Batstone D J, Torrijos M, Ruiz C, Schmidt J E
Environment and Resources, DTU, The Technical University of Denmark, Lyngby 2800, Denmark.
Water Sci Technol. 2004;50(10):295-303.
The model structure in anaerobic digestion has been clarified following publication of the IWA Anaerobic Digestion Model No. 1 (ADM1). However, parameter values are not well known, and uncertainty and variability in the parameter values given is almost unknown. Additionally, platforms for identification of parameters, namely continuous-flow laboratory digesters, and batch tests suffer from disadvantages such as long run times, and difficulty in defining initial conditions, respectively. Anaerobic sequencing batch reactors (ASBRs) are sequenced into fill-react-settle-decant phases, and offer promising possibilities for estimation of parameters, as they are by nature, dynamic in behaviour, and allow repeatable behaviour to establish initial conditions, and evaluate parameters. In this study, we estimated parameters describing winery wastewater (most COD as ethanol) degradation using data from sequencing operation, and validated these parameters using unsequenced pulses of ethanol and acetate. The model used was the ADM1, with an extension for ethanol degradation. Parameter confidence spaces were found by non-linear, correlated analysis of the two main Monod parameters; maximum uptake rate (k(m)), and half saturation concentration (K(S)). These parameters could be estimated together using only the measured acetate concentration (20 points per cycle). From interpolating the single cycle acetate data to multiple cycles, we estimate that a practical "optimal" identifiability could be achieved after two cycles for the acetate parameters, and three cycles for the ethanol parameters. The parameters found performed well in the short term, and represented the pulses of acetate and ethanol (within 4 days of the winery-fed cycles) very well. The main discrepancy was poor prediction of pH dynamics, which could be due to an unidentified buffer with an overall influence the same as a weak base (possibly CaCO3). Based on this work, ASBR systems are effective for parameter estimation, especially for comparative wastewater characterisation. The main disadvantages are heavy computational requirements for multiple cycles, and difficulty in establishing the correct biomass concentration in the reactor, though the last is also a disadvantage for continuous fixed film reactors, and especially, batch tests.
国际水协厌氧消化模型第1号（ADM1）发布后，厌氧消化的模型结构已得到明确。然而，参数值并不为人熟知，而且所给出的参数值中的不确定性和变异性几乎无人知晓。此外，用于参数识别的平台，即连续流实验室消化器和批次试验，分别存在运行时间长和难以定义初始条件等缺点。厌氧序批式反应器（ASBR）按进水 - 反应 - 沉淀 - 排水阶段进行排序，由于其本质上行为具有动态性，并且允许通过可重复行为来建立初始条件和评估参数，因此为参数估计提供了有前景的可能性。在本研究中，我们利用测序运行的数据估计了描述酿酒厂废水（大部分化学需氧量以乙醇形式存在）降解的参数，并使用未测序的乙醇和乙酸脉冲对这些参数进行了验证。所使用的模型是ADM1，并对乙醇降解进行了扩展。通过对两个主要莫诺德参数（最大摄取速率（k(m)）和半饱和浓度（K(S)））进行非线性相关分析，找到了参数置信区间。仅使用测得的乙酸盐浓度（每个周期20个数据点）就可以共同估计这些参数。通过将单周期乙酸盐数据内插到多个周期，我们估计对于乙酸盐参数，在两个周期后可实现实际的“最佳”可识别性，对于乙醇参数则在三个周期后实现。所找到的参数在短期内表现良好，并且能很好地反映乙酸盐和乙醇的脉冲（在酿酒厂进水周期的4天内）。主要差异在于对pH动态的预测较差，这可能是由于存在一种未识别的缓冲剂，其总体影响与弱碱（可能是碳酸钙）相同。基于这项工作，ASBR系统对于参数估计是有效的，特别是对于比较废水特性而言。主要缺点是多个周期的计算量很大，并且难以确定反应器中正确的生物质浓度，不过最后这一点对于连续固定膜反应器尤其是批次试验来说也是一个缺点。
