Refuse Landfill Research Articles

Settlement of recently placed domestic refuse landfill : Watts, K S; Charles, J A Inst Civ Engrs ProcV88, Pt 1, Dec 1990, P971–993

Settlement of recently placed domestic refuse landfill : Watts, K S; Charles, J A Inst Civ Engrs ProcV88, Pt 1, Dec 1990, P971–993

Environmental effects of landfills

In the past, landfilling involved burying municipal refuse directly or after on-site burning. Typically, little attention was given to proper siting and engineering to obviate the hazards of the generation of CH 4 and toxic leachates as wastes decomposed. Leachates were hopefully attenuated by natural processes (adsorption, precipitation, ion exchange, microbial decomposition or dilution in the unsaturated zone below landfills). Landfills slowly evolved by proper siting, design and management into efficiently operated bioreactors to produce purified CH 4 for use as a fuel, and leachates, which were treated biologically and chemically to minimize groundwater pollution. Microbial reactions in landfills are outlined. The amounts and composition of landfill gas and leachate as determined by the interaction of factors such as refuse composition, degree of compaction, temperature, moisture content, refuse age and depth are discussed. Typical inorganic and organic composition of landfill gases and leachates are presented. The potential and real environmental effects on soils, plants, groundwater, aquatic organisms and humans of disposal of municipal refuse by landfilling are reviewed. Finally, the most recent trend in constructing refuse landfills to serve as final storage reservoirs which are deliberately kept dry to minimize gas and leachate production is discussed and illustrated. Present activities in waste recycling to conserve landfill space are outlined.

Municipal Solid Waste Management—an Example of a Partnership Between Five Municipalities

Throughout the 1970s and 1980s many joint municipal partnerships were established in Denmark to take responsibility for the planning and handling of waste on behalf of municipalities in the partnership. RENO SYD is a typical joint municipal partnership, established to handle the municipal solid waste of five municipalities with a total of 65,000 inhabitants. The paper reviews the by-laws and organization of RENO SYD; the facility financing ownership or leasing; the collection of the various waste types; the reception at recycling cites; the refuse treatment, energy recovery, waste separation, treatment and landfill disposal; recycling; and economics, including tipping fees and taxation.

Mathematical Fate Modeling of Hazardous Organic Pollutants During Codisposal with Municipal Refuse

ABSTRACT A mathematical mass transport model, the Vadose Zone Interactive Processes model, was employed to describe the fate of organic compounds codisposed in municipal refuse landfills. The model...

Construction of a highway on a sanitary landfill and its long-term performance : Burlingame, M J Trans Res Rec N1031, 1985, P34–40

The short- and long-term (4-5 yr) settlements of the Interstate 85 roadway in New Jersey, which was constructed on a sanitary landfill, are presented in this paper. Published, long-term settlement behavior of other structures constructed on refuse landfills are also presented for comparison. Stabilization of the landfill was accomplished by placing a pad of granular fill between the landfill and proposed pavement and then surcharging. Measured short- and long-term settlements are compared to those calculated from formulas developed on the basis of the behavior of sanitary landfill materials elsewhere. These equations were used to make conservative predictions of the measured settlements. Stabilization of the landfill with a heavier surcharge than is minimally required appeared to greatly reduce long-term settlements. A recent visual inspection of the roadway showed that it had no structural damage and little observable differential settlement.

Changes in the organic fraction of leachate from two domestic refuse sites on the Sherwood Sandstone, Nottinghamshire

Summary Two domestic refuse landfill sites, situated on the outcrop of the Sherwood Sandstone in Nottinghamshire, have been investigated with a view to elucidating possible mechanisms of attenuation in operation within the unsaturated zone. Two cored boreholes have been drilled at each site, separated by a two-year interval, and the pore water analysed for a wide range of parameters. Although acetogenic degradation has been identified within both landfills, and it is postulated that methanogenesis is occurring in the Gorsethorpe site, there is little evidence for attenuation of the organic fraction of the leachate within the 6 m of unsaturated zone penetrated.

Methane generation and microbial activity in a domestic refuse landfill site

Carboxylic acid and sulphate concentrations, microbial activity as estimated by extracellular enzyme activities, and biogas production, at Aveley Landfill Site (Essex) were markedly influenced by refuse moisture content, which depended on the level of the water table. Cellulose: lignin ratios were indicative of cellulose disappearance and enzyme activity determinations may be a measure of the potential of landfill sites to produce biogas.

Evaluation of experimental conditions in batch leaching procedures

A batch leaching test is a rapid and inexpensive way to evaluate the potential hazardousness of a waste disposed to land. Several batch leaching tests are currently being used, however, the conditions under which these tests are conducted vary considerably. Research was undertaken to evaluate the sensitivity of main test variables on contaminant release, and to examine interactions among these variables. Nine different methods of agitating a test sample were evaluated. Some techniques gave results that were comparable to those obtained when the test sample was simply allowed to remain at rest. Others were too severe and caused fragmentation of the waste particles. A tumbler was judged to best meet the criteria established for an acceptable agitation method. A 2 5 factorial experiment was performed to examine the effect of the following test conditions on contaminant release: leaching medium, liquid-to-solid ratio, number of elutions, particle size and time of elution. The first three conditions had the largest effect on test results. Contaminant release patterns over a 24 hour period were different using distilled water and an acidic solution as leaching media. The effect on contaminant release of different leaching media was also examined. Synthetic leachates modelled on municipal refuse landfill leachates were more aggressive in effecting contaminant release than distilled water or two acidic solutions. Finally, liquid-solid separation of a waste sample prior to leaching had a relatively small effect on contaminant release, compared to the effect of using different leaching media or liquid-to-solid ratios.

Influence of soil gas contamination on tree root growth

Rooted-cuttings and saplings of green ash (Fraxinus lanceolata) and hybrid poplar (Populus spp) were planted on a former municipal refuse landfill and on a nearby nonlandfill control plot. The root systems of four trees of each species and size were excavated on the landfill plot-two growing in an area where the concentrations of anaerobic landfill gases were relatively high and two in a relatively low-gas area. Two trees of each species and size were also excavated on the control. The root systems of both species were significantly shallower on the landfill plot than on the control. Green ash appeared to avoid the adverse gas environment of the deeper soil layers on the landfill by producing adventitious roots. Hybrid poplar became adapted in a different manner, by redirecting root growth from the deepter soil layers to the soil surface.

Landfill Gas, What It Does to Trees, and How Its Injurious Effects May Be Prevented

The conversion of former refuse landfills into post closure uses generally involves the planting of trees for aesthetic and occasionally commercial purposes. The authors have noted that it is frequently difficult to obtain satisfactory tree growth when the gases of anaerobic decomposition of the organic matter contained in the refuse are present. The lack of oxygen and the presence of excessive quantities of carbon dioxide in the soil root zone appear to be the cause of much tree injury and death when the trees are grown above or adjacent to former refuse fills. Thin, low-nuthent-content cover soils, lack of adequate soil moisture, excessive compaction, and surface settlement have also been identified as problems found associated with former refuse deposit areas. Methods are suggested for preventing the entry of landfill gases into the root zones of the trees and in accommodating other tree growth problems found associated with former refuse dumping areas. These include gas venting and blocking, irrigation, planting adaptable species, using small sized specimens in preference to large, and providing adequate maintenance.

Optimisation of methane production and refuse decomposition in landfills by temperature control

AbstractThe major contributions to the thermal regime of an anaerobic domestic refuse landfill are identified and quantified. These are heat of reaction, specific heat of water/refuse mixtures, heats of neutralisation, heat losses to air and soil, solar radiation and aerobic metabolism. It is shown that even in temperate climates, landfill temperatures can rise to 45°C and above under anaerobic conditions with the concomitant reduction in fatty acid concentrations in leachate. This has been confirmed with field observations. Management requirements for establishing and maintaining temperatures of about 45°C in an anaerobic landfill are identified. Principally these involve allowing water into the site from the bottom and maintaining an insulating layer of refuse of about 4 m above the water‐table in the landfill. The advantages of a bioreactive landfill are briefly discussed.

Damage to Woody Species by Anaerobic Landfill Gases

Refuse landfills are constructed on areas of land set aside for depositing solid waste. Current practice dictates that the refuse be spread and compacted, before being covered daily with a 6in. layer of soil., for environmental protection, to save space, and to reduce the amount of settlement that will take place in the area after the landfill is completed. Soil cover is placed over the refuse to improve aesthetics; prevent papers from blowing; reduce odors; control insects, rodents and birds; reduce the hazard of fire; and reduce water infiltration into the refuse. The initial soil cover is supposed to be increased from 6 in to a 12-in-thick intermediate cover after a limited period of time, and the final soil cover for the refuse is supposed to be at least 2 ft deep. Many landfills have been completed, however, with less than 2 ft of soil over their top surface. It is in this top layer of soil cover that any vegetative cover will be planted. Although many uses have been proposed for completed landfills, experience has shown that they are generally unsuitable for excavation or for construction purposes. Open-space recreational areas, such as parks, playgrounds, picnic areas, and golf courses, therefore, are deemed to be a suitable use for such sites. In some locations attempts have been made to use the completed landfills for agricultural purposes. Depending on the composition of the fill and the environmental conditions within it, however, there are serious inherent disadvantages, not the least of which are ecological upsets due to pollution of water supplies, the production of toxic and explosive gas mixtures from anaerobic microbial decomposition of the organic matter present and surface settlement. Excessive landfill ground temperatures have also been reported. Prior to 1965 landfills were frequently operated as open-burning dumps. While this caused air pollution and vector control problems at the time of their operation, the result was that most of the material left in the landfill was nonbiodegradable, resulting in much less ultimate settlement of the landfill and much less anaerobic gas development after the landfill was closed. The present-day landfill does not permit open burning; therefore, it provides more nutrients for the microorganisms that generate the gases, mainly carbon dioxide and methane, that present problems for growing vegetation. High concentrations of carbon dioxide in the root zone of plants, have been reported to be directly toxic to vegetation (4,5). Although methane has not been reported to be phytotoxic per se, perhaps, when combined with the carbon dioxide, it can remove oxygen from the root zone of the vegetation by direct displacement, by utilization of the oxygen by methane-consuming bacteria, or by a combination of these. The end

Recent Developments in the Use of Municipal Refuse as a Fuel

The increase in the price of fuel since the Near East war of 1973 has led to renewed interest in refuse as a fuel, starting with more accurate knowledge of its calorific value. No further large power plant has been built but there have been incinerators supplying steam for heating purposes. The use of refuse as supplementary fuel for boiler plant and for cement production and as fuel for burning sewage sludge. Experiments are in progress on refuse in pelletised form for general sale and on pyrolysis and hydrolysis. In the USA there is interest in gas production from refuse landfills.

Geologic aspects of landfill refuse disposal

The decomposition of solid waste materials in sanitary landfills produces liquids and gases which are deleterious to human beings, animals, plants and inorganic geologic materials. This paper presents a summary of leachate characteristics and discusses the effects of leachate on groundwater quality and carbonate strata. A system for site evaluation for purposes of sanitary landfill is also presented. The characteristics of the soil and rock at a site are included in the evaluation system through assessment of their infiltration potential, permeability, filtering capability and absorption potential. The characteristics of the groundwater at a site are taken into consideration through assessment of the substrate potential, buffering capacity and distributive potential (for contaminants). Formulae are stated to allow determination of evaluation parameters, and an example of the application of the rating system is presented. Use of the site-evaluation system will improve the quality of site selection and will reduce contamination and pollution problems created by construction of refuse landfills at unsuitable locations.