Abstract With the growing of electronics, semiconductors, food and pharmaceutical manufactures, the need of water quantity with high purity is increasing. The water quality needed should be with high electrical resistance and free of weakly ionized dissolved species. Integration of separation processes such as reverse osmosis (RO) and electrodeionization (EDI) was proven to be successful to produce water with high quality. This paper is about the applicability of EDI method for post-treatment of RO permeate of geothermal water. For this purpose, the effects of process parameters such as feed flow rate, electrical potential applied, type of ion exchange membranes, and cell number on reduction of electrical conductivity and the contents of boron, silicon and arsenic in EDI product water were investigated. In addition, pseudo first order and pseudo second order kinetics models, infinitive solution volume (ISV) and unreacted core (UCM) models were applied to determine the rate controlling steps of the removal of electrical conductivity and boron by EDI process. Obtained results revealed that a EDI product water containing ˂0.20 mg B/L, ˂0.05 mg Si/L and ˂0.10 μg As/L was produced using a multi-cell EDI in which ion exchange resins in mixed bed configuration is placed between Neosepta CMX-AMX ion exchange membrane pair. These results were obtained when the optimum flow rate of 1.08 L/h and electrical potential of 20 V were applied to multi-cell EDI. At the optimal operational conditions, boron removal was found to be governed by second order kinetic model and the determining steps were film diffusion and liquid film according to ISV and UCM models, respectively. It was observed that thick ion exchange membranes were better than thin ion exchange membranes for polishing RO permeate of geothermal water by using EDI process.

中文翻译：

---

电去离子（EDI）法操作条件对地热水反渗透渗透液后处理的影响

摘要 随着电子、半导体、食品、医药等行业的发展，对高纯度水的需求日益增加。所需的水质应具有高电阻且不含弱电离溶解物质。事实证明，反渗透 (RO) 和电去离子 (EDI) 等分离过程的集成可以成功生产高质量的水。本文探讨了EDI方法在地热水RO渗透后处理中的适用性。为此，研究了进料流速、施加的电势、离子交换膜的类型和电池数量等工艺参数对电导率降低以及 EDI 产品水中硼、硅和砷含量的影响。此外，应用伪一级和伪二级动力学模型、不定溶液体积 (ISV) 和未反应核心 (UCM) 模型来确定 EDI 工艺去除电导率和硼的速率控制步骤。获得的结果表明，使用多池 EDI 生产含有 ˂0.20 mg B/L、˂0.05 mg Si/L 和 ˂0.10 μg As/L 的 EDI 产品水，其中混合床配置的离子交换树脂放置在 Neosepta 之间CMX-AMX 离子交换膜对。这些结果是在将 1.08 L/h 的最佳流速和 20 V 的电位应用于多池 EDI 时获得的。在最佳操作条件下，硼去除受二阶动力学模型控制，决定步骤分别是根据 ISV 和 UCM 模型的膜扩散和液膜。