Abstract In theory, the batch reverse osmosis (RO) process achieves the lowest practical energy consumption by varying pressure over time. However, few batch RO systems have been built and operated. We have designed, built, and operated the first “true” batch RO prototype using a flexible bladder. The flexible bladder serves as the high-pressure variable-volume tank that is inherent to true batch RO designs (as opposed to batch RO with energy recovery devices). We experimentally validated a model of batch RO energy consumption (≤2.7% difference) by measuring the hydraulic work of the high pressure and circulation pumps. We find that batch RO energy consumption will be greater than expected mostly due to salt retention, a problem neglected by most previous studies. However, despite operating at elevated salinity and flux conditions, batch RO can still save energy relative to single-stage and multi-stage continuous systems. For a seawater desalination plant (35 g/kg intake, 50% recovery, 15 L m−2 h−1), our newly-validated model predicts that batch RO would save 11% energy compared to a single-stage continuous RO plant. Our work demonstrates that batch RO is an energy-efficient process with the potential to reduce the cost of water desalination.

中文翻译：

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盐保留对真正批量反渗透能耗的影响：实验和模型验证

摘要 理论上，间歇式反渗透 (RO) 工艺通过随时间改变压力来实现最低的实际能耗。然而，很少有批量反渗透系统已经建成和运行。我们使用柔性气囊设计、建造和运行了第一个“真正的”批量反渗透原型。柔性气囊用作真正的批量 RO 设计（与带有能量回收装置的批量 RO 相对）所固有的高压可变容积罐。我们通过测量高压泵和循环泵的液压功，通过实验验证了批量 RO 能耗模型（差异≤2.7%）。我们发现批量 RO 能耗将高于预期，主要是由于盐分保留，这是大多数先前研究忽略的问题。然而，尽管在高盐度和通量条件下运行，相对于单级和多级连续系统，批量反渗透仍然可以节省能源。对于海水淡化厂（35 g/kg 摄入量，50% 回收率，15 L m-2 h-1），我们新验证的模型预测，与单级连续 RO 工厂相比，批量 RO 将节省 11% 的能源。我们的工作表明，批量反渗透是一种节能工艺，具有降低海水淡化成本的潜力。