Li Z.,Carbon Capture Scientific |
Buchberger S.G.,University of Cincinnati |
Clark R.M.,Environmental Engineering and Public Health Consultant |
Jeffrey Yang Y.,U.S. Environmental Protection Agency |
Swertfeger J.,Greater Cincinnati Water Works
Journal - American Water Works Association | Year: 2012
Full-scale field measurement and rapid small-scale column test data from the Greater Cincinnati (Ohio) Water Works (GCWW) were used to calibrate and investigate the application of the logistic model for simulating breakthrough of total organic carbon (TOC) in granular activated carbon (GAC) contactors. The logistic model parameters were estimated using a nonlinear regression algorithm. The calibrated logistic model was validated using data from multiple GAC contactors operating in parallel at the GCWW Richard Miller Treatment Plant. This facility has experienced large seasonal variations in flow rate and TOC influent concentration. Proper estimation of logistic model parameters depends on the run-time length of the GAC breakthrough data set. A critical minimum runtime threshold must be achieved to produce reliable parameter estimates. A properly calibrated logistic model provides an effective tool for accurately simulating the blended TOC concentrations in the GAC contactor effluent at a municipal drinking water treatment plant. © 2012 American Water Works Association.
Triantafyllidou S.,U.S. Environmental Protection Agency |
Lytle D.,U.S. Environmental Protection Agency |
Muhlen C.,U.S. Environmental Protection Agency |
Swertfeger J.,Greater Cincinnati Water Works
Water Research | Year: 2016
Tap water sampling and surface analysis of copper pipe/bathroom porcelain were performed to explore the fate of copper and silver during the first nine months of copper-silver ionization (CSI) applied to cold and hot water at a hospital in Cincinnati, Ohio. Ions dosed by CSI into the water at its point of entry to the hospital were inadvertently removed from hot water by a cation-exchange softener in one building (average removal of 72% copper and 51% silver). Copper at the tap was replenished from corrosion of the building's copper pipes but was typically unable to reach 200 μg/L in first-draw and flushed hot and cold water samples. Cold water lines had >20 μg/L silver at most of the taps that were sampled, which further increased after flushing. However, silver plating onto copper pipe surfaces (in the cold water line but particularly in the hot water line) prevented reaching 20 μg/L silver in cold and/or hot water of some taps. Aesthetically displeasing purple/grey stains in bathroom porcelain were attributed to chlorargyrite [AgCl(s)], an insoluble precipitate that formed when CSI-dosed Ag+ ions combined with Cl- ions that were present in the incoming water. Overall, CSI aims to control Legionella bacteria in drinking water, but plumbing material interactions, aesthetics and other implications also deserve consideration to holistically evaluate in-building drinking water disinfection. © 2016 Elsevier Ltd.
Dotson A.D.,University of Colorado at Boulder |
Keen V.S.,University of Colorado at Boulder |
Metz D.,Greater Cincinnati Water Works |
Linden K.G.,University of Colorado at Boulder
Water Research | Year: 2010
Ultraviolet (UV) irradiation has become popular as a primary disinfectant because it is very effective against Cryptosporidium and does not directly form regulated disinfection by-products. Higher UV doses and UV advanced oxidation (UV/H2O2) processes are under consideration for the treatment of trace organic pollutants (e.g. pharmaceuticals, personal care products). Despite the disinfection effectiveness of UV light, a secondary disinfectant capable of maintaining a distribution system residual is required to meet current U.S. regulation. This study investigated changes in disinfection by-product (DBP) formation attributed to UV or UV/H2O2 followed by application of free chlorine to quench hydrogen peroxide and provide residual disinfectant. At a UV dose of 1000mJ/cm2, trihalomethane (THM) yield increased by up to 4μg/mg-C and 13μg/mg-C when treated with low and medium pressure UV, respectively. With the addition of hydrogen peroxide, THM yield increased by up to 25μg/mg-C (5mg-H2O2/L) and 37μg/mg-C (10mg-H2O2/L). Although no changes in DBPs are expected during UV disinfection, application of UV advanced oxidation followed by chlorine addition was assessed with regard to impacts on DBP formation. © 2010 Elsevier Ltd.
Hong Y.,Greater Cincinnati Water Works |
Song H.,Sejong University |
Karanfil T.,Clemson University
Water Research | Year: 2013
The objective of this study was to investigate the roles of dissolved organic matter (DOM) fractions, pH and bromide concentration in the formation of haloacetic acids (HAA) during chloramination. DOM from two surface waters with a low (2.9 L/mg-m) and high (5.1 L/mg-m) specific UV absorbance (SUVA254) values was isolated and fractionated into three fractions based on the hydrophobicity [i.e., hydrophobic (HPO), transphilic (TPH) and hydrophilic (HPI)]. DOM mass balances and DBP reactivity checks were performed to characterize the effects of isolation and fractionation steps. The fractions were chloraminated at three pHs and three bromide concentrations. The results showed that pH was the most important factor controlling HAA formation and speciation. The HAA yields significantly decreased with increase in pH from 6.3 to 9.0. The impact of bromide in the formation of brominated HAA species also became less important with increasing pH, and no brominated specie was detectable at pH 9. HPO fractions of the two source waters consistently showed higher HAA yields than TPH and HPI fractions. On the other hand, HPI fractions showed higher bromine incorporation than HPO and TPH fractions. To maintain higher and relatively stable combined chlorine residuals while reducing HAA formation, water utilities may consider keeping pH above 7.5 as one strategy. This will also lower the formation of brominated HAA species which have been shown to be more cyto- and geno-toxic than their chlorinated analogs. © 2012 Elsevier Ltd.
Heringa M.B.,KWR Watercycle Research Institute |
Harmsen D.J.H.,KWR Watercycle Research Institute |
Beerendonk E.F.,KWR Watercycle Research Institute |
Reus A.A.,TNO |
And 4 more authors.
Water Research | Year: 2011
The objective of this study was to determine the genotoxic activity of water after UV/H2O2 oxidation and GAC filtration. Pre-treated surface water from three locations was treated with UV/H2O2 with medium pressure (MP) lamps and passed through granulated activated carbon (GAC). Samples taken before and after each treatment step were extracted and concentrated by solid phase extraction (SPE) and analyzed for genotoxicity using the Comet assay with HepG2 cells and the Ames II assay. The Comet assay showed no genotoxic response in any of the samples. In the Ames II, no genotoxic response was obtained with the TAMix (a mix of six strains), but the TA98 strain showed an increase in genotoxic activity after MP-UV/H2O2 for all three locations. GAC post treatment effectively reduced the activities to control levels at two of the three locations and to below the level of the pre-treated water at one site. The results indicate that UV/H2O2 treatment may lead to the formation of genotoxic by-products, which can be removed by subsequent GAC filtration. © 2010 Elsevier Ltd.