National Institute of Clean-and-Low-Carbon Energy, Chuanghua Road, Changping district, Beijing 102211, China E-mail:
Water Sci Technol. 2022 Feb;85(3):862-871. doi: 10.2166/wst.2022.011.
In order to reduce the cost of chemical softening, the seeded precipitation assisted nanofiltration (NF) process was introduced into zero liquid discharge (ZLD) of flue-gas desulfurization (FGD) wastewater treatment. A pilot-scale system was developed and run for 168 h in a coal-fired power plant. The system mainly consists of lime softening, ambient temperature crystallizer (ATC) and NF, in which the raw water treatment capacity was 1 m/h. The results indicated that the system operated stably, the softening cost was 13.30 RMB/m, and the electricity cost was 3.39 RMB/m for the FGD wastewater in this pilot system. High quality gypsum was got from the ATC unit, of which the purity was 95.8%. Through this system, the hardness removal rate was higher than 98.9% and the water recovery rate reached 96%. In addition, the pressure and permeate flux kept stable in the ultrafiltration (UF) unit and NF unit, indicating no scaling occurred in the two units during 168 h test. Thus, a feasible and cost-effective process was provided by using the seeded precipitation assisted NF to deal with the FGD wastewater.
为降低化学软化成本，将种晶沉淀辅助纳滤（NF）工艺引入烟气脱硫（FGD）废水零排放（ZLD）中。在燃煤电厂中开发并运行了一个中试规模的系统，持续了 168 小时。该系统主要由石灰软化、常温结晶器（ATC）和 NF 组成，原水的处理能力为 1 立方米/小时。结果表明，该系统运行稳定，FGD 废水的软化成本为 13.30 元/立方米，电耗为 3.39 元/立方米。从 ATC 单元获得了高纯度（95.8%）的石膏。通过该系统，硬度去除率高于 98.9%，水回收率达到 96%。此外，在超滤（UF）单元和 NF 单元中，压力和渗透通量保持稳定，表明在 168 小时的测试过程中这两个单元没有结垢。因此，使用种晶沉淀辅助 NF 处理 FGD 废水提供了一种可行且具有成本效益的工艺。
