基于硫化物硝酸菌抑制的城市污水单级自养脱氮工艺研究

采用外循环序批式反应器(ECSBR),通过向反应器中分阶段投加硫化物,成功抑制体系中亚硝酸氧化菌(NOB)的活性,实现了城市污水单级短程硝化/厌氧氨氧化自养生物脱氮,出水氨氮为3.78 mg·L-1,氨氮去除率为88.4％,氮去除负荷为66.8 g·m-3·d-1.在投加硫化物前,系统氮转化途径以全程硝化为主,出水硝酸盐为13 ～22 mg·L-1,生成硝态氮与去除氨氮比值＞0.9.在投加硫化物后,NOB的活性受到了抑制,出水硝酸盐降为4.18 mg·L-1,生成硝酸盐与去除氨氮比值平均为0.17.体系中大量的氮以氮气的形式被去除,占进水氮的65.4％.氮转化途径由全程硝化向短程硝化/厌氧氨氧化耦合脱氮转化.研究还表明,硫化物对于体系NOB的抑制是可逆的,停止投加硫化物后,NOB的活性又重新恢复.因此,分阶段投加硫化物能保证反应过程中对NOB的持续抑制作用,为实现单级自养脱氮工艺的快速启动和稳定维持提供了一种新的策略.

Nitrite-oxidizing bacteria (NOB) inhibition by pulse sulfide doses in single-stage autotrophic biological nitrogen removal process for municipal wastewater treatment

An external circulation sequencing batch reactor (ECSBR) was developed to investigate the autotrophic nitrogen removal from municipal wastewater based on a combined partial nitrification and anaerobic ammonium oxidation (ANAMMOX) process. Pulse dosing sulfide to ECSBR was applied to inhibit nitrite-oxidizing bacteria (NOB). The results showed that the NH₄⁺-N concentration of effluent was below 3.78 mg·L^-1, the removal efficiency was 88.4%, and the total nitrogen removal rate reached 66.8 g·m^-3·d^-1. Before dosing sulfide, a complete nitrification dominated in reactor with a nitrate concentration of 13~22 mg·L^-1 in the effluent, and the molar ratio of produced NO₃^--N to consumed NH₄⁺-N was more than 0.9. After sulfide was pulse dosed to reactor, the NOB activity was efficiently inhibited and the effluent NO₃^--N was reduced to 4.18 mg·L^-1. The molar ratio of produced NO₃^--N to consumed NH₄⁺-N decreased to 0.17. Most of the influent N was removed in the form of N₂, which accounted for 65.4% of the influent N. A partial nitrification associated with ANAMMOX process became the dominant reaction after pulse dosing sulfide. It was also found that NOB inhibition caused by sulfide was reversible that the NOB activity could recover when the sulfide was no longer exposed. The pulse sulfide application can ensure the constant inhibition of sulfide on NOB during operation, which resulted in a better performance and a rapid start-up of the one-stage autotrophic nitrogen removal process.