Fe(Ⅱ)对CANON工艺处理城镇污水脱氮性能的影响

Insights into the effects of ferrous ions on nitrogen removal performance of CANON process with synthetic mainstream wastewater treatment

全程自养脱氮(CANON)工艺,作为新型脱氮工艺应用于城镇污水深度脱氮过程中,有望降低污水处理的运行费用。考察了亚铁离子[Fe(Ⅱ)]对CANON工艺启动及稳定运行时脱氮性能的影响。结果表明:15~23℃条件下投加6.3 mg/L Fe(Ⅱ)时,可有效启动并稳定运行CANON工艺处理城镇污水,该工艺氮去除负荷(NRR)、总氮去除率(TNRE)和氨氮去除率(ARE)分别为(4.8±1.1)g-N/(L^(3)·d)、(97±1)%和(44.2±9.3)%;相关性分析表明,通过调控Fe(Ⅱ)投加量可有效抑制亚硝酸盐氧化菌(NOB)的活性;本次优化的Fe(Ⅱ)投加量为6.3 mg/L,其对CANON工艺脱氮性能的影响机制与CANON工艺中功能微生物活性的提高、Fe(Ⅱ)与进水氨氮及其他氮化合物的循环反应、铁型反硝化过程以及铁型厌氧氨氧化过程的耦合有关。

The completely autotrophic nitrogen removal over nitrite(CANON)process as a novel nitrogen removal process was used to the treatment of synthetic mainstream wastewater so as to reduce the treatment cost.The start-up and stable performance of CANON process assisted by ferrous ions(Fe(Ⅱ))was investigated in the present study.The results indicate that the nitrogen removal rate(NRR)reaches(4.8±1.1)g-N/(L^(3)·d)with the help of 6.3 mg/L Fe(Ⅱ)at 15-23℃.Meanwhile,higher total nitrogen removal efficiency(TNRE)and ammonium nitrogen removal efficiency(ARE)of(97±1)%and(44.2±9.3)% are achieved,respectively.The correlation analysis indicates that Fe(Ⅱ)dosing is an efficient regulation strategy for inhibiting nitrite-oxidizing bacteria.The mechanism for the optimized Fe(Ⅱ)level of 6.3 mg/L is related to the improvement of the activity of the functional consortium in the CANON process and the circular reaction of Fe(Ⅱ)with influent ammonia nitrogen and the conversion of other nitrogen compounds by the ferric iron-dependent denitrification process and ferric iron reduction coupled with the anaerobic ammonium oxidation process.