Abstract Mineral scaling is a key limiting factor for membrane desalination and results in increased operation and maintenance costs. In directly coupled battery-less photovoltaic-powered nanofiltration/reverse osmosis (PV–NF/RO) membrane systems, solar energy fluctuations cause intermittent operation and direct osmotic backwash (OB) spontaneously. This potentially induces a self-cleaning mechanism to mitigate scaling. In this study, the impact of different flux decline/scaling mechanisms (concentration polarization (CP), surface crystallization (SC) and bulk crystallization (BC)), membrane type (BW30 and NF270) and controlled solar irradiance fluctuations on OB cleaning efficiency were investigated to explore the feasibility of OB for scaling (CaSO4 and CaCO3) control. The results showed that OB could restore 30–96% flux and partially remove scaling crystals. OB cleaning was more effective for CP and SC than for BC. High-level solar irradiance before fluctuation and long operating time led to severe scaling, which reduced OB cleaning efficiency. Low-level solar irradiance during fluctuations did not affect the scaling formation, but improved OB cleaning efficiency by strong OB. Those results show that spontaneous OB can act as a natural self-cleaning process in directly coupled PV-membrane systems to control scaling during solar irradiance fluctuations.

中文翻译：

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可再生能源驱动的膜技术：渗透反洗对太阳辐照度波动期间结垢的影响

摘要 矿物结垢是膜脱盐的关键限制因素，会增加运行和维护成本。在直接耦合的无电池光伏供电纳滤/反渗透 (PV-NF/RO) 膜系统中，太阳能波动会自发地导致间歇操作和直接渗透反冲洗 (OB)。这可能会引发一种自清洁机制，以减轻结垢。在本研究中，不同通量下降/缩放机制（浓度极化 (CP)、表面结晶 (SC) 和本体结晶 (BC)）、膜类型（BW30 和 NF270）和受控太阳辐照度波动对 OB 清洁效率的影响为研究探索 OB 用于结垢（CaSO4 和 CaCO3）控制的可行性。结果表明，OB 可以恢复 30-96% 的通量并部分去除结垢晶体。OB 清洁对 CP 和 SC 比对 BC 更有效。波动前的高水平太阳辐照度和较长的运行时间导致严重的结垢，从而降低了OB清洗效率。波动期间的低水平太阳辐照度不影响结垢的形成，但通过强 OB 提高了 OB 清洁效率。这些结果表明，自发 OB 可以作为直接耦合 PV 膜系统中的自然自清洁过程，以控制太阳辐照度波动期间的结垢。波动期间的低水平太阳辐照度不影响结垢的形成，但通过强 OB 提高了 OB 清洁效率。这些结果表明，自发 OB 可以作为直接耦合 PV 膜系统中的自然自清洁过程，以控制太阳辐照度波动期间的结垢。波动期间的低水平太阳辐照度不影响结垢的形成，但通过强 OB 提高了 OB 清洁效率。这些结果表明，自发 OB 可以作为直接耦合 PV 膜系统中的自然自清洁过程，以控制太阳辐照度波动期间的结垢。