超低溶解氧条件下的EBPR系统除磷性能

Phosphorus Removal Performance in EBPR System under Extra-low Dissolved Oxygen Condition

实验采用两个交替厌氧/好氧(An/O)模式运行的SBR反应器,对不同溶解氧(DO)浓度梯度下EBPR系统除磷效果及工艺性能进行了为期127 d的研究.在未控制DO的对照组反应器R1中,好氧段DO≥6 mg·L^(-1),运行的前65 d内工艺除磷性能稳定,除磷率>95.9%,出水总磷<0.5 mg·L^(-1),但由于系统长期处于过曝气状态,65 d后除磷性能逐渐恶化,直至97 d后系统彻底失效,整个运行阶段(1~127 d)出水总磷一级A达标率为39.4%.对于实验组反应器R2,控制好氧段DO浓度分别为2、1、0.5、0.2、0.1 mg·L^(-1),各工况初期除磷性能均有小幅波动,但除磷率迅速回升,继而反应器达到稳定运行.统计发现,实验组反应器R2在整个运行阶段出水总磷一级A的达标率为94.6%,127 d内仅有6 d不达标,工艺性能远优于R1.DO=2 mg·L^(-1)系统的比吸磷速率接近最大值,而低DO条件对比吸磷速率影响较大.实验还发现,尽管由超低DO(0.1 mg·L^(-1))引起的有机物降解速率低导致系统发生污泥微膨胀,但出水总磷仍能100%达标排放,微好氧EBPR的节能除磷具有可行性.

Two sequencing batch reactors（ SBRs） were operated with alternating anaerobic / oxic（ An / O） for 127 days to study the phosphorus removal efficiency and process performance of the EBPR under different dissolved oxygen gradient. For the reactor（ R1） in which DO was not controlled and measured as high as 6 mg·L^（-1） during the aerobic stage,a stable phosphorus removal performance was achieved in the former 65 days during the operational period. The phosphorus removal efficiency was greater than 95. 9% and the total phosphorus in effluent was less than 0. 5 mg·L^（-1）. However,the phosphorus removal performance subsequently deteriorated after 65 days and completely broke up until 97 day due to long-term excessive aeration. Throughout the operational period,only 39. 4% of effluent TP met the national wastewater discharge standard A. For the test reactor（ R2） in which DO was controlled at the levels of 2,1,0. 5,0. 2,0. 1 mg·L^（-1） during the aerobic stage,respectively,the phosphorus removal performance showed a slight fluctuation at the beginning of each stage but rapidly increased to a stable state. According to the statistics,94. 6% of effluent TP in reactor R_2 could meet the national wastewater discharge standard A throughout the operational period. In only 6 days out of the 127 days,effluent TP failed to meet the national standard and the process performance was far better than that of R_1. The specific phosphate uptake rate under DO = 2 mg·L^（-1） was found to be nearly the maximum,but it was greatly influenced by the low DO. In addition,limited filamentous bulking resulted from low organic matter degradation rate under extra-low DO level（ 0. 1 mg·L^（-1）） was observed.Nevertheless,100% of effluent TP during this stage could meet the national standard. As a result,the phosphorus removal in microaerobic EBPR system for saving energy was feasible.