Minimum Liquid Discharge (MLD) and Zero Liquid Discharge (ZLD) schemes have been widely proposed in the recent scientific literature not only as a possible solution to brine disposal but also as a non-conventional sustainable source of raw materials. Nevertheless, very few works have pushed the idea towards a real demonstration activity, and this somehow limits the reliability that such schemes have with respect to the real implementation potential at the industrial scale. In this work, for the first time in the literature, an integrated treatment chain for the sustainable production of freshwater and minerals has been demonstrated at a pre-industrial scale, in the island of Lampedusa (Italy). The treatment chain included a Nanofiltration (NF) step to separate monovalent and bivalent ions, followed by a Multi-Effect Distillation (MED) unit, powered by waste heat from a Thermal Power plant, generating high-quality water (<30 μS/cm) and an ultra-concentrated brine. The latter was treated in Evaporation Ponds (EPs) to generate high purity NaCl (>99 %). On the other side, the NF retentate was treated to selectively recover magnesium and calcium hydroxides (Mg(OH) purity up to 98 %) in a novel Multiple Feed-Plug Flow Reactor (MF-PFR). The resulting brine fed an ElectroDialysis with Bipolar Membranes unit (EDBM), generating in-situ alkaline and acidic solutions: chemicals needed for internal usage in the plant. All units were successfully tested, reaching satisfactory performance indicators. Furthermore, the stability of each unit during the daily operational run was assessed and successfully achieved, demonstrating not only the technical feasibility of the proposed demo plant, but also the feasibility of MLD as a sustainable alternative for minerals recovery.

中文翻译：

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开创性的最小液体排放海水淡化：兰佩杜萨岛的试点研究

最小液体排放（MLD）和零液体排放（ZLD）方案在最近的科学文献中被广泛提出，不仅作为盐水处理的可能解决方案，而且作为非传统的可持续原材料来源。然而，很少有工作将这一想法推向真正的示范活动，这在某种程度上限制了此类计划在工业规模的实际实施潜力方面的可靠性。在这项工作中，在文献中首次在兰佩杜萨岛（意大利）以工业化前规模展示了用于可持续生产淡水和矿物质的综合处理链。处理链包括纳滤 (NF) 步骤，用于分离单价和二价离子，然后是多效蒸馏 (MED) 装置，由火力发电厂的废热提供动力，产生高质量的水 (<30 μS/cm ）和超浓缩盐水。后者在蒸发池 (EP) 中进行处理，生成高纯度 NaCl (>99%)。另一方面，在新型多进料塞流反应器 (MF-PFR) 中对 NF 渗余物进行处理，选择性回收氢氧化镁和氢氧化钙（Mg(OH) 纯度高达 98%）。产生的盐水供给双极膜电渗析装置 (EDBM)，生成原位碱性和酸性溶液：工厂内部使用所需的化学品。所有机组均已成功测试，达到满意的性能指标。此外，对每个装置在日常运行期间的稳定性进行了评估并成功实现，这不仅证明了拟议示范工厂的技术可行性，而且证明了 MLD 作为矿物回收的可持续替代方案的可行性。