养猪废水厌氧消化液SBR短程硝化系统影响因素

Main influence factors for shortcut nitrification in a SBR treating anaerobic digested piggery wastewater

摘要:

针对养猪废水厌氧消化液较高残留的氨氮,为开发短程硝化-反硝化脱氮工艺,以序批式活性污泥反应器(SBR)的运行为基础,探讨温度、氨氮负荷(Rnl)和曝气时间对活性污泥系统短程硝化特征的影响．结果表明: 在28和15 ℃ 条件下,将溶解氧控制为1.0～2.0 mg·L-1时,SBR系统均能实现良好的短程硝化功能;但在15 ℃条件下,氨氮去除率和亚硝酸盐积累率(Rna)较28 ℃均有显著下降,分别从71.1％和96.7％降到52.8％和85.4％;在28 ℃条件下,氨氮负荷由0.56 kg·m-3·d-1大幅提高到2.18 kg·m-3·d-1后,SBR系统的氨氮去除率显著降为48.6％,但Rna仍然高达96.8％,保持了良好的短程硝化性能．Rnl较高时,可适当延长曝气时间以强化SBR系统的氨氮氧化能力. 但曝气时间过长会导致大量NO₂--N的氧化,Rna显著下降．

Abstract:

To develop a shortcut nitrification process for treating anaerobic digested piggery wastewater with a high ammonia concentration, a sequencing batch reactor (SBR) was introduced, and the temperature, ammonia nitrogen loading rate (Rnl) and aeration time were investigated as the significant influence factors of the shortcut nitrification. The shortcut nitrification process could be established in the SBR at 28 ℃ or 15 ℃ with the identical dissolved oxygen (DO), ranged from 1 to 2 mg·L-1. But the ammonia removal and nitrite accumulation rate Rna were decreased from 71.1％ and 96.7％ to 52.8％ and 85.4％, respectively, when the temperature was dropped from 28 ℃ to 15 ℃. Though the ammonia removal rate was decreased to 48.6％ since the Rnl had been increased from 0.56 to 2.18 kg·m-3·d-1 at 28 ℃, a Rna as high as 96.8％ was obtained, indicating that an excellent shortcut nitrification occurred in the SBR. To obtain a superior ammonia oxidation with a higher Rnl, extension of aeration time would be supportive. But an excessive aeration could result in an increase in nitrate and a decrease in Rna, which was unfeasible for the shortcut nitrification process in the SBR.