Changes in antibiotic resistance of Escherichia coli in the different stages of conventional domestic wastewater treatment were investigated. Over two years, more than 3500 E. coli isolates from four stages of the wastewater treatment process were tested for resistance to six different antibiotics. The percent resistance of bacteria from any of the stages was highly variable in different samples. Because of this variability, no statistically significant difference was found in the overall percent resistance of E. coli from influent to effluent. When comparing different stages within samples, however, there seemed to be an increase in resistance to ampicillin and amoxicillin between the raw influent and primary effluent. In addition, the percent of isolates with multiple antibiotic resistance, resistant to more than one and less than five antibiotics, and highly multiple antibiotic resistance, resistant to at least five antibiotics, increased through the treatment process. Water Environ. Res., 81, 878 (2009).
The Boston Water and Sewer Commission (the Commission) has conducted a comprehensive assessment of pollutant loadings from its closed conduit and open channel drainage systems to the receiving waters of the Charles River, Neponset River, and Boston Harbor. A uniquely detailed Environmental Protection Agency (EPA) Storm Water Management Model (SWMM) computer model was adapted from an existing system-wide 4,000 node hydraulic model and used to assess sources, loads, and mitigation alternatives for 13 pollutants discharging from the city's drain systems to its receiving waters. The model is calibrated to baseflow and stormwater runoff observed throughout a five-month flow monitoring program, water quality data obtained at 20 sites over six rainstorms and six dry-weather sampling events during the flow monitoring program, and historic data. The model has been used to assess the potential of improved best management practices, green stormwater infrastructure implementation, and low-impact development practices for meeting total maximum daily loads (TMDLs) and water quality standards. The model simulates pollutant buildup and washoff across nine land uses as well as contributions from groundwater, illicit flow, and rainfall. It simulates pollutant conveyance through open and closed conduit systems, first-order decay of oxygen demand, bacteria die-off, bacteria resuspension from sources in sediment bed load and pollutant removal through natural and constructed detention/treatment systems.
The City of Franklin, Tennessee (City) is a fast-growing community with population expected to nearly double within the next 30 years. The City relies on river withdrawals to a small water treatment facility and a regional wholesale provider for drinking water. With the exception of a few individual septic systems, the City collects and treats all of its wastewater and discharges to the river. The City also operates a reclaimed water distribution system (the only one of its kind in Tennessee) which provides irrigation to multiple commercial customers. In order to grow, the City must decide on critical infrastructure upgrades and future water resources to support increasing demand. This paper will describe the development of an integrated water resources plan (IWRP), incorporating potable water, wastewater, reclaimed water, and stormwater into a long-term plan identifying infrastructure improvements and policy recommendations .
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