This research investigated the effects of extending the holding time of samples for microbial analysis beyond the standard of 24 hours for purposes such as watershed characterization. Experiments were conducted with both sanitary wastewater and stormwater samples. The refrigerated samples (4 8C) were held for up to 9 days before being analyzed for two pathogens (Pseudomonas aeruginosa and Staphylococcus aureus) and five indicator organisms (total coliform, fecal coliform, fecal streptococcus, enterococcus, and Escherichia coli) by membrane filtration. The concentrations (as colony-forming units per 100 mL) were normalized by log 10 transformation and used in subsequent statistical analysis testing for significant differences. The results suggested that the concentrations of microorganisms in water samples analyzed on days 1 and 2 did not vary significantly in 8 of 13 analyses. The results of a field study concluded that the concentration of fecal coliform did not change significantly between 7 hours holding time and greater than 24 hours holding time for fecal coliform. Water Environ. Res., 76, 67 (2004).
Onsite pilot testing was recently completed to confirm performance and design criteria for the 380-ML/d (100-mgd) excess flow high-rate treatment facilities that are being designed for the City of Springfield's wastewater treatment plant. The performance of the compressible media filter pilot demonstrated consistent compliance with all regulatory requirements for CSO treatment and produced average effluent TSS concentrations below 30 mg/L while treating wetweather flows. Furthermore, dose response testing demonstrated that the effluent from the compressible media filter was consistently amenable to hypochlorite disinfection, requiring doses and contact times equivalent to those typically used for conventional secondary effluents. The new high-rate treatment facilities will consist of new structures and equipment for influent excess flow interception, screening, compressible media filtration, hypochlorite disinfection, bisulfite dechlorination and effluent pumping. Construction of these upgrades is scheduled to be completed in 2014.
The aim of the Columbus program was to implement a comprehensive watershed monitoring-network including water chemistry, aquatic biology and alternative sensors to establish water environment health and methods for determining future restoration progress and early warning for protection of drinking water supplies. The program was implemented to comply with USA regulatory requirements including Total Maximum Daily Load (TMDL) rules of the Clean Water Act (CWA) and Source Water Assessment and Protection (SWAP) rules under the Safe Drinking Water Act (SDWA). The USEPA Office of Research and Development and the Water Environment Research Foundation provided quality assurance oversight. The results obtained demonstrated that significant wet weather data is necessary to establish relationships between land use, water chemistry, aquatic biology and sensor data. These measurements and relationships formed the basis for calibrating the US EPA BASINS Model, prioritizing watershed health and determination of compliance with water quality standards. Conclusions specify priorities of cost-effective drainage system controls that attenuate stormwater flows and capture flushed pollutants. A network of permanent long-term real-time monitoring using combination of continuous sensor measurements, water column sampling and aquatic biology surveys and a regional organization is prescribed to protect drinking water supplies and measure progress towards water quality targets.
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