Greater Copenhagen Utility HOFOR, Parkstien 10, 2450, Copenhagen, Denmark; Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, 1871 Frederiksberg, Denmark.
Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, 1871 Frederiksberg, Denmark.
Water Res. 2021 Oct 15;205:117610. doi: 10.1016/j.watres.2021.117610. Epub 2021 Aug 27.
Phytotoxins - toxins produced by plants - are contaminants with the potential to impair drinking water quality. They encompass a large group of toxic, partially persistent compounds that have been detected in seepage waters and in shallow wells used for drinking water production. If phytotoxins enter wells used for drinking water production, it is essential to know if the drinking water treatment processes will remove them from the water phase. However, it is currently unknown whether phytotoxins remain stable during traditional groundwater treatment using sand filters as the main treatment process. The objective of this study is to investigate removal potential of phytotoxins in biological sand filters and to asses if the removal potential is similar at different waterworks. Microcosms were set up with filter sand and drinking water collected at different groundwater-based waterworks. To be able to monitor phytotoxin removal ptaquiloside, caudatoside, gramine, sparteine, jacobine N-oxide, senecionine N-oxide and caffeine were applied at initial concentrations of 300 µg L, which is approx. two orders of magnitude higher than currently detected in environment, but expected to cover extreme environmental conditions. Removal was monitored over a period of 14 days. Despite the high initial concentration, all filter sands removed ptaquiloside and caudatoside completely from the water phase and at waterworks where pellet softening was implemented (pH 8.4) prior to rapid sand filtration, complete removal occurred within the first 30 min. All filter sands removed gramine and sparteine, primarily by a biological process, while jacobine N-oxide, senecionine N-oxide and caffeine were recalcitrant in the filter sands. During degradation of ptaquiloside and caudatoside we observed formation and subsequent removal of degradation products pterosin B and A. Filter sands with the highest removal potential were characterised by high contents of deposited iron and manganese oxides and hence large specific surface areas. Difference between bacterial communities investigated by 16S rRNA gene analyses did not explain different removal in the filter sands. All five investigated filter sands showed similar degradation patterns regardless of water chemistry and waterworks of origin. In drinking water treatment systems biological sand filters might therefore remove phytotoxin contaminants such as ptaquiloside, caudatoside, gramine, sparteine, while for other compounds e.g. jacobine N-oxide, senecionine N-oxide further investigations involving more advanced treatment options are needed.
植物毒素 - 由植物产生的毒素 - 是有可能损害饮用水质量的污染物。它们包含一大类有毒、部分持久的化合物，这些化合物已在渗漏水和用于饮用水生产的浅层井中检测到。如果植物毒素进入用于饮用水生产的井中，就必须知道饮用水处理过程是否会将其从水相中去除。然而，目前尚不清楚在使用砂滤作为主要处理工艺的传统地下水处理过程中，植物毒素是否保持稳定。本研究的目的是研究生物砂滤器对植物毒素的去除潜力，并评估不同水厂的去除潜力是否相似。使用不同地下水水厂采集的过滤砂和饮用水建立微宇宙。为了能够监测植物毒素去除，将 ptaquiloside、caudatoside、gramine、sparteine、jacobine N-oxide、senecionine N-oxide 和咖啡因以 300µg L 的初始浓度应用，这大约是目前在环境中检测到的浓度的两个数量级，但预计可以覆盖极端环境条件。在 14 天的时间里监测去除情况。尽管初始浓度很高，但所有滤砂都完全从水中去除了 ptaquiloside 和 caudatoside，并且在进行快速砂滤之前在投加软化剂（pH8.4）的水厂，在 30 分钟内完全去除。所有滤砂都通过生物过程主要去除了 gramine 和 sparteine，而 jacobine N-oxide、senecionine N-oxide 和咖啡因在滤砂中则难以去除。在 ptaquiloside 和 caudatoside 的降解过程中，我们观察到降解产物 pterosin B 和 A 的形成和随后的去除。去除能力最强的滤砂的特点是具有高含量的沉积铁和锰氧化物，因此具有较大的比表面积。通过 16S rRNA 基因分析研究的细菌群落之间的差异并不能解释滤砂之间的不同去除。无论水化学和水厂来源如何，所有五种被调查的滤砂都表现出相似的降解模式。因此，在饮用水处理系统中，生物砂滤器可能会去除 ptaquiloside、caudatoside、gramine、sparteine 等植物毒素污染物，而对于其他化合物（例如 jacobine N-oxide、senecionine N-oxide），则需要进一步调查涉及更先进处理选项的研究。
