Haider S, Svardal K, Vanrolleghem P A, Kroiss H
Hydrologische Untersuchungsstelle Salzburg (HUS), Austria.
Water Sci Technol. 2003;47(11):203-9.
In lab-scale experiments at the 2-stage activated sludge pilot plant of Vienna's central WWTP it is shown that the wastewater soluble COD concentration, which is inert to a sludge with SRT < 1 d (SI(A)) is about double compared to the S(I) concentration in sludge with SRT > 10 d (SI(B)). Unexpectedly the ratio of SI(A)/SI(B) is independent of the sludge age between SRTs of 0.4 and 1.0 days. The difference between the two S(I) fractions is soluble COD that is readily biodegradable by the sludge with SRT > 10 d. However, it is degraded at a lower maximum growth rate. These results comply with earlier results gained with different methods and at different WWTPs. It is hypothesised that very low sludge ages result in a selection of fast growing bacteria, which can utilise only part of the S(S) in the raw wastewater. The other part of S(S) therefore remains in the wastewater and can thus be utilised for enhanced denitrification in the second stage. It is still unknown beyond which sludge age the soluble inert COD SI(A) starts to decrease, finally reaching the value SI(B) for low loaded systems (SRT > 5 days). From this point on S(I) and S(S) are assumed only to depend on the wastewater composition and not on the sludge age. The assumption of the Activated Sludge Model No.1 that the biodegradable fractions can be modelled as a single substrate and by a single removal kinetic (one Monod term) appears not to be applicable for low sludge ages. Some suggestions for mathematical modelling, design and operation of 2-stage activated sludge systems are given.
在维也纳中央污水处理厂的两级活性污泥中试装置进行的实验室规模实验表明，对于污泥龄（SRT）<1天的污泥呈惰性的废水可溶性化学需氧量（COD）浓度，与污泥龄>10天的污泥中的S(I)浓度相比，约高出一倍。出乎意料的是，SI(A)/SI(B)的比值在0.4至1.0天的污泥龄范围内与污泥龄无关。这两种S(I)组分之间的差异在于，对于污泥龄>10天的污泥而言易于生物降解的可溶性COD。然而，其降解时的最大生长速率较低。这些结果与采用不同方法并在不同污水处理厂获得的早期结果相符。据推测，极低的污泥龄会导致选择生长迅速的细菌，这些细菌只能利用原废水中部分溶解性易生物降解有机物（S(S)）。因此，S(S)的另一部分保留在废水中，从而可用于第二阶段强化反硝化。目前仍不清楚超过何种污泥龄后，可溶性惰性COD SI(A)开始下降，最终达到低负荷系统（SRT>5天）的SI(B)值。从这一点起，假定S(I)和S(S)仅取决于废水成分，而不取决于污泥龄。活性污泥1号模型中关于可生物降解组分可被模拟为单一底物并采用单一去除动力学（一个莫诺德项）的假设，似乎不适用于低污泥龄情况。文中给出了关于两级活性污泥系统数学建模、设计和运行的一些建议。
