sludge added in batches in a short cycle (SBR2, the dosing period was 5d, the dosing ratio was 2.5%) and in batches in a long cycle (SBR1, the dosing period was 5d, the dosing ratio was 2.5%) increased from 31.7% and 36.5% to 76.3% and 67.2%, respectively. And the addition of nitrification sludge was beneficial to the nitrogen removal performance of mainstream SPNA system and adding nitrification sludge in batches in a short cycle showed better performance. The maximum activities of anaerobic ammonium oxidation bacteria (AnAOB) in SBR1-SBR3 increased from 3.43mg-N/(L·h) to 7.66, 8.19% and 7.31mg-N/(L·h), respectively, and the activity ratios of ammonia oxidizing bacteria (AOB) and nitrite oxidizing bacteria (NOB) were 8.79, 9.83 and 8.78, respectively. Adding nitrification sludge under intermittent aeration condition could selectively inhibit NOB and enrich AOB, leading to a higher activity ratio of AOB and NOB and more stable partial nitrification, which provided stable substrates for AnAOB. In addition, adding the nitrification sludge in batches in a short cycle could reduce the impact of NOB of exogenous nitrification sludge on the system, which was more conducive to achieve high AOB/NOB activity ratio and improved the stability of system. Moreover, the relative abundance of Candidatus_Competibacter, thought to be the endogenous partial denitrification bacteria, increased obviously, providing AnAOB with more nitrite and was further beneficial to AnAOB enrichment. Therefore, this study provided new ideas for promoting the application of mainstream anammox process.