Graduate School of Engineering, Nagasaki University, 1-14 Bunkyo-machi, Nagasaki, 852-8521, Japan.
Graduate School of Science and Engineering, Kagoshima University, 1-21-24 Korimoto, Kagoshima, 890-0065, Japan.
Chemosphere. 2022 Feb;288(Pt 3):132610. doi: 10.1016/j.chemosphere.2021.132610. Epub 2021 Oct 19.
Achieving high water recovery using reverse osmosis membranes is challenging during water recycling because the increased concentrations of organics and inorganics in wastewater can cause rapid membrane fouling, necessitating frequent cleaning using chemical agents. This study evaluated the potential of membrane distillation to purify reverse osmosis-concentrated wastewater and achieve 98% overall water recovery for potable water reuse. The results indicate that membrane fouling during membrane distillation treatment was low (4% reduction in permeability) until 98% water recovery. In contrast, membrane fouling during reverse osmosis treatments was high (73% reduction in permeability) before reaching 90% water recovery. Furthermore, membrane distillation showed superior performance in removing dissolved ions (99.9%) from wastewater as compared with reverse osmosis (98.9%). However, although membrane distillation removed most trace organic chemicals tested in this study, a negligible rejection (11%) was observed for N-nitrosodimethylamine, a disinfection byproduct regulated in potable water reuse. In contrast, RO treatment exhibited a high removal of N-nitrosodimethylamine (70%). Post-treatment (e.g., advanced oxidation) after reverse osmosis and membrane distillation may be needed to comply with the N-nitrosodimethylamine regulations. Overall, the membrane distillation process had the capacity to purify reverse osmosis concentrate with insignificant membrane fouling.
采用反渗透膜实现高水回收率在废水循环利用过程中具有挑战性，因为废水中有机物和无机物浓度的增加会导致膜迅速污堵，需要频繁使用化学药剂进行清洗。本研究评估了膜蒸馏净化反渗透浓缩废水并实现 98%饮用水回用总回收率的潜力。结果表明，在膜蒸馏处理过程中膜污染较低（渗透率降低 4%），直到达到 98%的水回收率。相比之下，在反渗透处理过程中，在达到 90%的水回收率之前，膜污染较高（渗透率降低 73%）。此外，膜蒸馏在去除废水中溶解离子（99.9%）方面的性能优于反渗透（98.9%）。然而，尽管膜蒸馏去除了本研究中测试的大多数痕量有机化学品，但对饮用水回用中受监管的消毒副产物 N-亚硝基二甲胺的去除率仅为 11%。相比之下，RO 处理对 N-亚硝基二甲胺的去除率高达 70%。反渗透和膜蒸馏后处理（例如，高级氧化）可能需要符合 N-亚硝基二甲胺法规。总体而言，膜蒸馏过程具有净化反渗透浓缩物而不会造成显著膜污染的能力。
