亚利桑那州菲尼克斯市的一个主要问题是要求对水处理厂进行改造，以达到降低的三卤甲烷标准。一位顾问设计了一系列可以实施的流程修改和/或变更。对现有工艺操作和额外工艺装置所需的修改取决于EPA设定的最终标准和城市理念。也就是说，是使用除氯以外的消毒剂，还是增加消毒副产品前体材料的去除。该市提出了一些建议，比如安装硫酸进料设备以降低pH值，从而提高天然有机物的去除率，并消除预氯化的做法。该市将重点放在减少三卤甲烷的活动矩阵上，这些活动将成为标准操作实践。这些措施包括强化前体去除，如用硫酸调节pH值以提高明矾凝固的有效性，使用替代混凝剂，如三氯化铁和聚合物，使用粉末活性炭和生物活性炭- 有源滤波器。此外，还对每个处理厂进行了审查，以确定工艺能力和灵活性。对每个工厂的CT值进行评估，以确定处理过程中的最后一点，在该点可以添加氯，并且仍然满足SWTR的要求。保持微生物质量至关重要。

One of the major concerns for the City of Phoenix, Arizona, was required water treatment plant modifications to meet a reduced trihalomethane standard. A consultant devised a series of process modifications and/or changes that could be implemented. The required modifications to existing process operations and additional process units depends upon the final standard set by EPA and the philosophy of the city. That is, whether to use a disinfectant other than chlorine or increase the removal of disinfection byproduct precursor material. The City moved ahead with some recommendations such as installing sulfuric acid feed equipment to depress the pH in order to enhance natural organic matter removal and to eliminate the practice of pre- chlorination. The City focused on a matrix of activities to reduce THMs that would then become standard operational practices. These included enhanced precursors removal such as pH adjustment with sulfuric acid to increase the effectiveness of alum coagulation, the use of alternate coagulants, such as ferric chloride and polymer, the use of powdered activated carbon and biologically-active filters. In addition, each treatment plant was reviewed to determine process capabilities and flexibility. CT values were evaluated for each plant to determine the last point in the treatment process where chlorine could be added and still meet the requirements of the SWTR. The maintenance of microbiological quality was of prime importance.