National University of Singapore, Sembcorp-NUS Corporate Laboratory c/o FoE, Block E1A, #04-01, 1 Engineering Drive 2, Singapore 117576; Department of Civil & Environmental Engineering, Faculty of Engineering, National University of Singapore, Block E1A, #07-01, 1 Engineering Drive 2, Singapore 117576.
National University of Singapore, Sembcorp-NUS Corporate Laboratory c/o FoE, Block E1A, #04-01, 1 Engineering Drive 2, Singapore 117576; Department of Mechanical Engineering, Faculty of Engineering, National University of Singapore, Block EA, #07-08, 9 Engineering Drive 1, Singapore 117575.
Water Res. 2021 Sep 15;203:117504. doi: 10.1016/j.watres.2021.117504. Epub 2021 Aug 3.
An integrated computational fluid dynamics (CFD)-kinetic model framework was developed to numerically describe the hydrodynamic and kinetic phenomena in a liquid-solid two phases Fluidized-bed reactor Fenton/granular activated carbon (FBR-Fenton/GAC) system. The model obtained excellent accuracy for predicting chemical oxygen demand (COD) removal in reverse osmosis concentrate (ROC) treatment under different operation conditions. Hydrodynamic evaluation demonstrated that under the quasi-steady state, the GAC particles were uniformly circulated in the bed region with two pairs of counter-rotating recirculation cells, and a clear interface layer formed between the solid and the liquid phases. Superficial liquid velocity highly affected the fluidized bed expansion and solid volume fraction, while its impact on the overall COD removal efficiency was negligible. Chemical evaluation revealed that GAC/HO catalytic reaction enhanced the OH production in FBR-Fenton/GAC process by 2.7 folds as compared to homogenous Fenton process. Fenton reaction mainly occurred in the upper liquid region and its kinetics for OH generation significantly diminished by 75% within the first 10 min. GAC/HO reaction took place in the fluidized bed region for continuous OH generation with a relatively stable rate from 1.21 × 10 to 0.60 × 10 M/s. Along the ROC treatment with FBR-Fenton/GAC process, the simulated COD degradation rate decreased along the reaction time with 2.05 × 10 M/s and 2.93 × 10 M/s at 2 min and 60 min, respectively. Faster COD removal was attained in the fluidized bed region due to combining effects of OH oxidation and GAC adsorption. The overall predicted COD concentration reduced from 122 to 35 mg/L, OH oxidation and GAC adsorption contributed 59% and 41%, respectively, to the total COD removal.
建立了一个集成的计算流体动力学（CFD）-动力学模型框架，用于数值描述固液两相流化床反应器芬顿/颗粒活性炭（FBR-Fenton/GAC）系统中的流体动力学和动力学现象。该模型在预测反渗透浓缩物（ROC）处理中不同操作条件下的化学需氧量（COD）去除方面具有出色的准确性。水动力评估表明，在准稳态下，活性炭颗粒在床区均匀循环，形成两对反向旋转的再循环单元，固相与液相之间形成清晰的界面层。表面液体速度对流化床膨胀和固体体积分数有很大影响，而对整体 COD 去除效率的影响可以忽略不计。化学评估表明，与均相芬顿工艺相比，GAC/HO 催化反应使 FBR-Fenton/GAC 工艺中的 OH 生成量增加了 2.7 倍。芬顿反应主要发生在上部液体区，OH 生成动力学在最初 10 分钟内显著降低了 75%。GAC/HO 反应在流化床区进行，持续生成 OH，其生成速率相对稳定，从 1.21×10 到 0.60×10 M/s。随着 ROC 与 FBR-Fenton/GAC 工艺的处理，模拟的 COD 降解率随着反应时间的延长而降低，分别在 2 分钟和 60 分钟时达到 2.05×10 M/s 和 2.93×10 M/s。由于 OH 氧化和 GAC 吸附的结合作用，在流化床区实现了更快的 COD 去除。总体预测 COD 浓度从 122 降至 35 mg/L，OH 氧化和 GAC 吸附分别对总 COD 去除贡献 59%和 41%。
