Stricter environmental regulation policies and freshwater as an increasingly valuable resource have led to global growth of zero liquid discharge (ZLD) processes in recent years. During this development, in addition to water, the recovery of recyclable materials, e.g. salts, from industrial wastewater and brines is considered more frequently. Within the framework of the HighCon research project, the subject of this study, a new ZLD process with the goal of pure single-salt recovery from industrial wastewater has been developed and investigated in a demonstrational setup at an industrial site. With regard to pure salts recovery, separating organic components is of great importance during the treatment of the concentrate arising from used water recycling. The removal of COD and of ions responsible for scaling worked very well using nanofiltration. The nanofiltration permeate containing the monovalent ions was pre-concentrated using electrodialysis and membrane distillation before selective crystallization for single-salt recovery was performed. An example economic case study for the newly developed ZLD process – based on demonstration results and considering optimization measures for a full-scale design – indicates that the costs are equal to those of a conventional ZLD process, which, however, does not provide inter alia the aforementioned benefit of single-salt recovery.

近年来，更严格的环境法规政策和淡水已成为越来越有价值的资源，导致全球零液体排放（ZLD）工艺的发展。在此开发过程中，除水外，人们还更频繁地考虑从工业废水和盐水中回收可循环利用的材料（例如盐）。在HighCon研究项目的框架内，本研究的主题是开发一种新的ZLD工艺，其目的是从工业废水中回收纯单盐，并在工业现场进行了示范性研究。关于纯盐的回收，在处理由废水循环产生的精矿过程中，分离有机成分非常重要。使用纳滤可以很好地去除COD和负责结垢的离子。使用电渗析和膜蒸馏对含有单价离子的纳滤渗透物进行预浓缩，然后进行选择性结晶以回收单盐。针对新开发的ZLD工艺的经济案例研究（基于演示结果并考虑了全尺寸设计的优化措施）表明，成本与常规ZLD工艺的成本相同，但是并不能提供尤其是上述单盐回收的好处。