Haddad Maryam, Barbeau Benoit
NSERC-Industrial Chair on Drinking Water, Polytechnique de Montréal, Montréal, QC H3T 1J4, Canada.
Membranes (Basel). 2019 Jul 19;9(7):90. doi: 10.3390/membranes9070090.
Groundwater (GW) is one of the main potable water sources worldwide. However, the presence of undesirable compounds and particularly manganese (Mn) and iron (Fe) (mainly co-existing in GWs) are considered as objectionable components of potable water for both health and aesthetic issues. As such, individual dwellings supplied by domestic wells are especially threatened by these issues. Current domestic treatment technologies are complicated to operate and even dangerous if improperly maintained (e.g., catalytic filtration) or consume salts and produce spent brine which pollutes the environment (i.e., ion exchange resins). Therefore, it is of prime importance to design a simple and compact, yet robust, system for Mn and Fe control of the domestic GW sources, which can reliably guarantee the desired Mn limit in the finished water ( 20 μ g/L). In the course of this study, we demonstrated, for the first time, that a hybrid hollow fiber nanofiltration (HFNF)-calcite contactor process is a promising alternative for treating domestic GWs with elevated levels of Mn, Fe, natural organic matter (NOM) and hardness. The efficacy of the HFNF membranes in terms of removal of Mn, Fe and NOM and fouling was compared with commercially available NF270 and NF90 membranes. The results revealed that HFNF (100-200 Da) and NF90 maintained considerably high rejection of Mn, Fe and NOM due to their dominant sieving effect. In contrary, the rejections of the above-mentioned components were decreased in the presence of high hardness for the looser HFNF (200-300 Da) and NF270 membranes. No membrane fouling was detected and the permeate flux was stable when the hard GW was filtered with the HFNF membranes, regardless of their molecular weight cut-off and transmembrane pressure, while the permeability of the NF270 and NF90 membranes steadily decline during the filtration. Integrating a calcite contactor, as a post filtration step, to the HFNF process yielded further Mn, Fe and NOM removals from the HFNF permeate and adjustment of its hardness level. The best performance was achieved when a blend of Calcite-CorosexTM ( 90 / 10 wt . % ) was used as a post-treatment to the tight HFNF (100-200 Da).
地下水是全球主要的饮用水源之一。然而，存在不良化合物，特别是锰（Mn）和铁（Fe）（主要共存于地下水中），由于健康和美观问题，被视为饮用水中的有害成分。因此，由家用井供水的个别住宅尤其受到这些问题的威胁。目前的家庭处理技术操作复杂，如果维护不当（如催化过滤）甚至危险，或者消耗盐并产生污染环境的废盐水（即离子交换树脂）。因此，设计一种简单、紧凑且坚固的系统来控制家庭地下水源中的锰和铁至关重要，该系统能够可靠地保证成品水中所需的锰限量（20μg/L）。在本研究过程中，我们首次证明，混合中空纤维纳滤（HFNF）-方解石接触器工艺是处理锰、铁、天然有机物（NOM）和硬度含量较高的家庭地下水的一种有前景的替代方法。将HFNF膜在去除锰、铁和NOM以及抗污染方面的效果与市售的NF270和NF90膜进行了比较。结果表明，HFNF（100 - 200Da）和NF90由于其主要的筛分作用，对锰、铁和NOM保持了相当高的截留率。相反，对于孔径较大的HFNF（200 - 300Da）和NF270膜，在高硬度存在的情况下，上述成分的截留率降低。当用HFNF膜过滤硬地下水时，无论其截留分子量和跨膜压力如何，均未检测到膜污染，渗透通量稳定，而NF270和NF90膜的渗透率在过滤过程中稳步下降。在HFNF工艺中加入方解石接触器作为过滤后步骤，可进一步去除HFNF渗透液中的锰、铁和NOM，并调节其硬度水平。当使用方解石 - CorosexTM（90/10重量%）混合物作为致密HFNF（100 - 200Da）的后处理时，可实现最佳性能。
