Department of Civil and Environmental Engineering, Western University, London, ON, Canada.
Bishop Water Inc., Arnprior, ON, Canada.
Water Environ Res. 2024 Nov;96(11):e11150. doi: 10.1002/wer.11150.
Biofilm modeling is inherently complex, often requiring multiple assumptions and simplifications. In biofilm modeling, default or literature-based values in biofilm systems are usually used to estimate biofilm parameters, including boundary layer, biofilm density, thickness, attachment, and detachment rates. This study aimed to characterize and model the biofilm of a specific rope-type fixed media system, removing carbon and total inorganic nitrogen, coupled with sensitivity analysis. Among the five model parameters, the sensitivity analysis of this study showed that boundary layer thickness is the most influential parameter for predicting effluent ammonia and nitrate concentrations, and biofilm density is most sensitive with respect to effluent chemical oxygen demand (COD). The least sensitive parameter is the detachment rate. Based on the calculated mean absolute error (MAE) and root mean squared error (RMSE), the calibrated BioCord fixed-film reactor (BFFR) model accurately predicted effluent ammonium and dissolved oxygen (DO) in the continuously aerated bench-scale reactor (R1) and failed to predict well in the intermittently aerated bench-scale reactor (R2). RMSE values calculated for NH-N and DO in R1 are 0.95 and 0.53 mg/L, respectively. In the BioCord pilot plant's case, ammonium-N predicted by the model fit the measured values well, while it overpredicted DO concentrations. PRACTITIONER POINTS: Fixed biofilm BioCord reactors were studied for primary effluent treatment. A methodology was developed to characterize biofilms. Boundary layer thickness is the most influential parameter for predicting effluent ammonia and nitrate concentrations. Biofilm density is the most sensitive parameter with respect to effluent COD. The calibrated BFFR model can predict effluent ammonium, nitrite, and nitrate-nitrogen.
生物膜建模本质上很复杂，通常需要进行多项假设和简化。在生物膜建模中，通常使用生物膜系统中的默认值或文献值来估算生物膜参数，包括边界层、生物膜密度、厚度、附着和脱落速率。本研究旨在对特定绳式固定介质系统的生物膜进行特征描述和建模，同时去除碳和总无机氮，并结合敏感性分析。在这五个模型参数中，本研究的敏感性分析表明，边界层厚度是预测出水氨氮和硝酸盐浓度的最具影响力的参数，而生物膜密度对出水化学需氧量（COD）最敏感。最不敏感的参数是脱落速率。基于计算得到的平均绝对误差（MAE）和均方根误差（RMSE），经过校准的 BioCord 固定膜生物反应器（BFFR）模型能够准确预测连续曝气的台式规模反应器（R1）中的出水氨氮和溶解氧（DO），但在间歇曝气的台式规模反应器（R2）中的预测效果不佳。R1 中 NH-N 和 DO 的 RMSE 值分别为 0.95 和 0.53mg/L。在 BioCord 中试工厂的案例中，模型预测的氨氮值与实测值吻合较好，而 DO 浓度则存在高估。实用要点：本研究考察了固定生物膜 BioCord 反应器对原水的处理效果。开发了一种用于生物膜特征描述的方法。边界层厚度是预测出水氨氮和硝酸盐浓度的最具影响力的参数。生物膜密度是对出水 COD 最敏感的参数。经校准的 BFFR 模型可预测出水氨氮、亚硝酸盐和硝酸盐氮。
