Efficient desalination through a reverse osmosis (RO) membrane requires the prior removal of blockade-causing substances from raw seawater. To achieve ultrahigh-speed processing of a pretreatment process for seawater RO desalination, we combine traditional softening with ballasted flocculation (SBF) for Ca²⁺ and Mg²⁺ removal. An alkaline mixture of Ca(OH)₂ and Na₂CO₃ was the most suitable softening agent for Ca²⁺ and Mg²⁺ removal with a reduced amount of generated sludge. This softening treatment simultaneously removed the suspended solids and bacteria from actual seawater. The settling velocity of the suspended solids generated via seawater softening was extremely low. Under the optimum conditions for desalinating actual seawater using an anionic polymer flocculant and microsand, the settling velocity exceeded 3.5 cm/s, 833 times higher than that of softening without ballasted flocculation. The amount of sludge after standing for 3 min was 76.5% lower in SBF than in conventional softening. The silt density index of the treated seawater met the water-supply standard of RO membranes (i.e., <3.0). Furthermore, the SBF-generated sludge exhibited considerably improved dewatering property than the sludge obtained via conventional softening. SBF can efficiently and quickly remove the causative substances of RO membrane fouling from seawater, thereby improving the treatability of generated sludge. SBF provides a new pretreatment process for seawater desalination using RO membranes.

通过反渗透 (RO) 膜进行高效脱盐需要事先从原海水中去除引起阻塞的物质。为了实现海水反渗透脱盐预处理工艺的超高速处理，我们将传统软化与压载絮凝 (SBF) 相结合，以去除Ca ²⁺和 Mg ^{2+ 。}_{Ca(OH) 2}和Na ₂ CO ₃的碱性混合物是最适合Ca ²⁺和Mg ²⁺的软化剂以减少产生的污泥量去除。这种软化处理同时去除了实际海水中的悬浮物和细菌。海水软化产生的悬浮物沉降速度极低。在使用阴离子聚合物絮凝剂和微砂对实际海水进行淡化的最佳条件下，沉降速度超过3.5 cm/s，是无压载絮凝软化速度的833倍。SBF 静置 3 分钟后的污泥量比常规软化低 76.5%。处理后的海水含沙量指标达到反渗透膜的供水标准（即<3.0）。此外，与通过常规软化获得的污泥相比，SBF 产生的污泥具有显着改善的脱水性能。SBF能高效快速地去除海水中RO膜污染的致病物质，从而提高产生污泥的可处理性。SBF为使用反渗透膜的海水淡化提供了一种新的预处理工艺。