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Blacksburg, VA, United States

Driskill N.M.,Virginia Polytechnic Institute and State University | Novak J.T.,Virginia Polytechnic Institute and State University | Goldsmith C.D.,Alternative Natural Technologies Inc.
Journal of Environmental Engineering (United States) | Year: 2014

Landfill leachates are often discharged through sewers or by trucks to publicly owned treatment works (POTWs) after on-site biological treatment. This discharge of landfill leachate is widely accepted because of its cost-effectiveness and reliability, but potential impacts of this practice include additional nutrient loading and interference with ultraviolet (UV) disinfection during subsequent biological treatment. Leachate was fractionated into humic acid (HA), fulvic acid (FA), and hydrophilic (Hpi) fractions based on chemical composition and solubility to determine the hydrophobicity distribution. The analysis showed that the specific UV254 absorbance (SUVA254) of the humic substances (HA and FA) was significantly higher than the Hpi fraction. The UV quenching materials were found to be resistant to biological treatment for the majority of leachates studied. Removal of humic substances was associated with decreased UV quenching and the aromatic content of landfill leachates after biological treatment. The size distribution of the hydrophilic fraction suggests that the majority of organic nitrogen in landfill leachate is associated with the low-molecular-weight (<1∈∈kDa) hydrophilic fraction. © 2014 American Society of Civil Engineers.

Chanton J.,Florida State University | Langford C.,Florida State University | Hater G.,Waste Management | Green R.,Waste Management | And 2 more authors.
Environmental Science and Technology | Year: 2011

Methane oxidation in landfill covers was determined by stable isotope analyses over 37 seasonal sampling events at 20 landfills with intermediate covers over four years. Values were calculated two ways: by assuming no isotopic fractionation during gas transport, which produces a conservative or minimum estimate, and by assuming limited isotopic fractionation with gas transport producing a higher estimate. Thus bracketed, the best assessment of mean oxidation within the soil covers from chamber captured emitted CH4 was 37.5 ± 3.5%. The fraction of CH4 oxidized refers to the fraction of CH4 delivered to the base of the cover that was oxidized to CO2 and partitioned to microbial biomass instead of being emitted to the atmosphere as CH4 expressed as a percentage. Air samples were also collected at the surface of the landfill, and represent CH4 from soil, from leaking infrastructure, and from cover defects. A similar assessment of this data set yields 36.1 ± 7.2% oxidation. Landfills in five climate types were investigated. The fraction oxidized in arid sites was significantly greater than oxidation in mediterranean sites, or cool and warm continental sites. Sub tropical sites had significantly lower CH4 oxidation than the other types of sites. This relationship may be explained by the observed inverse relationship between cover loading and fractional CH4 oxidation. © 2010 American Chemical Society.

Thoma E.D.,Office of Research and Development | Green R.B.,Waste Management | Hater G.R.,Waste Management | Goldsmith C.D.,Alternative Natural Technologies Inc. | And 3 more authors.
Journal of Environmental Engineering | Year: 2010

In 2006, the U.S. Environmental Protection Agency posted a new test method on its website called Other Test Method 10 (OTM 10) which describes direct measurement of pollutant mass emission flux from area sources using ground-based optical remote sensing. The method has validated application to relatively small bounded area sources but additional guidance is needed for large area sources, such as landfills, where the emission zone can exceed the size of optical configuration leading to difficulties in relating measured fluxes to emissions per unit area. This paper presents the findings of a series of tracer-release experiments designed to improve the understanding of OTM 10 in landfill applications. OTM 10 plume capture efficiency data acquired at a variety of landfill sites under a range of meteorological conditions and measurement configurations are presented. Experiments indicate an overall capture efficiency factor of 0.81 with a standard deviation of 0.33. Lower capture efficiencies from side slope releases are noted (0.69). The combined data set is analyzed for factors influencing capture efficiency. A multiple linear regression is used to model the capture efficiency as a function of primary parameters including distance of the tracer release from the observing plane and wind speed. A simplified model based on the regression analysis is described and its use for approximating the area contributing to flux is presented. © 2010 ASCE.

Gupta A.,Virginia Polytechnic Institute and State University | Zhao R.,Virginia Polytechnic Institute and State University | Zhao R.,Harbin Institute of Technology | Novak J.T.,Virginia Polytechnic Institute and State University | Douglas Goldsmith C.,Alternative Natural Technologies Inc.
Chemosphere | Year: 2014

When landfill leachate, with or without biological pretreatment, is discharged to publically owned treatment works (POTWs), it can interfere with the installed treatment facilities. Biological treatment is ineffective for the removal of some of the bio-refractory organic matter, including UV254 quenching substances. Fenton's reagent treatment for biologically treated landfill leachates is examined in this study as a polishing step to make landfill leachates acceptable to POTWs. The optimum conditions for the Fenton's reagent treatment are explored. The molecular weight and hydrophobic-hydrophilic nature based fractions of the Fenton's treated leachate samples are analyzed to provide insight into the leachate fractions targeted by the Fenton's reagent. The results indicate that Fenton's reagent can act as a good compliment to biological treatment as it can remove leachate fractions which are widely considered to be bio-refractory. It exhibited good UV254 absorbance removal by removing larger molecular weight humic substances and thus, can help solve the UV254 quenching problem due to leachates discharged to POTWs. © 2014 Elsevier Ltd.

Zhao R.,Virginia Polytechnic Institute and State University | Novak J.T.,Virginia Polytechnic Institute and State University | Goldsmith C.D.,Alternative Natural Technologies Inc.
Water Research | Year: 2012

A cost effective and widely applied approach for landfill leachate disposal is to discharge it to a municipal wastewater treatment plant (WWTP). The recalcitrant nature of leachate organics and the impact on the downstream WWTPs were comprehensively investigated in this study. Size fractionation by ultrafiltration (UF) and microfiltration (MF) was employed in conjunction with various analyses (TOC, COD, nitrogen species and UV 254 absorbance) on raw and biologically treated landfill leachates to provide insight into biological treatability. Overall, landfill leachate organics showed bio-refractory properties. Less than half of the organic matter, measured as total organic carbon (TOC), could be removed in the biological processes examined. Size distribution data showed that the <1 thousand Daltons (kDa) fraction is dominant in most untreated and treated landfill leachates, indicating difficulties for membrane treatment. Also, most removal occurred for the <1 kDa fraction in the biological processes, while the intermediate size fractions increased slightly. This may be caused by bio-flocculation and/or partial degradation of larger molecular weight fractions. Organic nitrogen was investigated in this study as one of the first explorations for landfill leachates. Organic nitrogen in landfill leachates was more bio-refractory than other organic matter. UV quenching by landfill leachates was also investigated since it interferes with the UV disinfection at WWTPs. The combination of activated carbon and activated sludge (PACT) showed some effectiveness for reducing UV quenching, indicating that carbon adsorption is a potential method for removal of UV quenching substances. Fourier transform Infrared (FT/IR) data showed that aromatic groups are responsible for the UV quenching phenomenon. © 2012 Elsevier Ltd.

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