Closed-circuit reverse osmosis (CCRO) was piloted to treat RO concentrate from a potable reuse facility to increase the RO recovery beyond 85%. The study determined optimum operating conditions and maintenance requirements for sustained performance at maximum recovery including flux, cross-flow velocity, and membrane cleaning intervals. The CCRO pilot included a “side conduit” to displace spent concentrate without depressurizing the membrane elements. Performance was evaluated in terms of recovery, clean-in-place (CIP) frequency, and permeate quality. Adaptive control strategies were implemented to manage feed water quality fluctuations by operating in variable recoveries where cycle-to-cycle recovery was controlled by concentrate conductivity, feed pressure and volumetric recovery. An important contribution of this study is the long-term pilot dataset collected over two years of operation, which showed the treatment of RO concentrate by CCRO to be technically feasible and operationally sustainable. The pilot operated continuously with a CIP interval greater than two months and produced permeate that met potable reuse requirements. At theoretical full scale, CCRO could increase the facility RO recovery from 85% to 91% (92% was demonstrated in a short-term run). At the future expanded plant capacity of 130 million gallons per day (MGD) (5.7 m³/s), this corresponds to a production increase to 139 MGD (6.1 m³/s).

闭路反渗透 (CCRO) 被试用于处理来自饮用水再利用设施的 RO 浓缩物，以将 RO 回收率提高到 85% 以上。该研究确定了在最大回收率下保持性能的最佳操作条件和维护要求，包括通量、错流速度和膜清洁间隔。CCRO 试点包括一个“侧导管”，用于在不降低膜元件压力的情况下置换废浓缩液。根据回收率、原位清洗 (CIP) 频率和渗透质量评估性能。自适应控制策略通过在可变回收率下运行来管理进水水质波动，其中循环到循环的回收率由浓缩物电导率、进水压力和体积回收率控制。本研究的一个重要贡献是收集了超过两年运行的长期试点数据集，表明 CCRO 处理 RO 精矿在技术上可行且在操作上是可持续的。该试点以超过两个月的 CIP 间隔连续运行，并产生满足饮用水再利用要求的渗透物。在理论上，CCRO 可以将设施 RO 回收率从 85% 提高到 91%（在短期运行中证明了 92%）。未来工厂产能将扩大至每天 1.3 亿加仑 (MGD) (5.7 m 在理论上，CCRO 可以将设施 RO 回收率从 85% 提高到 91%（在短期运行中证明了 92%）。未来工厂产能将扩大至每天 1.3 亿加仑 (MGD) (5.7 m 在理论上，CCRO 可以将设施 RO 回收率从 85% 提高到 91%（在短期运行中证明了 92%）。未来工厂产能将扩大至每天 1.3 亿加仑 (MGD) (5.7 m³ /s)，这对应于产量增加到 139 MGD (6.1 m ³ /s)。