Hybrid forward osmosis - Freeze concentration process for process water purification and recovery

化工和采矿业的零液体排放（ZLD）尚未完全实现，淡水摄入量仍然很高。在多伦多大学的水创新研究所，我们最近开发了一种获得专利的混合正渗透（FO）-冷冻浓缩（FC）工艺，用于从受污染的工业废水中回收水。在FO-FC中回收的水可以在工业操作中重复使用，从而最大限度地减少淡水摄入量。在FO中，水自发地渗透通过膜进入浓缩的汲取溶液中。然后冷冻（FC）所得的稀释的驱动溶液以产生冰形式的淡水，留下再生的浓缩的驱动溶液以再循环到工艺中。冷冻水的能量优势比水蒸发少七倍。特别是在加拿大，由于该国的气候，每年有几个月的冷冻能源是免费的，这表明了一种更加节能的绿色技术。该概念的另一个优点是可以自由地使用任何高度可溶且无毒的电解质作为汲取溶质，这可以产生非常高的渗透压梯度，与常规FO技术相比，其能够从受污染的流中汲取3至5倍多的水。推进FO-FC将使加拿大在合理的时间内以节能和经济的方式向ZLD迈进一步。虽然FO-FC工艺在实验室规模上得到了验证，但我们现在建议通过开发与现有正渗透膜系统集成的连续制冰反应器来在微型中试规模上证明上述工艺概念。由此产生的设施将用于在连续运行下展示这一概念，并使这一创新更接近市场。将研究操作变量，如流速、保留时间、电解质类型、冷冻速率和温度、膜类型，以优化连续操作。

Zero liquid discharge (ZLD) in chemical and mining industry operations has not been fully achieved yet and fresh water intakes are still high. At the Institute for Water Innovation of the University of Toronto, we recently developed a patented hybrid Forward Osmosis (FO)-Freeze Concentration (FC) process to recover water from contaminated industrial effluents. The water recovered in FO-FC can be reused in industrial operations, minimizing the fresh water intakes. In FO water permeates spontaneously through a membrane into a concentrated draw solution. The resulting dilute draw solution is then frozen (FC) to produce fresh water as ice, leaving behind the regenerated concentrated draw solution to be recycled into the process. The energy advantage of freezing water is up to seven times less than water evaporation. Particularly in Canada, the energy for freezing is free several months per year, due to the country's climate, suggesting an even more energy free green technology. An added advantage of this concept is the freedom to use any highly soluble and non-toxic electrolyte as the draw solute, which can generate very high osmotic pressure gradients capable of pulling 3 to 5 times more water more water from the contaminated streams compared to conventional FO technology. Advancing FO-FC will bring Canada one step closer to ZLD in an energy efficient and economical way, within a reasonable period of time. Although the FO-FC process was proven at the lab scale, we now propose to demonstrate the above process concept at a micro pilot scale by developing a continuous ice producing reactor that will be integrated with an existing forward osmosis membrane system. The resulting facility will be used to demonstrate the concept under continuous operation and bring this innovation one step closer to the market. Operating variables such as flow rate, retention time, type of electrolyte, freezing rate and temperature, type of membrane will be investigated to optimize the continuous operation.