Division of Industrial Electrical Engineering and Automation (IEA), Department of Biomedical Engineering, Lund University, Box 118, SE-221 00 Lund, Sweden.
CAPEC-PROCESS, Department of Chemical and Biochemical Engineering, Technical University of Denmark, Building 229, DK-2800 Lyngby, Denmark.
Water Res. 2015 Mar 1;70:235-45. doi: 10.1016/j.watres.2014.11.035. Epub 2014 Dec 12.
Plant-wide models of wastewater treatment (such as the Benchmark Simulation Model No. 2 or BSM2) are gaining popularity for use in holistic virtual studies of treatment plant control and operations. The objective of this study is to show the influence of ionic strength (as activity corrections) and ion pairing on modelling of anaerobic digestion processes in such plant-wide models of wastewater treatment. Using the BSM2 as a case study with a number of model variants and cationic load scenarios, this paper presents the effects of an improved physico-chemical description on model predictions and overall plant performance indicators, namely effluent quality index (EQI) and operational cost index (OCI). The acid-base equilibria implemented in the Anaerobic Digestion Model No. 1 (ADM1) are modified to account for non-ideal aqueous-phase chemistry. The model corrects for ionic strength via the Davies approach to consider chemical activities instead of molar concentrations. A speciation sub-routine based on a multi-dimensional Newton-Raphson (NR) iteration method is developed to address algebraic interdependencies. The model also includes ion pairs that play an important role in wastewater treatment. The paper describes: 1) how the anaerobic digester performance is affected by physico-chemical corrections; 2) the effect on pH and the anaerobic digestion products (CO2, CH4 and H2); and, 3) how these variations are propagated from the sludge treatment to the water line. Results at high ionic strength demonstrate that corrections to account for non-ideal conditions lead to significant differences in predicted process performance (up to 18% for effluent quality and 7% for operational cost) but that for pH prediction, activity corrections are more important than ion pairing effects. Both are likely to be required when precipitation is to be modelled.
用于处理厂控制和运行整体虚拟研究的废水处理全厂模型（例如基准模拟模型 2 或 BSM2）越来越受欢迎。本研究的目的是展示离子强度（作为活度校正）和离子对在这种废水处理全厂模型中模拟厌氧消化过程的影响。本文使用 BSM2 作为案例研究，使用了许多模型变体和阳离子负荷情况，介绍了改进的物理化学描述对模型预测和整体工厂性能指标（即出水质量指数（EQI）和运行成本指数（OCI））的影响。在用于模拟厌氧消化过程的厌氧消化模型 1（ADM1）中实施的酸碱平衡被修改，以考虑非理想的水相化学。该模型通过 Davies 方法校正离子强度，以考虑化学活度而不是摩尔浓度。开发了一个基于多维牛顿-拉普森（NR）迭代方法的形态分配子程序来解决代数相关性。该模型还包括在废水处理中起重要作用的离子对。本文描述了：1）物理化学校正如何影响厌氧消化器的性能；2）对 pH 值和厌氧消化产物（CO2、CH4 和 H2）的影响；3）这些变化如何从污泥处理传播到水线。在高离子强度下的结果表明，为考虑非理想条件而进行的校正会导致预测过程性能的显著差异（对出水质量的影响高达 18%，对运行成本的影响高达 7%），但对于 pH 值预测，活度校正比离子对效应更重要。当需要模拟沉淀时，两者都可能需要。
