Maeda Yasushi
LG Chem Japan Co., Ltd., Kyobashi Trust Tower 12F, 2-1-3 Kyobashi Chuo-ku, Tokyo 104-0031, Japan.
Membranes (Basel). 2022 Jan 31;12(2):170. doi: 10.3390/membranes12020170.
More than 60 years have passed since UCLA first announced the development of an innovative asymmetric cellulose acetate reverse osmosis (RO) membrane in 1960. This innovation opened a gate to use RO for commercial use. RO is now ubiquitous in water treatment and has been used for various applications, including seawater desalination, municipal water treatment, wastewater reuse, ultra-pure water (UPW) production, and industrial process waters, etc. RO is a highly integrated system consisting of a series of unit processes: (1) intake system, (2) pretreatment, (3) RO system, (4) post-treatment, and (5) effluent treatment and discharge system. In each step, a variety of chemicals are used. Among those, sulfites (sodium bisulfite and sodium metabisulfite) have played significant roles in RO, such as dechlorination, preservatives, shock treatment, and sanitization, etc. Sulfites especially became necessary as dechlorinating agents because polyamide hollow-fiber and aromatic thin-film composite RO membranes developed in the late 1960s and 1970s were less tolerable with residual chlorine. In this review, key applications of sulfites are explained in detail. Furthermore, as it is reported that sulfites have some adverse effects on RO membranes and processes, such phenomena will be clarified. In particular, the following two are significant concerns using sulfites: RO membrane oxidation catalyzed by heavy metals and a trigger of biofouling. This review sheds light on the mechanism of membrane oxidation and triggering biofouling by sulfites. Some countermeasures are also introduced to alleviate such problems.
自1960年加州大学洛杉矶分校首次宣布开发出一种创新的不对称醋酸纤维素反渗透（RO）膜以来，已经过去了60多年。这一创新为RO的商业应用打开了大门。如今，RO在水处理中无处不在，并已用于各种应用，包括海水淡化、市政水处理、废水回用、超纯水（UPW）生产以及工业生产用水等。RO是一个高度集成的系统，由一系列单元过程组成：（1）进水系统，（2）预处理，（3）RO系统，（4）后处理，以及（5）出水处理和排放系统。在每个步骤中，都会使用各种化学物质。其中，亚硫酸盐（亚硫酸氢钠和焦亚硫酸钠）在RO中发挥了重要作用，如脱氯、防腐剂、冲击处理和消毒等。亚硫酸盐作为脱氯剂变得尤为必要，因为20世纪60年代末和70年代开发的聚酰胺中空纤维和芳香族复合RO膜对余氯的耐受性较差。在这篇综述中，将详细解释亚硫酸盐的关键应用。此外，由于据报道亚硫酸盐对RO膜和过程有一些不利影响，此类现象将得到阐明。特别是，使用亚硫酸盐时存在以下两个重大问题：重金属催化的RO膜氧化和生物污染的触发因素。这篇综述揭示了亚硫酸盐导致膜氧化和触发生物污染的机制。还介绍了一些缓解此类问题的对策。
