不同曝气量对SBBR短程硝化微生物特性及氮转化的影响

在实验室规模的序批式生物膜反应器(SBBR)中研究了不同曝气量(7.2、12.0、15.6L·h-1,对应反应器中平均溶解氧浓度分别为0.5、0.8、1.2mg·L-1)下生物膜的生物特性变化及短程硝化过程规律.结果表明:减小曝气量使反应器内溶解氧浓度降低,将导致生物膜的总生物量下降,生物膜中氨氧化菌逐渐成为优势菌,无论数量还是生物活性均高于亚硝酸氧化菌,利于亚硝酸盐积累;在一个反应周期中,生物膜对溶解氧需求的分配是不同的,曝气初期溶解氧主要用于异氧菌对COD的降解,其后用于氨氮转化.根据上述规律,提出在短程硝化过程中采用"梯级递减式曝气"供氧新策略,即在反应初期保持一种较大的曝气量,提高反应器溶解氧浓度,促进COD快速降解,随后保持一种小曝气量使反应器中溶解氧维持较低的浓度,从而促进亚硝酸盐积累及优化供氧效率.

Effect of aeration flow on microbial characteristics and nitrogen transformation of shortcut nitrification processing in a sequencing batch biofilm reactor

A laboratory-scale sequencing batch biofilm reactor (SBBR) was used to investigate characteristics of biofacies and correlative performance of shortcut nitrification process under different aeration flows of 7.2 L·h^-1, 12.0 L·h^-1and 15.6 L·h^-1 (corresponding with averaged dissolved oxygen concentration of around 0.5 mg·L^-1, 0.8 mg·L^-1 and 1.2 mg·L^-1). The experimental results showed that total biomass of biofilm in SBBR substantially reduced with decreased dissolved oxygen concentration during the aerobic phase. The ammonia-oxidizing bacteria (AOB) became the dominant population in the system at low dissolved oxygen concentration. Both number and biological activity of AOB were relatively higher than that of nitrite-oxidizing bacteria (NOB) that resulted in nitrite accumulation. The dissolved oxygen demand during the whole cyclic treatment was not uniform. At the early stage of the aeration phase, dissolved oxygen was preferentially consumed by heterotrophic bacteria for COD degradation. Then it was utilized for ammonia oxidation. Based on the results, we proposed Multi-section Declining Aeration (MSDA) as an improved aeration mode for the shortcut nitrification processing. In MSDA mode, initial high aeration flow was supplied to enhance COD degradation. Thereafter, aeration flow was switched down to maintain low dissolved oxygen concentration which could facilitate nitrosification for nitrite accumulation and optimize energy consumption.