Effect of leachate recirculation on landfill gas production and leachate quality: A controlled laboratory study

Abstract

NOTICEThis report was prepared as a n account of work sponsored by an agency of the United States government.Neither the United States government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the 2.3. 4. 5.6. 7. 8.Comparison 4. 5.6. 7. 8.Detected constituents in landfill leachate at six sites @om With respect to questions 1, 3, and 4, considered together, the results indicated that there were no quantifiable benefits to leachate recirculation over leachate drainage with respect to methane production, carbon conversion, or leachate quality. Overall, through the decomposition process, the fraction of total carbon converted to biogas carbon ranged from about 0.10 (higher moisture content assays) to 0.50 (lower moisture content assays). The differences in carbon conversion were attributed to high rates of carboxylic acid production (exceeding consumption) in the higher moisture content assays. Cel1ulose:lignin ratios, a measure of decomposition, decreased from 4.3 (initial refuse without soil) to minimum values below 0.05 at the end of the experiment.Leachate quality was evaluated in two ways: changes in chemical concentrations through the leachatehecycle events and overall changes in constituent loading. Loading is calculated from the product of chemical concentration and moisture content to yield the total soluble mass present in a given assay. Calculation of loads addresses simple dilution effects from increased gravimetric moisture contents through the decomposition process. Linear relationships between chloride loads and other constituent loads suggested the contribution of dilution effects to observed leachate concentrations. For the recycle assays, since these were sampled only at the time of destruction, no net changes in liquid volume or leachate chemistry were introduced due I to periodic sampling. Thus, changes in gravimetric moisture content through decomposition could be carefully observed. For recycle assays where the initial moisture: dry solids ratios had initially been 3.2 to 3.2, the final ratios were 5.6 to 9.7; for assays which had higher initial ratios of 7.0 to 7.2, the final ratios were 12.2 to 15.4. With respect to the two soils in this study (question 2 above), they were added at small quantities to simulate the effects of soil cover and must be evaluated in parallel with refuse and leachate chemistry. For example, with respect to nitrogen, as a major nutrient, the total nitrogen content of the clay soil was higher than that of the sand soil, which might be expected to improve gas production rates from a...

Life Cycle Assessment (LCA) of Light-Weight Eco-composites

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Kinetics of Methane Oxidation in a Landfill Cover Soil: Temporal Variations, a Whole-Landfill Oxidation Experiment, and Modeling of Net CH4Emissions

“…Recent landfill studies have shown that methanotrophic CH 4 oxidation in aerated cover soils can be a major natural control on net CH 4 emissions ( − ), with rates as high as high as 166 g m -2 day -1 ( , ), indicating high capacities for CH 4 oxidation in landfill soils. Previous studies in nonlandfill soils suggest that high capacities may be observed in soils with historically elevated CH 4 fluxes ( − ). At landfill sites, “negative” CH 4 emissions (inward fluxes) have also been measured by several investigators using static enclosure (closed chamber) methods ( 4, 5, 7, 13, 14 ).…”