AWWA JAW59343

The need to recycle water is a growing issue in water-poor areas of the United States and around the world. However, certain pathogens, such as Cryptosporidium, can be present in recycled water and pose a danger to human health. This article describes a recent project that was conducted to explore efficient ways to eliminate the threat posed by Cryptosporidium in microfiltration residuals. After reviewing the various methods to treat microfiltration residuals, the authors focused their research on clarification for several reasons that include: clarification was successful in treating spent filter backwash water from conventional wastewater treatment plants; clarification was economical; and, clarification was familiar to U.S. plant operators and regulators. Includes 16 references, tables, figures.