Water and Environmental Engineering, Graduate School of Engineering, Nagasaki University, 1-14 Bunkyo-machi, Nagasaki 852-8521, Japan.
Research & Development Department, Orange County Water District, 18700 Ward Street, Fountain Valley, CA 92708, USA.
Water Res. 2018 Mar 15;131:45-51. doi: 10.1016/j.watres.2017.12.025. Epub 2017 Dec 12.
Direct potable reuse is becoming a feasible option to cope with water shortages. It requires more stringent water quality assurance than indirect potable reuse. Thus, the development of a high-rejection reverse osmosis (RO) membrane for the removal of one of the most challenging chemicals in potable reuse - N-nitrosodimethylamine (NDMA) - ensures further system confidence in reclaimed water quality. This study aimed to achieve over 90% removal of NDMA by modifying three commercial and one prototype RO membrane using heat treatment. Application of heat treatment to a prototype membrane resulted in a record high removal of 92% (1.1-log) of NDMA. Heat treatment reduced conductivity rejection and permeability, while secondary amines, selected as N-nitrosamine precursors, were still well rejected (>98%) regardless of RO membrane type. This study also demonstrated the highly stable separation performance of the heat-treated prototype membrane under conditions of varying feed temperature and permeate flux. Fouling propensity of the prototype membrane was lower than a commercial RO membrane. This study identified a need to develop highly selective RO membranes with high permeability to ensure the feasibility of using these membranes at full scale.
直接饮用水再利用正成为应对水资源短缺的一种可行选择。它比间接饮用水再利用需要更严格的水质保证。因此，开发一种高去除率的反渗透（RO）膜来去除饮用水再利用中最具挑战性的化学物质之一——亚硝二甲胺（NDMA），可确保再回收水中的水质具有更高的可信度。本研究旨在通过对三种商业 RO 膜和一种原型 RO 膜进行热处理，实现对 NDMA 的去除率超过 90%。对原型膜进行热处理，实现了 NDMA 的去除率高达 92%（1.1 对数）的创纪录水平。热处理降低了电导率的去除率和渗透率，而被选为亚硝胺前体的仲胺，无论 RO 膜类型如何，仍被很好地截留（>98%）。本研究还证明了在不同进料温度和渗透通量条件下，经热处理的原型膜具有高度稳定的分离性能。原型膜的污染倾向低于商业 RO 膜。本研究表明需要开发高选择性和高渗透性的 RO 膜，以确保这些膜在大规模应用中的可行性。
