Stable isotopic determination of methane oxidation: When smaller scales are better.

Stable isotope measurements are an effective tool for evaluating methane (CH) consumption in landfill soils. However, determining the extent of CH oxidation in soils using this approach can be inherently biased, depending on characteristics of the study site and the sampling strategy that is employed. In this study, we establish the unusual case that sampling at smaller scales captures a better representation of the degree of oxidation occurring in landfill cover soils.

Comparison of Field Measurements to Methane Emissions Models at a New Landfill.

Estimates of methane emissions from landfills rely primarily on models due to both technical and economic limitations. While models are easy to implement, there is uncertainty due to the use of parameters that are difficult to validate. The objective of this research was to compare modeled emissions using several greenhouse gas (GHG) emissions reporting protocols including: (1) Intergovernmental Panel on Climate Change (IPCC); (2) U.

Liquid balance monitoring inside conventional, Retrofit, and bio-reactor landfill cells.

The Outer Loop landfill bioreactor (OLLB) in Louisville, KY, USA has been the site of a study to evaluate long-term bioreactor performance at a full-scale operational landfill. Three types of landfill units were studied including a conventional landfill (Control cell), a new landfill area that had an air addition and recirculation piping network installed as waste was being placed (As-Built cell), and a conventional landfill that was modified to allow for liquids recirculation (Retrofit cell). During the monitoring period, the Retrofit, Control, and As-Built cells received 48, 14, and 213LMg(-1) (liters of liquids per metric ton of waste), respectively.

The Outer Loop bioreactor: a case study of settlement monitoring and solids decomposition.

The Outer Loop landfill bioreactor (OLLB) located in Louisville, KY, USA has been in operation since 2000 and represents an opportunity to evaluate long-term bioreactor monitoring data at a full-scale operational landfill. Three types of landfill units were studied including a Control cell, a new landfill area that had a piping network installed as waste was being placed to support leachate recirculation (As-Built cell), and a conventional landfill that was modified to allow for liquid recirculation (Retrofit cell). The objective of this study is to summarize the results of settlement data and assess how these data relate to solids decomposition monitoring at the OLLB.

A new approach to characterize emission contributions from area sources during optical remote sensing technique testing.

Unlabelled: In the method termed "Other Test Method-10," the U.S. Environmental Protection Agency has proposed a method to quantify emissions from nonpoint sources by the use of vertical radial plume mapping (VRPM) technique.

Landfill methane oxidation across climate types in the U.S.

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 CH(4) was 37.

Observations on the methane oxidation capacity of landfill soils.

The objective of this study was to determine the role of CH(4) loading to a landfill cover in the control of CH(4) oxidation rate (gCH(4)m(-2)d(-1)) and CH(4) oxidation efficiency (% CH(4) oxidation) in a field setting. Specifically, we wanted to assess how much CH(4) a cover soil could handle. To achieve this objective we conducted synoptic measurements of landfill CH(4) emission and CH(4) oxidation in a single season at two Southeastern USA landfills.

Uncertainties associated with the use of optical remote sensing technique to estimate surface emissions in landfill applications.

Landfills represent a source of distributed emissions source over an irregular and heterogeneous surface. In the method termed "Other Test Method-10" (OTM-10), the U.S.

Evaluation of landfill gas decay constant for municipal solid waste landfills operated as bioreactors.

Prediction of the rate of gas production from bioreactor landfills is important for the optimization of energy recovery and for estimating greenhouse gas emissions. To improve the predictability of gas production, landfill gas (LFG) composition and flow rates were monitored for 4 yr from one conventional and two bioreactor landfill cells at the Outer Loop Landfill in Louisville, KY. The ultimate methane yield (L(o)) was estimated from the biochemical methane (CH4) potential of freshly buried refuse and the decay rate constant (k) was estimated from measured CH4 collection.

Effect of an acidic and readily-biodegradable non-hazardous industrial process waste on refuse decomposition.

Non-hazardous industrial process wastes are receiving increased interest from landfill owners, especially with respect to bioreactor operation. These wastes could benefit bioreactors as they represent sources of liquid, nutrients, and/or substrate as well as revenue. However, landfill operators should exercise caution in accepting these wastes, as some could have detrimental effects on refuse decomposition.

Effect of biosolids on refuse decomposition and phosphorus cycling.

Laboratory-scale reactors containing mixtures of municipal solid waste and wastewater treatment biosolids were monitored to assess the effect of biosolids on refuse decomposition and on phosphorus (P) cycling and speciation among orthophosphate, acid-hydrolysable P, and organic P. The co-disposal of 10 to 20% (by wet weight) aerobically-digested biosolids with residential refuse was compatible with refuse decomposition although the biosolids did not increase either the maximum methane production rate or the cumulative yield, and did not reduce lag times to the onset of methane production. The results of this study indicated that dissolved reactive phosphorus (DRP) was the dominant dissolved P fraction throughout refuse decomposition and that it was negatively correlated with the methane production rate and pH (r² = 0.

Effects of compost biocovers on gas flow and methane oxidation in a landfill cover.

Previous publications described the performance of biocovers constructed with a compost layer placed on select areas of a landfill surface characterized by high emissions from March 2004 to April 2005. The biocovers reduced CH(4) emissions 10-fold by hydration of underlying clay soils, thus reducing the overall amount of CH(4) entering them from below, and by oxidation of a greater portion of that CH(4). This paper examines in detail the field observations made on a control cell and a biocover cell from January 1, 2005 to December 31, 2005.

Release of trace organic compounds during the decomposition of municipal solid waste components.

Landfill gas contains numerous speciated organic compounds (SOCs) including alkanes, aromatics, chlorinated aliphatic hydrocarbons, alcohols, ketones, terpenes, chlorofluoro compounds, and siloxanes. The source, rate and extent of release of these compounds are poorly understood. The objective of this study was to characterize the release of SOCs and the regulated parameter, non-methane organic compounds (NMOCs) during the decomposition of residential refuse and its major biodegradable components [paper (P), yard waste (YW), food waste (FW)].

Relationships between analytical methods utilized as tools in the evaluation of landfill waste stability.

In this study, the refuse from 12 landfills of various ages ranging from fresh refuse to material 11 years old was collected, and changes in the bio-stability parameters were determined. The parameters measured included cellulose, lignin, biochemical methane potential (BMP) and volatile solids, along with plastics. These parameters, along with the cellulose to lignin ratio were compared to determine which were most indicative of the bio-stability of the refuse.

Nitrogen management in bioreactor landfills.

One scenario for long-term nitrogen management in landfills is ex situ nitrification followed by denitrification in the landfill. The objective of this research was to measure the denitrification potential of actively decomposing and well decomposed refuse. A series of 10-l reactors that were actively producing methane were fed 400 mg NO3-N /l every 48 h for periods of 19-59 days.