Drinking Water Research Group, Department of Civil & Mineral Engineering, University of Toronto, Ontario, M5S 1A4, Canada.
Drinking Water Research Group, Department of Civil & Mineral Engineering, University of Toronto, Ontario, M5S 1A4, Canada.
Water Res. 2020 Sep 15;183:116065. doi: 10.1016/j.watres.2020.116065. Epub 2020 Jun 20.
Granular activated carbon (GAC) is widely used by drinking water treatment plants in the Great Lakes region to control 2-methylisoborneol (MIB) and geosmin associated with summertime algal blooms. Recently, however, taste and odour events are being detected in the winter, but there is limited information in the literature about the effect of temperature on GAC performance. In this study, batch isotherm experiments were conducted at 4 °C, 10 °C, and 20 °C to evaluate the temperature impact on adsorption thermodynamics. Pilot-scale column tests were then performed at the same temperatures to evaluate the temperature effect on overall removal, including both thermodynamics and kinetics. The pore and surface diffusion model (PSDM) was applied to fit the experimental data of the pilot-scale column tests, which allowed the kinetic parameters to be determined at each temperature. The isotherm results showed that water temperature did not have a significant effect on the equilibrium adsorption capacity (i.e., the thermodynamics) for MIB and geosmin under the conditions tested, but the pilot tests showed an increased removal of MIB and geosmin by 20-30% at 20 °C compared to the lower temperatures. This demonstrates that water temperature has more impact on kinetics than thermodynamics. Numerical simulations showed that the overall external mass transfer coefficient, K, had the greatest impact on breakthrough. An exponential equation was proposed to correlate temperature and K, and it could be incorporated into a site-specific PSDM to predict the removals of MIB and geosmin in GAC contactors at different temperatures. The model could then be used by a utility, for example, to predict the required increase in empty bed contact time needed to control taste and odour in the winter to the same extent as in the summer.
颗粒活性炭（GAC）被广泛应用于大湖区的饮用水处理厂，以控制与夏季藻类大量繁殖有关的 2-甲基异莰醇（MIB）和土臭素。然而，最近在冬季也检测到了异味事件，但文献中关于温度对 GAC 性能影响的信息有限。在本研究中，在 4°C、10°C 和 20°C 下进行了批量等温实验，以评估温度对吸附热力学的影响。然后在相同温度下进行了中试柱试验，以评估整体去除率的温度效应，包括热力学和动力学。采用孔隙和表面扩散模型（PSDM）对中试柱试验的实验数据进行拟合，从而确定了各温度下的动力学参数。等温实验结果表明，在所测试的条件下，水温对 MIB 和土臭素的平衡吸附容量（即热力学）没有显著影响，但中试试验表明，与较低温度相比，20°C 时 MIB 和土臭素的去除率增加了 20-30%。这表明水温对动力学的影响大于热力学。数值模拟表明，总外部传质系数 K 对穿透曲线的影响最大。提出了一个指数方程来关联温度和 K，并可将其纳入特定地点的 PSDM 中，以预测不同温度下 GAC 接触器中 MIB 和土臭素的去除率。该模型可被公用事业公司用于预测在冬季控制异味所需的空床接触时间增加量，使其与夏季的控制效果相当。
