Hagglund Christopher R, Duranceau Steven J
Department of Civil, Environmental and Construction Engineering, University of Central Florida, 4000 Central Florida Blvd., Orlando, FL 32816-2450, USA.
Membranes (Basel). 2024 Jul 24;14(8):164. doi: 10.3390/membranes14080164.
A two-stage pilot plant study has been completed that evaluated the performance of a reverse osmosis (RO) membrane process for the treatment of feedwater that consisted of a blend of a nanofiltration (NF) concentrate and brackish groundwater. Membrane performance was assessed by monitoring the process operation, collecting water quality data, and documenting the blended feedwater's impact on fouling due to microbiological or organic means, plugging, and scaling, or their combination. Fluorescence and biological activity reaction tests were used to identify the types of organics and microorganisms present in the blended feedwater. Additionally, scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) were used to analyze suspended matter that collected on the surfaces of cartridge filters used in the pilot's pretreatment system. SEM and EDS were also used to evaluate solids collected on the surfaces of 0.45 µm silver filter pads after filtering known volumes of NF concentrate and RO feedwater blends. Water quality analyses confirmed that the blended feedwater contained little to no dissolved oxygen, and a significant amount of particulate matter was absent from the blended feedwater as defined by silt density index and turbidity measurements. However, water quality results suggested that the presence of sulfate, sulfide, iron, anaerobic bacteria, and humic acid organics likely contributed to the formation of pyrite observed on some of the membrane surfaces autopsied at the conclusion of pilot operations. It was determined that first-stage membrane productivity was impacted by the location of cartridge filter pretreatment; however, second-stage productivity was maintained with no observed flux decline during the entire pilot operation's timeline. Study results indicated that the operation of an RO process treating a blend of an NF concentrate and brackish groundwater could maintain a sustainable and productive operation that provided a practical minimum liquid discharge process operation for the NF concentrate, while the dilution of RO feedwater salinity would lower overall production costs.
已完成一项两阶段中试工厂研究，该研究评估了反渗透（RO）膜工艺处理由纳滤（NF）浓缩液和微咸地下水混合而成的给水的性能。通过监测工艺运行、收集水质数据以及记录混合给水对微生物或有机物导致的污垢、堵塞、结垢或其组合的影响，来评估膜性能。使用荧光和生物活性反应测试来识别混合给水中存在的有机物和微生物类型。此外，使用扫描电子显微镜（SEM）和能量色散X射线光谱（EDS）来分析中试预处理系统中使用的筒式过滤器表面收集的悬浮物。SEM和EDS还用于评估在过滤已知体积的NF浓缩液和RO给水混合物后，收集在0.45 µm银滤垫表面的固体。水质分析证实，混合给水中几乎没有溶解氧，并且根据淤泥密度指数和浊度测量，混合给水中不存在大量颗粒物。然而，水质结果表明，硫酸盐、硫化物、铁、厌氧细菌和腐殖酸有机物的存在可能导致了在中试操作结束时对一些膜表面进行尸检时观察到的黄铁矿的形成。已确定第一阶段膜的生产率受筒式过滤器预处理位置的影响；然而，在整个中试操作期间，第二阶段的生产率得以维持，未观察到通量下降。研究结果表明，运行RO工艺处理NF浓缩液和微咸地下水的混合物可以维持可持续且高效的运行，为NF浓缩液提供了一种切实可行的最小液体排放工艺操作，同时RO给水盐度的稀释将降低总体生产成本。
