Department of Environmental Science, Aarhus University, Frederiksborgsvej 399, Roskilde 4000, Denmark; WATEC - Centre for Water Technology, Aarhus University, Ny Munkegade 120, Aarhus 8000, Denmark.
Department of Environmental Science, Aarhus University, Frederiksborgsvej 399, Roskilde 4000, Denmark.
Water Res. 2020 Nov 1;186:116389. doi: 10.1016/j.watres.2020.116389. Epub 2020 Sep 3.
Conventional wastewater treatment lacks the ability to remove many pharmaceuticals. This is leading to emissions to the natural aquatic environment, where these compounds pose a risk to the aquatic organisms. An advanced wastewater treatment technique that has shown promising results is Moving Bed Biofilm Reactors (MBBR). Initial degradation velocity and degradation rate constants of the pharmaceuticals are important parameters for designing an optimal MBBR system; however, the degradation efficiency varies across studies and one of the most plausible causes might be initial concentration. Thus, to verify the effect of initial concentration, the degradation of a mixture of 18 pharmaceuticals at different initial concentrations was studied. For this study MBBR's with very low BOD loading were used as they were conditioned with effluent water. The experiment was set up as a MBBR batch incubation, using effluent wastewater as medium, spiked with the 18 pharmaceuticals in seven different concentration levels (approximately 0-300 µg L). The degradation of 14 out of 18 pharmaceuticals was concentration-dependent. The initial degradation velocity of the pharmaceuticals was either proportional to the initial concentration or was following a typical Michaelis-Menten kinetic. The degradation velocity of one compound, i.e., sulfamethizole might have been inhibited at high concentrations. The degradation rate constants from single first-order fittings (K) for some compounds deviated from the expected behavior at low concentrations (below 10 µg L). This is suggested to be caused by simplicity of the Michaelis-Menten model, not taking possible occurrence of co-metabolism and mass-transfer limitations into account at low concentrations. This study underlines the fact that K values cannot be interpreted without paying attention to the tested concentration level. Furthermore, it shows that the used MBBRs was able to handle high concentrations of pharmaceuticals, and that the most efficient removal occurs at concentrations above 100 µg L.
传统的废水处理方法缺乏去除许多药物的能力。这导致这些化合物排放到自然水生环境中，对水生生物构成了风险。一种已经显示出有前景的先进废水处理技术是移动床生物膜反应器（MBBR）。药物的初始降解速度和降解速率常数是设计最佳 MBBR 系统的重要参数；然而，降解效率因研究而异，最合理的原因之一可能是初始浓度。因此，为了验证初始浓度的影响，研究了不同初始浓度下 18 种药物混合物的降解情况。在这项研究中，使用了非常低 BOD 负荷的 MBBR，因为它们是用废水条件处理的。该实验是作为 MBBR 批量孵育进行的，使用废水作为培养基，在七个不同浓度水平（约 0-300μg/L）下用 18 种药物进行了加标。18 种药物中的 14 种的降解与浓度有关。药物的初始降解速度要么与初始浓度成正比，要么遵循典型的米氏动力学。一种化合物，即磺胺甲恶唑的降解速度可能在高浓度下受到抑制。一些化合物的单一级拟合（K）的降解速率常数在低浓度（低于 10μg/L）时偏离了预期行为。这被认为是由于米氏-门坦模型的简单性所致，在低浓度下没有考虑可能发生的共代谢和质量传递限制。这项研究强调了这样一个事实，即如果不注意测试的浓度水平，就不能解释 K 值。此外，它表明所使用的 MBBR 能够处理高浓度的药物，并且在浓度高于 100μg/L 时，去除效率最高。
