Chair of Urban Water Systems Engineering, Technical University of Munich, Am Coulombwall 3, 85748 Garching, Germany.
Berliner Wasserbetriebe, Research and Development, 10864 Berlin, Germany.
Sci Total Environ. 2020 Nov 15;743:140567. doi: 10.1016/j.scitotenv.2020.140567. Epub 2020 Jun 30.
Efficient adsorption of certain trace organic chemicals (TOrCs) present in secondary treated municipal wastewater treatment plant (WWTP) effluents onto granular activated carbon (GAC) has already been demonstrated at lab- and full-scale. Due to high organic matter concentrations in WWTP effluents, GAC filters eventually develop a biofilm and turn into biological activated carbon filters (BAC), where removal of organic compounds is governed by biodegradation as well as by adsorption. However, determining TOrC breakthrough by conducting a long-term BAC column experiment to discern between the removal mechanisms is not possible due to competition for adsorption sites, fluctuating water quality, and other variables. Therefore, a rapid small scale column test (RSSCT) was conducted to determine the contribution of adsorption for select chemicals at 10,000 bed volumes treated (BVT). These results were then used in the pore surface diffusion model (PSDM) to model adsorption behavior at 40,000 BVTs. Pseudo-Freundlich K values obtained from the PSDM model were compared with K values obtained from an integral mass balance calculation. This comparison revealed that the modeling was most accurate for moderately to poorly adsorptive compounds. In comparing RSSCT results to long-term BAC columns, the modeling approach best predicted BAC removal of well adsorbing compounds, such as atenolol, trimethoprim, metoprolol, citalopram, and benzotriazole. However, differences in predicted vs observed BAC removal for the removals of venlafaxine, tramadol and carbamazepine revealed that BAC adsorption capacity was not yet exhausted for these compounds. Therefore, a comparison was not possible. The approach would be improved by operation at longer EBCT and improved calculation of compound fouling indices.
在实验室和全规模范围内，已经证明了高效吸附二级处理城市污水处理厂（WWTP）废水中某些痕量有机化学品（TOrCs）到颗粒活性炭（GAC）上。由于 WWTP 废水中的有机物浓度较高，GAC 过滤器最终会形成生物膜并变成生物活性炭过滤器（BAC），其中有机化合物的去除受生物降解和吸附的共同作用。然而，由于吸附位点的竞争、水质波动和其他变量的影响，通过进行长期 BAC 柱实验来区分去除机制来确定 TOrC 穿透是不可能的。因此，进行了快速小柱试验（RSSCT），以确定在处理 10000 床体积（BVT）时选择化学品的吸附贡献。然后，将这些结果用于孔隙表面扩散模型（PSDM），以在 40000 BVT 时模拟吸附行为。从 PSDM 模型获得的拟-Freundlich K 值与从积分质量平衡计算获得的 K 值进行了比较。比较结果表明，该模型对中等至较差吸附化合物的模拟最为准确。在将 RSSCT 结果与长期 BAC 柱进行比较时，该建模方法最能预测 BAC 对良好吸附化合物（如阿替洛尔、甲氧苄啶、美托洛尔、西酞普兰和苯并三唑）的去除。然而，对于文拉法辛、曲马多和卡马西平的去除，预测的 BAC 去除与观察到的 BAC 去除之间的差异表明，这些化合物的 BAC 吸附容量尚未耗尽。因此，无法进行比较。通过延长 EBCT 和改进化合物污垢指数的计算，可以改进该方法。
