AWWA WQTC69411

This powerpoint presentation begins by providing a brief overview of reuse of treated wastewater in America. Reclaimed wastewater is an increasingly important source of supply; however, there is growing concern about quality at the point-of-use related to the impact of organic matter and regrowth. The objectives of this study were to: identify drivers of microbial growth and degradation in reclaimed water; and, conduct a Disinfection Pipe Loop Study to examine the effects of 2 disinfectants on bulk and biofilm related organisms. The experimental design and methods for this study included the following: four seasons, four consecutive days, from five points for >30 parameters = 2,400 data points; genetically modified AOC test organisms; rapid AOC test; AOC Luminescence Method Standard Curves; and, AOC - Modeling Microbial Growth. Pipeloop disinfection study results indicate the following: planktonic bacteria could be inactivated but biofilm bacteria persisted; higher biofilm and microbial levels occurred at the ends of the system; AOC and BDOC levels increased by free chlorine and somewhat by chloramines; and, the stability of chloramines could be beneficial in reclaimed systems. Study conclusions indicate the following: the rapid bioluminescence method for AOC was successful for measuring the biostability of reclaimed waters; the levels of natural organic matter had a dramatic impact on the microbiology of reclaimed water; AOC levels were about 10 times higher than in drinking water; membrane bioreactors effectively reduce AOC and BDOC levels; conventional treatment effectively removes microbes in wastewater, but regrowth occurred in distribution systems; growth of Legionella and Mycobacterium could have public health significance; and, chloramines could be beneficial in reclaimed systems. Includes tables, figures.