Institute of Environmental Engineering (ISA) RWTH Aachen University, Mies-van-der-Rohe-Str. 1, 52072, Aachen, Germany.
Dow Olefinverbund GmbH, Olefinstraße 1, 04564, Böhlen, Germany.
J Environ Manage. 2024 Sep;367:121949. doi: 10.1016/j.jenvman.2024.121949. Epub 2024 Jul 30.
When water supply restrictions increasingly escalate to water supply risks, developing strategies to minimize the water footprint of wet cooling systems becomes crucial. This study compares two water engineering approaches to minimize the water footprint of a recirculating evaporative cooling tower (CT): (1) reusing cooling tower blowdown and (2) producing demineralized water to increase the cycles of concentration (CoC) of the CT. Our techno-economic analysis across various scenarios and CT settings reveals that reusing blowdown (option 1) is the most feasible approach for an industrial cooling system currently operating at CoCs of > 3, discharging blowdown with a conductivity of 2 mS/cm and a total organic carbon (TOC) concentration of approximately 20 mg/L. Compared to enhanced make up treatment, blowdown reuse allows higher water savings (13 %) and involves lower implementation and operation costs. Pilot scale trials validated the feasibility of both approaches. Blowdown and enhanced make up treatment included biologically activated carbon filtration, ultrafiltration and reverse osmosis, producing high-quality permeate, suitable for (re)use as CT make up or within other processes. The blowdown treatment reached a product quality of 80 μS/cm conductivity and 70 μg/L TOC, make up treatment 20 μS/cm in conductivity and 60 μg/L TOC, respectively. The study's findings underscore the viability of blowdown reuse as a cost-effective and efficient strategy to minimize the water footprint of cooling systems under increasing water scarcity conditions.
当水资源供应限制逐渐升级为水资源供应风险时，制定策略以最小化湿冷却系统的水足迹变得至关重要。本研究比较了两种水工程方法，以最小化循环蒸发冷却塔（CT）的水足迹：（1）再利用冷却塔排污和（2）生产去矿物质水以增加 CT 的浓缩倍数（CoC）。我们在各种情景和 CT 设置下进行的技术经济分析表明，对于目前运行 CoC>3、排放电导率为 2 mS/cm 和总有机碳（TOC）浓度约为 20 mg/L 的冷却塔排污的工业冷却系统，再利用排污（选项 1）是最可行的方法。与强化补给水处理相比，排污再利用可实现更高的节水率（13%），且实施和运营成本更低。中试试验验证了这两种方法的可行性。排污和强化补给水处理均包括生物活性炭过滤、超滤和反渗透，可生产高质量的渗透物，适用于（再）用作 CT 补给水或其他工艺用水。排污处理达到 80 μS/cm 电导率和 70 μg/L TOC 的产品质量，补给水处理达到 20 μS/cm 电导率和 60 μg/L TOC 的产品质量。研究结果强调了在水资源日益短缺的情况下，再利用排污作为一种具有成本效益和高效的策略来最小化冷却系统水足迹的可行性。
