Department of Environment, Land and Infrastructure Engineering (DIATI), Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Turin, Italy.
Department of Environment, Land and Infrastructure Engineering (DIATI), Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Turin, Italy.
Environ Int. 2021 Jul;152:106498. doi: 10.1016/j.envint.2021.106498. Epub 2021 Mar 14.
Forward osmosis (FO) is a promising technology for the treatment of complex water and wastewater streams. Studies around FO are focusing on identifying potential applications and on overcoming its technological limitations. Another important aspect to be addressed is the environmental sustainability of FO. With the aim to partially fill this gap, this study presents a life cycle analysis (LCA) of a potential full-scale FO system. From a purely environmental standpoint, results suggest that significantly higher impacts would be associated with the deployment of thermolytic, organic, and fertilizer-based draw solutes, compared to more accessible inorganic compounds. The influent draw osmotic pressure in FO influences the design of the real-scale filtration system and in turn its environmental sustainability. In systems combining FO with a pressure-driven membrane process to recover the draw solute (reverse osmosis or nanofiltration), the environmental sustainability is governed by a trade-off between the energy required by the regeneration step and the draw solution management. With the deployment of environmentally sustainable draw solutes (e.g., NaCl, NaSO), the impacts of the FO-based coupled system are almost completely associated to the energy required to run the downstream recovery step. On the contrary, the management of the draw solution, i.e., its replacement and the required additions due to potential losses during the filtration cycles, plays a dominant role in the environmental burdens associated with FO-based systems exploiting less sustainable draw solute, such as MgCl.
正向渗透（FO）是一种很有前途的处理复杂水和废水的技术。围绕 FO 的研究主要集中在确定潜在的应用和克服其技术限制上。另一个需要解决的重要方面是 FO 的环境可持续性。本研究旨在部分填补这一空白，对潜在的全规模 FO 系统进行了生命周期分析（LCA）。从纯粹的环境角度来看，结果表明，与更易获得的无机化合物相比，热解、有机和基于肥料的汲取剂的部署将带来更高的影响。FO 中的进水汲取渗透压会影响实际规模过滤系统的设计，进而影响其环境可持续性。在将 FO 与压力驱动的膜工艺（反渗透或纳滤）结合以回收汲取剂的系统中，环境可持续性取决于再生步骤所需的能量与汲取液管理之间的权衡。在部署环境可持续的汲取剂（例如 NaCl、NaSO）的情况下，基于 FO 的耦合系统的影响几乎完全与运行下游回收步骤所需的能量有关。相反，汲取液的管理，即其更换以及由于在过滤循环中可能的损失而需要添加，在与利用不太可持续的汲取剂（如 MgCl）的 FO 系统相关的环境负担中起着主导作用。
