Systems and methods for quaternary ammonium hydroxide treatment or recovery

This specification describes systems and methods for removing quaternary ammonium hydroxides (e.g., tetramethylammonium hydroxide (TMAH)) from wastewater. The systems and methods can be located at the site of electronic manufacturing and produce a TMAH solution for reuse. The system includes a membrane filtration unit, an ion exchange unit, and an electrodialysis unit (e.g., a three-chamber electrodialysis unit). The method includes filtering the wastewater to preferentially remove contaminants other than quaternary ammonium hydroxides. The filtered water is treated by ion exchange to produce a regenerated stream having an increased concentration of quaternary ammonium cations. The regeneration stream is treated by electrodialysis to form a quaternary ammonium hydroxide solution. 本说明书描述用于从废水中去除季铵氢氧化物(例如四甲基氢氧化铵(TMAH))的系统和方法。所述系统和方法可以位于电子制造的现场，并生产TMAH溶液用于再利用。所述系统包括膜过滤单元、离子交换单元和电渗析单元(例如三室电渗析单元)。所述方法包括过滤废水以优先去除季铵氢氧化物以外的污染物。通过离子交换处理过滤的水，以生产具有增加浓度的季铵阳离子的再生流。通过电渗析处理再生流以形成季铵氢氧化物溶液。