FHNW University of Applied Sciences and Arts Northwestern Switzerland, School of Life Sciences, Institute for Ecopreneurship, 4132 Muttenz, Switzerland; School of Architecture, Civil and Environmental Engineering (ENAC), Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland.
FHNW University of Applied Sciences and Arts Northwestern Switzerland, School of Life Sciences, Institute for Ecopreneurship, 4132 Muttenz, Switzerland.
Water Res. 2022 Aug 1;221:118785. doi: 10.1016/j.watres.2022.118785. Epub 2022 Jun 21.
Water treatment with nanofiltration (NF) or reverse osmosis (RO) membranes results in a purified permeate and a retentate, where solutes are concentrated and have to be properly managed and discharged. To date, little is known on how the selection of a semi-permeable dense membrane impacts the dissolved organic matter in the concentrate and what the consequences are for micropollutant (MP) abatement and bromate formation during concentrate treatment with ozone. Laboratory ozonation experiments were performed with standardized concentrates produced by three membranes (two NFs and one low-pressure reverse osmosis (LPRO) membrane) from three water sources (two river waters and one lake water). The concentrates were standardized by adjustment of pH and concentrations of dissolved organic carbon, total inorganic carbon, selected micropollutants (MP) with a low to high ozone reactivity and bromide to exclude factors which are known to impact ozonation. NF membranes had a lower retention of bromide and MPs than the LPRO membrane, and if the permeate quality of the NF membrane meets the requirements, the selection of this membrane type is beneficial due to the lower bromate formation risks upon concentrate ozonation. The bromate formation was typically higher in standardized concentrates of LPRO than of NF membranes, but the tradeoff between MP abatement and bromate formation upon ozonation of the standardized concentrates was not affected by the membrane type. Furthermore, there was no difference for the different source waters. Overall, ozonation of concentrates is only feasible for abatement of MPs with a high to moderate ozone reactivity with limited bromate formation. Differences in the DOM composition between NF and LPRO membrane concentrates are less relevant than retention of MPs and bromide by the membrane and the required ozone dose to meet a treatment target.
采用纳滤（NF）或反渗透（RO）膜进行水处理会得到净化后的渗透物和浓缩物，其中溶质被浓缩，必须妥善管理和排放。迄今为止，人们对选择半透致密膜如何影响浓缩物中的溶解有机物以及浓缩物用臭氧处理时对微污染物（MP）去除和溴酸盐形成的影响知之甚少。通过三种膜（两种 NF 和一种低压反渗透（LPRO）膜）从三种水源（两条河水和一个湖水）制备标准化浓缩物进行了实验室臭氧氧化实验。通过调节 pH 值和溶解有机碳、总无机碳、选择具有低至高臭氧反应性的微污染物（MP）和溴化物的浓度来对浓缩物进行标准化，以排除已知会影响臭氧氧化的因素。NF 膜对溴化物和 MPs 的截留率低于 LPRO 膜，如果 NF 膜的渗透物质量符合要求，则选择这种膜类型是有利的，因为浓缩物臭氧氧化时溴酸盐形成的风险较低。在标准化的 LPRO 浓缩物中，溴酸盐的形成通常高于 NF 膜，但在对标准化浓缩物进行臭氧氧化时，MP 去除和溴酸盐形成之间的权衡并不受膜类型的影响。此外，不同水源之间也没有差异。总体而言，浓缩物的臭氧氧化仅适用于去除具有高至中等臭氧反应性的 MPs，同时限制溴酸盐的形成。NF 和 LPRO 膜浓缩物之间 DOM 组成的差异不如膜对 MPs 和溴化物的截留以及达到处理目标所需的臭氧剂量重要。
