Gainesville, FL, United States
Gainesville, FL, United States

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McKnight T.,Jones Edmunds and Associates Inc. | Cho Y.M.,Geosyntec Consultants | Townsend T.G.,University of Florida | Choate A.,0 Environmental Loop South
Journal of Geotechnical and Geoenvironmental Engineering | Year: 2015

The cone penetration test (CPT) was evaluated as a tool for characterizing landfilled municipal solid waste (MSW). Cone penetration test soundings were performed at 16 locations in a closed MSW landfill in Florida, United States, where tip resistance (qt), sleeve friction resistance (fs), and friction ratio (fr) data were collected up to a depth of 10 m, and compared to waste properties from borings in the same location as five of the CPTs. The delineation of cover soil, waste, and subgrade soil was readily identifiable from the CPT data, but intermediate cover layers could not be discerned. At greater depths in the landfill, waste generally exhibited greater degradation with an average biochemical methane potential of 0.044 L CH4/g volatile solids versus shallower waste that was less degraded with an average BMP of 0.200 L CH4/g volatile solids. More degraded waste tended to have lower tip resistances of 3.6-3.7 MPa than less degraded waste that exhibited 5.0-5.4 MPa. The friction ratio tended to be greater for more degraded waste (2.8-3.2%) than less degraded waste (2.3-2.4%). The CPT data collected from the MSW landfill were also compared to conventional correlations to soil classification systems. The CPT data for more degraded waste generally correlated with finer soil classifications while CPT readings of less degraded waste corresponded to more coarse soils. © 2014 American Society of Civil Engineers.


Lee D.-U.,Jones Edmunds and Associates Inc. | Woo S.-H.,Kyung Nam Development Institute | Svoronos S.,University of Florida | Koopman B.,University of Florida
Water Research | Year: 2010

Denitrifying bacteria that are switched from oxic to anoxic conditions can experience diauxic lag, which is the time required for re-synthesis of nitrate reductase and other denitrifying enzymes. Pseudomonas denitrificans were exposed to alternating oxic/anoxic phases in a continuous flow reactor with either 4-h or 8-h anoxic phase lengths, in comparison to a measured diauxic lag of 9.5 h following steady-state oxic conditions. The P. denitrificans were unable to sustain anoxic growth at either of the anoxic phase lengths tested. Diauxic lag observed after several cycles of alternating oxic/anoxic phases was significantly longer than the diauxic lag measured after steady-state oxic conditions. This may be attributed to increase of cell maintenance energy requirements due to substrate accumulation during anoxic phases and concomitant high specific growth rates during oxic phases. © 2009 Elsevier Ltd. All rights reserved.


Kumar A.,University of Massachusetts Amherst | Kumar A.,Ghent University | Ergas S.J.,University of South Florida | Yuan X.,University of Massachusetts Amherst | And 4 more authors.
Journal of Chemical Technology and Biotechnology | Year: 2010

BACKGROUND: A diffusion and reaction model was developed for a hollow fiber membrane biofilm reactor (MBfR) to control nitric oxide (NO) emissions. In the MBfR, waste gases containing biodegradable compounds pass through the lumen of microporous hydrophobic hollow fiber membranes. Soluble, biodegradable compounds diffuse through the membrane pores and partition into a biofilm attached to the membranes where they are biodegraded. The membranes serve as a support for the microbial population and provide a large surface area for mass transfer. A dynamic model was developed for the MBfR which assumed biodegradation via Monod kinetics and constant biofilm thickness and density. Themodel was validated using experimental data from a study of NO removal (100 ppm) from a combustion gas mixture in a bench-scale MBfR with an acclimatized nitrifying population. RESULTS: NO gas was treated in a bench-scale MBfR at varying liquid recirculation velocities of 0.8 to 2.0 cm s-1. The gas residence time (τ ), calculated as themembrane lumen volume divided by the gas flow rate, was 1.9 s. NO removal efficiency for synthetic combustion gas ranged between 68% and 73% at room temperature (20 °C). CONCLUSION: The MBfR shows promise for treatment of waste gases from combustion processes. The model predicted an optimal liquid recirculation velocity of 1.5 cms-1 for NO removal, which is in good agreement with experimental data. Sensitivity experiments with the numeric model indicated that removal was a strong function of the biofilm density and the Monodmaximum specific growth rate (μmax). © 2010 Society of Chemical Industry.


Bukata B.J.,Jones Edmunds and Associates Inc. | Osborne T.Z.,University of Florida | Szafraniec M.L.,AMEC Environment and Infrastructure Inc.
Water, Air, and Soil Pollution | Year: 2015

Flatford Swamp, a 2800-acre forested wetland in east Manatee County, Florida, serves as the headwaters of the Myakka River. Over the last two decades, Flatford swamp has experienced significant tree mortality. The cause of this mortality, as well as dramatic encroachment of several invasive herbaceous and shrub species, is thought to be linked to hydrologic alterations that resulted in increased inundation during the wet and dry seasons. A biogeochemical characterization of wetland soils was conducted to (1) establish a baseline spatial distribution of soil P and N in Flatford Swamp, (2) determine if soil biogeochemistry could be related to tree mortality, and (3) determine if soil biogeochemical conditions may affect future restoration efforts. Mean total nitrogen and total carbon in sampled soils ranged from 13.8 to 24.9 mg kg-1 and 211 to 468 mg kg-1, respectively, indicating that soils are predominantly organic. Environmental conditions suggest that the nitrate-reduction process occurs readily in Flatford Swamp, and thus N abatement will continue naturally during restoration. Soil total phosphorus content is significantly higher than expected and is likely one of several contributing factors that led to observed changes in vegetation community structure. Levels of total sulfur, total calcium, and conductivity, indicative of agricultural use of groundwater for irrigation, suggest sulfide toxicity as a plausible contributing mechanism in the observed dieback of Nyssa sylvatica var. biflora. © 2015 Springer International Publishing Switzerland.


Hua G.,Jones Edmunds and Associates Inc. | Reckhow D.A.,University of Massachusetts Amherst
Water Research | Year: 2012

Bromine substitution factor (BSF) was used to quantify the effects of disinfectant dose, reaction time, pH, and temperature on the bromine substitution of disinfection byproducts (DBPs) during chlorination and chloramination. The BSF is defined as the ratio of the bromine incorporated into a given class of DBPs to the total concentration of chlorine and bromine in that class. Four classes of DBPs were evaluated: trihalomethanes (THMs), dihaloacetonitriles (DHANs), dihaloacetic acids (DHAAs) and trihaloacetic acids (THAAs). The results showed that the BSFs of the four classes of DBPs generally decreased with increasing reaction time and temperature during chlorination at neutral pH. The BSFs peaked at a low chlorine dose (1 mg/L) and decreased when the chlorine dose further increased. The BSFs of chlorination DBPs at neutral pH are in the order of DHAN > THM & DHAA > THAA. DHAAs formed by chloramines exhibited distinctly different bromine substitution patterns compared to chlorination DHAAs. Brominated DBP formation was generally less affected by the pH change compared to chlorinated DBP formation. © 2012 Elsevier Ltd.


Hamed A.,Jones Edmunds and Associates Inc. | Madani K.,Imperial College London | von Holle B.,University of Central Florida | Wright J.,University of Central Florida | And 2 more authors.
Environmental Management | Year: 2015

Sea level rise (SLR) is posing a great inundation risk to coastal areas. Some coastal nesting species, including sea turtle species, have experienced diminished habitat from SLR. Contingent valuation method (CVM) was used in an effort to assess the economic loss impacts of SLR on sea turtle nesting habitats for Florida coasts; and to elicit values of willingness to pay (WTP) of Central Florida residents to implement certain mitigation strategies, which would protect Florida’s east coast sea turtle nesting areas. Using the open-ended and dichotomous choice CVM, we sampled residents of two Florida communities: Cocoa Beach and Oviedo. We estimated the WTP of households from these two cities to protect sea turtle habitat to be between $42 and $57 per year for 5 years. Additionally, we attempted to assess the impact of the both the respondents’ demographics and their perception toward various situations on their WTP value. Findings include a negative correlation between the age of a respondent and the probability of an individual willing to pay the hypothetical WTP amount. We found that WTP of an individual was not dependent on prior knowledge of the effects of SLR on sea turtle habitat. The greatest indicators of whether or not an individual was willing to pay to protect sea turtle habitat were the respondents’ perception regarding the trustworthiness and efficiency of the party which will implement the conservation measures and their confidence in the conservation methods used. Respondents who perceive sea turtles having an effect on their life were also more likely to pay. © 2015 Springer Science+Business Media New York


PubMed | Jones Edmunds and Associates Inc., Imperial College London and University of Central Florida
Type: Journal Article | Journal: Environmental management | Year: 2016

Sea level rise (SLR) is posing a great inundation risk to coastal areas. Some coastal nesting species, including sea turtle species, have experienced diminished habitat from SLR. Contingent valuation method (CVM) was used in an effort to assess the economic loss impacts of SLR on sea turtle nesting habitats for Florida coasts; and to elicit values of willingness to pay (WTP) of Central Florida residents to implement certain mitigation strategies, which would protect Floridas east coast sea turtle nesting areas. Using the open-ended and dichotomous choice CVM, we sampled residents of two Florida communities: Cocoa Beach and Oviedo. We estimated the WTP of households from these two cities to protect sea turtle habitat to be between $42 and $57 per year for 5 years. Additionally, we attempted to assess the impact of the both the respondents demographics and their perception toward various situations on their WTP value. Findings include a negative correlation between the age of a respondent and the probability of an individual willing to pay the hypothetical WTP amount. We found that WTP of an individual was not dependent on prior knowledge of the effects of SLR on sea turtle habitat. The greatest indicators of whether or not an individual was willing to pay to protect sea turtle habitat were the respondents perception regarding the trustworthiness and efficiency of the party which will implement the conservation measures and their confidence in the conservation methods used. Respondents who perceive sea turtles having an effect on their life were also more likely to pay.


Osei K.,Hydro International | Mody A.,Jones Edmunds and Associates Inc. | Andoh R.Y.G.,Hydro International
World Environmental and Water Resources Congress 2010: Challenges of Change - Proceedings of the World Environmental and Water Resources Congress 2010 | Year: 2010

Often the design, permitting, construction and startup of an in-situ mechanical device in wastewater open channels is not the hardest task - demonstrating its performance against very stringent criteria after installation is a major challenge and may require a very creative design and delivery approach of its own. Most grit removal systems are not tested after installation and if there is a problem, operators find out only after the system breaks down or large quantities of grit are deposited in systems downstream of the grit removal process, affecting the entire wastewater treatment plant. In most instances these deficiencies cannot be rectified until the entire headworks is up for redesign. As a result of unreliable performance of prior (often conventional style) grit removal systems, some municipalities and clients are requesting that the efficacy of new, proprietary grit removal systems be proven either before they are installed or after installation. The testing usually consists of lab testing, pilot testing, field verification or a combination of these. A system that is unable to meet the treatment goals is either replaced or modified, usually at a cost to the supplier. This paper describes the test methods and sampling procedures used to evaluate two grit removal systems installed at two treatment plants in Clearwater, Florida. The work includes pilot testing for assessing the gradation of the incoming grit and in-situ device verification after the installation of the full-scale unit. The results from the testing indicate that using a multi-pronged approach to characterize grit and size treatment systems is an effective way of ensuring that the installed system is capable of meeting the design goals. The paper recommends adopting this test methodology for assessing installed grit removal systems. © 2010 ASCE.


PubMed | Jones Edmunds and Associates Inc.
Type: Journal Article | Journal: Water research | Year: 2012

Bromine substitution factor (BSF) was used to quantify the effects of disinfectant dose, reaction time, pH, and temperature on the bromine substitution of disinfection byproducts (DBPs) during chlorination and chloramination. The BSF is defined as the ratio of the bromine incorporated into a given class of DBPs to the total concentration of chlorine and bromine in that class. Four classes of DBPs were evaluated: trihalomethanes (THMs), dihaloacetonitriles (DHANs), dihaloacetic acids (DHAAs) and trihaloacetic acids (THAAs). The results showed that the BSFs of the four classes of DBPs generally decreased with increasing reaction time and temperature during chlorination at neutral pH. The BSFs peaked at a low chlorine dose (1 mg/L) and decreased when the chlorine dose further increased. The BSFs of chlorination DBPs at neutral pH are in the order of DHAN > THM & DHAA > THAA. DHAAs formed by chloramines exhibited distinctly different bromine substitution patterns compared to chlorination DHAAs. Brominated DBP formation was generally less affected by the pH change compared to chlorinated DBP formation.


PubMed | Jones Edmunds and Associates Inc.
Type: Journal Article | Journal: Water research | Year: 2010

Denitrifying bacteria that are switched from oxic to anoxic conditions can experience diauxic lag, which is the time required for re-synthesis of nitrate reductase and other denitrifying enzymes. Pseudomonas denitrificans were exposed to alternating oxic/anoxic phases in a continuous flow reactor with either 4-h or 8-h anoxic phase lengths, in comparison to a measured diauxic lag of 9.5h following steady-state oxic conditions. The P. denitrificans were unable to sustain anoxic growth at either of the anoxic phase lengths tested. Diauxic lag observed after several cycles of alternating oxic/anoxic phases was significantly longer than the diauxic lag measured after steady-state oxic conditions. This may be attributed to increase of cell maintenance energy requirements due to substrate accumulation during anoxic phases and concomitant high specific growth rates during oxic phases.

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