Continuous regeneration of industrial pickling solutions and recovery of valuable materials are implemented in a pilot-scale plant including diffusion dialysis (DD), where HCl is recovered, membrane distillation (MD), where HCl is concentrated, and reactive precipitation (CSTR), where metal ions are recovered in different forms. The integration of the three processes allows to minimize waste streams generation and to accomplish a closed-loop process, thus increasing the environmental sustainability and economic impact of the galvanizing industry. Process reliability was proved through the operation of a demonstrator in the real industrial environment of the Tecnozinco SrL hot-dip galvanizing plant (Carini, Italy), assessing the actual performance in fully reducing spent pickling solution disposal and recovering useful compounds. Tests were conducted firstly with synthetic solutions and then with real waste liquors from the pickling plant. A high acid recovery (80%) can be achieved in the diffusion dialysis unit and quantitative metals separation was accomplished, with iron hydroxide produced at 99% purity. The membrane distillation performance suffers when metal salts are present in large quantities, due to the “salting out” effect, resulting in reduced water vapor pressure, though the use of available low grade waste heat allows energy-sustainable operation of the MD.

在一个中试规模的工厂中实现了工业酸洗溶液的连续再生和有价值的材料的回收，其中包括扩散渗析（DD）（其中回收了HCl），膜蒸馏（MD）（其中浓缩了HCl）和反应沉淀（CSTR），其中金属离子以不同的形式回收。这三个过程的集成可以最大程度地减少废物流的产生并完成闭环过程，从而提高镀锌行业的环境可持续性和经济影响。通过在Tecnozinco SrL热浸镀锌厂（意大利卡里尼）的实际工业环境中运行演示器，评估了在充分减少废酸洗液的处理和回收有用化合物方面的实际性能，证明了过程的可靠性。首先使用合成溶液进行测试，然后使用酸洗厂的废液进行测试。在扩散渗析装置中可以实现较高的酸回收率（80％），并完成了定量的金属分离，并以99％的纯度生产了氢氧化铁。当金属盐大量存在时，由于“盐析”效应，膜蒸馏性能会受到影响，从而导致水蒸气压力降低，尽管使用可用的低级余热可以使MD保持能量可持续运行。