自弗吉尼亚州纽波特纽斯市1982年为了控制三卤甲烷而在其水处理设施中取消预氯化以来，人工清洗沉淀池中明矾污泥的恶化以及沉淀水质的偶尔下降一直困扰着该市。实验室和现场研究表明，人工清洗的沉淀池（但机械清洗的沉淀池）中的厌氧条件发展迅速，使锰从污泥中释放到上覆水中。研究发现，使用二氧化氯作为预氧化剂可以抑制锰的释放，产生具有改善脱水特性的污泥，并延长过滤器运行时间。包括1个参考，数字。

Ever since the city of Newport News, Virginia, eliminated prechlorination at its water treatment facilities in 1982 in order to control trihalomethanes, it has been plagued by deterioration of alum sludges in manually cleaned sedimentation basins and by occasional declines in settled water quality. Laboratory and field studies showed that anaerobic conditions develop rapidly in manually cleaned sedimentation basins (but not in those that are mechanically cleaned), allowing manganese to be released from the sludge into the overlying water. The use of chlorine dioxide as a preoxidant was found to suppress this release of manganese, produce sludges with improved dewatering characteristics, and lengthen filter runs. Includes 1 reference, figures.