Brominated disinfection byproducts (DBPs) are a concern to drinking water utilities due to their ... more Brominated disinfection byproducts (DBPs) are a concern to drinking water utilities due to their toxicity and increasing prevalence in water systems. Haloacetic acids (HAAs) are a class of DBPs that are partially regulated by the United States Environmental Protection Agency (USEPA), but regulations are likely to increase as evidenced by the brominated HAAs listed on the USEPA Fourth Unregulated Contaminant Monitoring Rule and Fifth Contaminant Candidate List. Utilities often use a pre-oxidant to assist in their treatment training, but this can lead to increased HAA formation during treatment. In this study, tap water was spiked with bromine (Br2) at varying concentrations to simulate bromine-to-chlorine ratios found in the natural environment and the DBPs that may be formed from those waters. The water was fed through a bench-scale biological filter (biofilter) with a small layer of fresh granular activated carbon (GAC) media followed by acclimated anthracite media. The HAA species...
The long-term fate of three groups of petroleum biomarker compounds (terpanes, steranes, and tria... more The long-term fate of three groups of petroleum biomarker compounds (terpanes, steranes, and triaromatic steranes) was investigated in the Deepwater Horizon (DWH) oil spill residues collected from Alabama (USA) beaches over the past 10 years. This is the first study to investigate the long-term fate of these three groups of petroleum biomarkers in DWH oil spill samples over 10 years. We employed the highly recalcitrant C30 αβ-hopane as an internal biomarker to quantify the degradation levels of different biomarker compounds, and also to estimate the overall weathering levels of DWH oil spill residues. The data show that four lower molecular weight tricyclic terpanes (TR21, TR22, TR23, and TR24), three lower molecular weight steranes (S21, S22, and C27), and all triaromatic steranes degraded over the 10-year study period. All other terpanes (including hopanes) and steranes remained recalcitrant. There have been contradicting literature data on the degradation levels of homohopanes, and this field study demonstrates that all the homohopanes remained recalcitrant after 10 years of natural weathering. Our data also show that despite some degradation, the relative diagnostic ratios of the biomarkers remained stable for all three groups of biomarkers over the 10-year period.
Seasonal reconstructions of streamflow are valuable because they provide water planners, policy m... more Seasonal reconstructions of streamflow are valuable because they provide water planners, policy makers, and stakeholders with information on the range and variability of water resources before the observational period. In this study, we used streamflow data from five gages near the Alabama-Florida border and centuries-long tree-ring chronologies to create and analyze seasonal flow reconstructions. Prescreening methods included correlation and temporal stability analysis of predictors to ensure practical and reliable reconstructions. Seasonal correlation analysis revealed that several regional tree-ring chronologies were significantly correlated (p ≤ 0.05) with March–October streamflow, and stepwise linear regression was used to create the reconstructions. Reconstructions spanned 1203–1985, 1652–1983, 1725–1993, 1867–2011, and 1238–1985 for the Choctawhatchee, Conecuh, Escambia, Perdido, and Pascagoula Rivers, respectively, all of which were statistically skillful (R2 ≥ 0.50). The re...
B iological filtration (biofiltration) has a long history in drinking water treatment, starting w... more B iological filtration (biofiltration) has a long history in drinking water treatment, starting with slow sand filtration in the early 1900s. Biological activity, and thereby biodegradation, is promoted in conventional drinking water treatment filters by minimizing or eliminating any oxidant residual in the biofilter influent. In addition to particle removal, when filters are operated biologically, the natural microorganisms in and on the filter media biodegrade a range of organic and inorganic contaminants, with minimal to no additional energy or chemicals. Besides slow sand filters, the intentional use of biofiltration in North America was limited until the 2000s, although utilities have operated biofilters incidentally (i.e., have operated filters without an oxidant residual) for many years before that time. With the promulgation of the US Environmental Protection Agency’s Stage 1 and Stage 2 Disinfectants and Disinfection Byproducts Rules (DBPRs), many water utilities have shifted away from the practice of prefilter chlorination, thereby creating de facto rapid-rate biofilters in surface water treatment plants. Additionally, with the desire to sustainably remove an increasing array of contaminants (e.g., taste and odor compounds and emerging contaminants), the industry has been evaluating ways to optimize biofiltration performance to produce higher-quality drinking water and improve distribution system biostability.
Environmental Science: Water Research & Technology, 2018
This work identified and quantified the environmental impacts of conventional filtration, nonozon... more This work identified and quantified the environmental impacts of conventional filtration, nonozonated biofiltration, and ozonated biofiltration alternatives for a diverse set of source waters and treatment requirements.
Abstract A scale-up methodology was developed and verified that utilizes bench-scale biofilter re... more Abstract A scale-up methodology was developed and verified that utilizes bench-scale biofilter results to simulate field-scale (pilot or full scale), flow-through biofilter performance. This method...
Biodegradable organic matter (BOM), found in all surface waters, is a challenge for drinking wate... more Biodegradable organic matter (BOM), found in all surface waters, is a challenge for drinking water utilities because it can lead to distribution system bio-regrowth, react to form disinfection by-products, or be a specific compound of concern. A critical review of BOM (occurrence and oxidant effects) and rapid-rate biofiltration performance (preozonation, backwashing with an oxidant, empty bed contact time (EBCT) and temperature) was carried out. An extensive literature data analysis (n = 100) found total organic carbon (TOC) in nonozonated water is comprised of 20% (median) biodegradable organic carbon (BDOC) and 3% (median) assimilable organic carbon (AOC). For ozonated waters (n = 103), these values increased to 30% (median) BDOC and 9% (median) AOC. For all operation conditions (n = 117), biofilters (12 min average EBCT) removed 12% (median) of the influent TOC with higher removals for ozonated waters, 15% (median), compared to nonozonated waters, 10% (median). As temperature in...
Environmental Science: Water Research & Technology, 2017
Re-suspension of post-fire sediment deposits challenge conventional water treatment processes dur... more Re-suspension of post-fire sediment deposits challenge conventional water treatment processes during runoff events, impacting DBP formation. Treatment thresholds for a range of unit processes are established.
Brominated disinfection byproducts (DBPs) are a concern to drinking water utilities due to their ... more Brominated disinfection byproducts (DBPs) are a concern to drinking water utilities due to their toxicity and increasing prevalence in water systems. Haloacetic acids (HAAs) are a class of DBPs that are partially regulated by the United States Environmental Protection Agency (USEPA), but regulations are likely to increase as evidenced by the brominated HAAs listed on the USEPA Fourth Unregulated Contaminant Monitoring Rule and Fifth Contaminant Candidate List. Utilities often use a pre-oxidant to assist in their treatment training, but this can lead to increased HAA formation during treatment. In this study, tap water was spiked with bromine (Br2) at varying concentrations to simulate bromine-to-chlorine ratios found in the natural environment and the DBPs that may be formed from those waters. The water was fed through a bench-scale biological filter (biofilter) with a small layer of fresh granular activated carbon (GAC) media followed by acclimated anthracite media. The HAA species...
The long-term fate of three groups of petroleum biomarker compounds (terpanes, steranes, and tria... more The long-term fate of three groups of petroleum biomarker compounds (terpanes, steranes, and triaromatic steranes) was investigated in the Deepwater Horizon (DWH) oil spill residues collected from Alabama (USA) beaches over the past 10 years. This is the first study to investigate the long-term fate of these three groups of petroleum biomarkers in DWH oil spill samples over 10 years. We employed the highly recalcitrant C30 αβ-hopane as an internal biomarker to quantify the degradation levels of different biomarker compounds, and also to estimate the overall weathering levels of DWH oil spill residues. The data show that four lower molecular weight tricyclic terpanes (TR21, TR22, TR23, and TR24), three lower molecular weight steranes (S21, S22, and C27), and all triaromatic steranes degraded over the 10-year study period. All other terpanes (including hopanes) and steranes remained recalcitrant. There have been contradicting literature data on the degradation levels of homohopanes, and this field study demonstrates that all the homohopanes remained recalcitrant after 10 years of natural weathering. Our data also show that despite some degradation, the relative diagnostic ratios of the biomarkers remained stable for all three groups of biomarkers over the 10-year period.
Seasonal reconstructions of streamflow are valuable because they provide water planners, policy m... more Seasonal reconstructions of streamflow are valuable because they provide water planners, policy makers, and stakeholders with information on the range and variability of water resources before the observational period. In this study, we used streamflow data from five gages near the Alabama-Florida border and centuries-long tree-ring chronologies to create and analyze seasonal flow reconstructions. Prescreening methods included correlation and temporal stability analysis of predictors to ensure practical and reliable reconstructions. Seasonal correlation analysis revealed that several regional tree-ring chronologies were significantly correlated (p ≤ 0.05) with March–October streamflow, and stepwise linear regression was used to create the reconstructions. Reconstructions spanned 1203–1985, 1652–1983, 1725–1993, 1867–2011, and 1238–1985 for the Choctawhatchee, Conecuh, Escambia, Perdido, and Pascagoula Rivers, respectively, all of which were statistically skillful (R2 ≥ 0.50). The re...
B iological filtration (biofiltration) has a long history in drinking water treatment, starting w... more B iological filtration (biofiltration) has a long history in drinking water treatment, starting with slow sand filtration in the early 1900s. Biological activity, and thereby biodegradation, is promoted in conventional drinking water treatment filters by minimizing or eliminating any oxidant residual in the biofilter influent. In addition to particle removal, when filters are operated biologically, the natural microorganisms in and on the filter media biodegrade a range of organic and inorganic contaminants, with minimal to no additional energy or chemicals. Besides slow sand filters, the intentional use of biofiltration in North America was limited until the 2000s, although utilities have operated biofilters incidentally (i.e., have operated filters without an oxidant residual) for many years before that time. With the promulgation of the US Environmental Protection Agency’s Stage 1 and Stage 2 Disinfectants and Disinfection Byproducts Rules (DBPRs), many water utilities have shifted away from the practice of prefilter chlorination, thereby creating de facto rapid-rate biofilters in surface water treatment plants. Additionally, with the desire to sustainably remove an increasing array of contaminants (e.g., taste and odor compounds and emerging contaminants), the industry has been evaluating ways to optimize biofiltration performance to produce higher-quality drinking water and improve distribution system biostability.
Environmental Science: Water Research & Technology, 2018
This work identified and quantified the environmental impacts of conventional filtration, nonozon... more This work identified and quantified the environmental impacts of conventional filtration, nonozonated biofiltration, and ozonated biofiltration alternatives for a diverse set of source waters and treatment requirements.
Abstract A scale-up methodology was developed and verified that utilizes bench-scale biofilter re... more Abstract A scale-up methodology was developed and verified that utilizes bench-scale biofilter results to simulate field-scale (pilot or full scale), flow-through biofilter performance. This method...
Biodegradable organic matter (BOM), found in all surface waters, is a challenge for drinking wate... more Biodegradable organic matter (BOM), found in all surface waters, is a challenge for drinking water utilities because it can lead to distribution system bio-regrowth, react to form disinfection by-products, or be a specific compound of concern. A critical review of BOM (occurrence and oxidant effects) and rapid-rate biofiltration performance (preozonation, backwashing with an oxidant, empty bed contact time (EBCT) and temperature) was carried out. An extensive literature data analysis (n = 100) found total organic carbon (TOC) in nonozonated water is comprised of 20% (median) biodegradable organic carbon (BDOC) and 3% (median) assimilable organic carbon (AOC). For ozonated waters (n = 103), these values increased to 30% (median) BDOC and 9% (median) AOC. For all operation conditions (n = 117), biofilters (12 min average EBCT) removed 12% (median) of the influent TOC with higher removals for ozonated waters, 15% (median), compared to nonozonated waters, 10% (median). As temperature in...
Environmental Science: Water Research & Technology, 2017
Re-suspension of post-fire sediment deposits challenge conventional water treatment processes dur... more Re-suspension of post-fire sediment deposits challenge conventional water treatment processes during runoff events, impacting DBP formation. Treatment thresholds for a range of unit processes are established.
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