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This study examines the influence of chlorine disinfectant type, water use frequency (stagnation time), and water heater temperature on the growth and persistence of microbes, including nontuberculous mycobacteria (NTM), in water heater storage tanks and downstream plumbing. The experimental setup consists of four 50-gallon electric water heater tanks at two different locations that provide different types of secondary disinfectant (chloramine and free chlorine). The water heaters were operated at two different temperature settings (45°C ± 3°C and 60°C ± 3°C), and with two different use patterns (once per 24 h and three times per 24 h), which allowed for sampling at three different stagnation times: overnight, 16-h stagnation, and 3-h stagnation. Microbial analyses were conducted on water samples collected at the tank effluent and the shower head to compare the water quality in the tank before the stagnation period and in the piping downstream of the tank after the stagnation period. The results indicated that culturable NTM was not detected under any of the conditions studied in the free chlorine disinfectant system. In the chloramine system, higher water use frequency (equivalent to 180 gallons/day) and higher water heater temperature (60°C ± 3°C) decreased the number of heterotrophic bacteria in the tank and the piping downstream to the tank but failed to control NTM. For both heterotrophic plate count and NTM, the piping downstream was not more microbially active than the tank. [ABSTRACT FROM AUTHOR]

Flowback water is the solution that returns to the surface following completion of the hydraulic fracturing process during natural gas extraction. This study examines and analyzes the constituents that make up flowback waters collected from various drilling sites in Marcellus shale formation in the states of Pennsylvania, New York, and West Virginia. Flowback sampling data were collected from four different sources (the Environmental Protection Agency, Gas Technology Institute; Pennsylvania Department of Environmental Protection; Bureau of Oil and Gas Management; and the New York Department of Environmental Conservation) and compiled into one database with a total of 35,000 entries. Descriptive statistical analysis revealed high concentrations of chlorinated solvents, disinfectants, dissolved metals, organic compounds, radionuclides, and total dissolved solids. A one-way ANOVA test revealed that over 60% of the constituents tested displayed significant differences (significance level = 0.05) in mean concentrations among the four data sources. Relative prioritization scores were developed for 58 constituents by dividing observed mean concentrations by the maximum contamination level (MCL) guidelines for drinking water. The following constituents were found to have mean concentrations over 10 times greater than the MCL: 1,2-dichloroethane, antimony, barium, benzene, benzo(a)pyrene, chloride, dibromochloromethane, gross alpha, iron, manganese, pentachlorophenol, radium, and thallium, and vinyl chloride. Concentrations of anthropogenic chemicals are tightly correlated with each other, but not with chloride concentrations, and not with naturally occurring inorganics and radionuclides. [ABSTRACT FROM AUTHOR]

Flowback water is the solution that returns to the surface following completion of the hydraulic fracturing process during natural gas extraction. This study examines and analyzes the constituents that make up flowback waters collected from various drilling sites in Marcellus shale formation in the states of Pennsylvania, New York, and West Virginia. Flowback sampling data were collected from four different sources (the Environmental Protection Agency, Gas Technology Institute; Pennsylvania Department of Environmental Protection; Bureau of Oil and Gas Management; and the New York Department of Environmental Conservation) and compiled into one database with a total of 35,000 entries. Descriptive statistical analysis revealed high concentrations of chlorinated solvents, disinfectants, dissolved metals, organic compounds, radionuclides, and total dissolved solids. A one-way ANOVA test revealed that over 60% of the constituents tested displayed significant differences (significance level=0.05) in mean concentrations among the four data sources. Relative prioritization scores were developed for 58 constituents by dividing observed mean concentrations by the maximum contamination level (MCL) guidelines for drinking water. The following constituents were found to have mean concentrations over 10 times greater than the MCL: 1,2-dichloroethane, antimony, barium, benzene, benzo(a)pyrene, chloride, dibromochloromethane, gross alpha, iron, manganese, pentachlorophenol, radium, thallium, and vinyl chloride. Concentrations of anthropogenic chemicals are tightly correlated with each other, but not with chloride concentrations, and not with naturally occurring inorganics and radionuclides. [ABSTRACT FROM AUTHOR]

A response from the authors of the article "Characterization of Marcellus Shale Flowback Water" in the 2014;31(9) issue is presented.