Department of Environmental Engineering, Gebze Technical University, Çayırova 41400, Kocaeli, Turkey E-mail:
TUBITAK Marmara Research Center, Environment and Cleaner Production Institute, Gebze 41470, Kocaeli, Turkey.
Water Sci Technol. 2021 Nov;84(9):2457-2471. doi: 10.2166/wst.2021.439.
Reverse osmosis concentrate (ROC) is one of the major drawbacks in membrane treatment technologies specifically due to the scale-forming ions. It is important to remove these ions from ROC to enhance total water recovery and reuse in the textile industry that is the largest water-consumer and polluter industry. In this work, coagulation/high pH precipitation (CP) integrated with ceramic microfiltration (CMF) was studied as a pre-treatment method followed by nanofiltration (NF) to increase the efficiency of water recovery. To prevent organic fouling, ferric chloride (FeCl) was applied at a concentration of 3 mM, and ceramic membranes were used for the removal of non-precipitating crystals and/or suspended solids (at high pH) before the NF processes. The CP-CMF method successfully removed calcium (Ca), magnesium (Mg), silica (SiO), and TOC up to 97, 83, 92, and 87% respectively, which resulted in higher performance of the NF process. Moreover, this method provided higher flux at lower pressure that ultimately increased overall water recovery of the NF process to achieve near-zero liquid discharge (n-ZLD). A cost-benefit estimation showed that a high-quality effluent (COD<5 mg/L; conductivity 700<μS/cm; negligible residual color) can be generated and recycled in the textile industry at an economical cost (approximately 0.97 USD/m). Therefore, ROC minimization and water recovery can help to achieve n-ZLD using the CP-CMF/NF method.
反渗透浓缩水（ROC）是膜处理技术的主要缺点之一，特别是由于形成结垢的离子。去除 ROC 中的这些离子对于提高纺织工业的总水回收率和再利用非常重要，因为纺织工业是最大的耗水和污染工业。在这项工作中，混凝/高 pH 沉淀（CP）与陶瓷微滤（CMF）集成作为预处理方法，然后进行纳滤（NF），以提高水回收率。为了防止有机结垢，应用了浓度为 3mM 的三氯化铁（FeCl），并且在 NF 过程之前，使用陶瓷膜去除非沉淀晶体和/或悬浮固体（在高 pH 下）。CP-CMF 方法成功去除了钙（Ca）、镁（Mg）、硅（SiO）和总有机碳（TOC），去除率分别高达 97%、83%、92%和 87%，这使得 NF 过程的性能更高。此外，该方法在较低压力下提供更高的通量，最终提高了 NF 过程的整体水回收率，实现近零液体排放（n-ZLD）。成本效益评估表明，可以以经济的成本（约 0.97 美元/立方米）在纺织工业中生成和回收高质量的出水（COD<5mg/L；电导率 700<μS/cm；几乎没有残留颜色）。因此，使用 CP-CMF/NF 方法可以通过减少 ROC 和提高水回收率来实现 n-ZLD。
