在过去十年里，佛罗里达州众多“坚硬”有色地下水供应的软化处理过程发生了显著变化。在过去市政当局会使用石灰软化的地方，现在正在选择膜软化技术，因为除了软化之外，膜软化技术还能去除颜色和消毒副产品前体。通常，佛罗里达州的地下水供应被归类为“坚硬”；钙含量相对较高的。其中许多还含有大量溶解的有机物、硫化氢和铁。直到大约十年前，佛罗里达州所有进行软化的市政地下水处理厂基本上都使用石灰软化工艺，在许多情况下，使用相对高剂量的氯进行消毒和“漂白”- 脱色。“随着更严格的饮用水标准（尤其是消毒剂和消毒剂副产品）的开始，以及纳滤膜的开发和商业化，该州新的软化厂在处理有色地下水时更倾向于膜软化，而不是石灰软化。根据一项新的膜软化厂成本调查的结果，本文提出佛罗里达州膜软化水处理厂的建设、运行和维护（O&M）以及总处理水成本。

Over the past ten years, there has been a remarkable shift in the treatment process of choice for softening the numerous "hard," colored groundwater supplies in Florida. Where municipalities would have used lime softening in the past, membrane softening technologies now are being selected because of their ability to remove color and disinfection byproduct precursors in addition to softening. Commonly, groundwater supplies in Florida are classified as being "hard"; having relatively high concentrations of calcium. Many of these supplies also have substantial dissolved organic color, hydrogen sulfide, and iron. Until about ten years ago, essentially all municipal groundwater treatment plants in Florida practicing softening used the lime softening process and, in many cases, relatively high dosages of chlorine for disinfection and "bleaching-out color." With the onset of more stringent drinking water standards, particularly for disinfectants and disinfectant byproducts, and the development and commercialization of nanofiltration membranes, new softening plants in the state have favored membrane softening over lime softening in treating colored groundwater. Based on the results of a new membrane softening plant cost survey, this paper presents construction, operation and maintenance (O&M), and total treated water costs of membrane softening water treatment plants in Florida.