Examination of Reactivation of Fecal Coliforms in Centriguge Dewatered, Anaerobically Digested Sludges

In a recent study of anaerobically digested solids from seven wastewater treatment facilities, counts of fecal coliform bacteria increased after dewatering at four of the facilities tested. Immediately after centrifugation, fecal coliform counts increased from very low or nondetectable levels, often by as much as several orders of magnitude, at the four facilities where increases were observed. This study only looked at seven facilities using anaerobic digestion and high-solids centrifugation for dewatering; numerous other stabilization and dewatering processes are also widely used. The study identifies some potential control methods and mitigation strategies that utilities could use to reduce coliform levels. Developing specific information on mechanisms for reactivation and regrowth, as well as control methods and operational changes, is the focus of further research which is underway. This report comes with a Fact Sheet. 72 pages. Soft cover plus Fact Sheet.

Originally funded as WERF project 03-CTS-13T.