缩短厌氧时间至零后SBR对磷的去除特性

CHARACTERISTICS OF PHOSPHORUS REMOVAL BY SHORTENING ANAEROBIC PERIOD LASTING TIME TO NULL IN SBR

在采用人工废水厌氧-好氧交替运行出现了典型的厌氧释磷、好氧超量摄磷、具有良好的除磷效果的SBR中,不断缩短厌氧时间至只有好氧段,研究反应器对磷的去除特性的变化。结果表明,当进水COD、ρ(NH+4-N)、ρ(PO43--P)分别为100、5、10mg·L-1时,厌氧时间由75min逐步缩短为15、10、5min,释磷几乎在进水的20s内完成,反应器内磷的质量浓度达到28～40.16mg·L-1,在随后的厌氧阶段,继续释磷,好氧段磷的质量浓度迅速降低,出水磷的质量浓度在3.62～5.32mg·L-1之间,磷的去除率由接近100%下降到50%左右;厌氧时间缩短为0min后,进水的同时就开始曝气,但仍然出现释磷,磷的质量浓度达到36.9mg·L-1,在随后135min内液相主体中磷的质量浓度快速降低,微生物对磷的去除率还能达到44%以上。沉淀期(30min)和闲置期(40min)均没有观察到水中磷质量浓度的增加,反应器出现单一好氧生物超量聚磷的现象。经过40d左右的运行,这种单一好氧生物摄磷也没消失,去除率稳定在40%以上。除磷的发生是微生物在进水有机物浓度很低下经过特定诱导,在好氧环境下进水瞬间DO质量浓度的短时略微下降释磷,然后超量摄磷的结果。

Characteristics of phosphorus removal was studied by shortening anaerobic period lasting time to null using synthetic wastewater in a SBR which run under anaerobic-aerobic alternating condition at beginning, appeared the phenomenon of typical phosphorus releasing in anaerobic phase and excess phosphorus absorbing in aerobic phase, and had good phosphorus removal efficiency. Results indicated that when COD to NH4^＋-N to PO4^3--P ratio in the influent was 100 to 5 to 10 mg.L^-1, and anaerobic phase was shorten from 75 min to 15 min to 10 min to 5 min, phosphorus releasing was completed within 20 s and concentration of phosphorus in bulk liquid was 28-40.16 mg.L^-1,and then the PAOs keep on releasing phosphorus; The concentration of phosphorus reduced rapidly in aerobic period and the concentration of phosphorus in effluent was 3.62-5.32 mg .L^-1, the removal rate of phosphorus reduced from 100% to 50%. When anaerobic phase was shorten to null, aeration and influent were at the same time, the phenomenon of phosphorus releasing also appeared, and the concentration of phosphorus in bulk liquid was to 36.9 mg .L^-1, the concentration of phosphorus reduced rapidly in aerobic phase of 135 min and the removal rate of phosphorus was above 44%. During sedimentation phase of 30 min and idle phase of 40 min, concentration of phosphorus in bulk liquid did not increase. This excess biological absorption of phosphorus in sole aerobic phase occurred, and after 40 days operation this phenomenon did not disappear. The phosphorus removal was the result from the inducement of the sludge that even during aerobic period phosphate accumulating organisms （PAOs） could release phosphorus followed feeding instantly due to slightly drop of the dissolved oxygen （DO） and then significantly excess phosphorus uptake.