Delft University of Technology, Department of Water Management, Stevinweg 1, 2628CN, Delft, the Netherlands.
Delft University of Technology, Department of Water Management, Stevinweg 1, 2628CN, Delft, the Netherlands.
Water Res. 2020 Jul 15;179:115894. doi: 10.1016/j.watres.2020.115894. Epub 2020 May 3.
In drinking water treatment, natural organic matter (NOM) is effectively removed from surface water using ion exchange (IEX). A main drawback of using IEX for NOM removal is the production of spent IEX regeneration brine, a polluting waste that is expensive to discharge. In this work, we studied ceramic nanofiltration as a treatment for the spent NOM-rich brine, with the aim to reduce the volume of this waste and to recycle salt. Compared to polymeric nanofiltration, the fouling was limited. When NOM is rejected and concentrated, a clean permeate with the regeneration salt (NaCl) could be produced and reused in the IEX regeneration process. Bench scale studies revealed that NOM could be effectively separated from the NaCl solution by steric effects. However, the separation of NaCl from other salts present in the brine, such as NaSO, was not sufficient for reuse purposes. The low sulphate rejection was mainly due to the low zeta potential of the membrane at the high ionic strength of the brine. The permeate of the ceramic nanofiltration should be treated further to obtain a sodium chloride quality that can be recycled as a regenerant solution for ion exchange. Further treatment steps will benefit from the removal of NOM from the brine.
在饮用水处理中，离子交换（IEX）可有效去除地表水中的天然有机物（NOM）。使用 IEX 去除 NOM 的一个主要缺点是产生了富含 NOM 的废 IEX 再生盐水，这种污染性废物的排放成本很高。在这项工作中，我们研究了陶瓷纳滤作为处理富含 NOM 的废盐水的方法，目的是减少这种废物的体积并回收盐分。与聚合物纳滤相比，污染有限。当 NOM 被截留和浓缩时，可以生产出清洁的渗透物和再生盐（NaCl），并可在 IEX 再生过程中重复使用。中试研究表明，通过空间位阻作用可以有效地将 NOM 与 NaCl 溶液分离。然而，要将 NaCl 与废水中存在的其他盐（如 NaSO）分离，以达到再利用的目的，效果还不够理想。低硫酸盐截留率主要是由于盐水的高离子强度导致膜的zeta 电位较低。陶瓷纳滤的渗透物需要进一步处理，以获得可作为离子交换再生剂溶液回收的氯化钠质量。进一步的处理步骤将受益于从盐水中去除 NOM。
