不同有机负荷下氮缺乏对活性污泥膨胀的影响

EXPLORING THE EFFECTS OF NITROGEN DEFICIENCY ON THE SLUDGE BULKING AT DIFFERENT ORGANIC LOADING

有机负荷与营养物缺乏是活性污泥处理工艺中引起污泥膨胀的 2个重要因素。本文研究了在低有机负荷条件下氮缺乏对活性污泥膨胀的影响。试验结果表明 ,营养物充足时 ,低有机负荷下并不一定发生污泥膨胀 ,并且反应过程中发生不完全的硝化反应。当进水中缺氮时 ,低有机负荷下 ,由于微生物对自身细胞物质的分解代谢作用 ,剩余污泥量减少 ,代谢产物中的营养物质在一定程度上缓解了进水中氮缺乏的影响 ,使得污泥沉降性能恶化程度并不严重。同时 ,还对污泥膨胀的控制与恢复进行了研究。

The present paper intends to explore the possible effects of nitrogen deficiency on the sludge bulking at low organic loading. As is known, organic loading and nutrient deficiency are two important factors influencing the sludge bulking in sequencing batch reactor processing fed with brewing wastewater. To solve this problem, it is necessary to keep the necessary value of biochemical oxygen demand: nitrogen (BOD/N) in the influent at 100/5, 100/2, 100/0.94 respectively. However, since the organic loading keeps changing with the reaction time, sludge bulking takes place when the nitrogen is deficient. Our experimental results indicate that non filamentous bulking could be observed if nitrogen was insufficient at usual organic loading. Moreover, the more serious the degree of nitrogen deficiency was, the more serious the degree of non filamentous bulking would be. However, sludge bulking will not surely occur when the nutrient is sufficient at low loading. Only incomplete nitrification occurs, which might be the main cause for no sludge bulking occurrence at low organic loading. Our experiments prove that when influent nitrogen was insufficient at low organic loading, if the organic loading dropped gradually from 1.54 kg COD/(kgMLSS·d) to 0.62 kg COD/(kgMLSS·d), sludge bulking didn't occur. When the value of influent BOD/N was 100/2, non filamentous sludge bulking would occur at the normal organic loading. However, at low organic loading, when SVI amounted to 140 mL/g, the sludge bulking would occur. When the value of influent BOD/N was 100/0.94, serious non filamentous sludge bulking occurred even at the normal organic loading but at low organic loading. Nevertheless, when SVI increased above 200 mL/g, non filamentous bulking was observed. Thus, it can be inferred that it must be the catabolism of microorganism cellular material that leads to the decrease of MLSS concentration with the nutrient release from the metabolic product and the delayed effect of the nitrogen deficiency, which may account for the declining of the deteriorate degree of sludge settling. To prove our deduction, experiments were done to control of the sludge bulking, whose results indicate that after putting sufficient nitrogen into the influent and increasing the organic loading, the sludge bulking could be controlled effectively and the sludge could be activated and resumed desirably.