Showing papers on "Bioreactor landfill published in 2007"
TL;DR: In this article, the potential for additional collection and utilization of landfill gas in the US and worldwide was estimated based on the landfill gas situation in the United States and worldwide, and a conservative estimate of methane generation of about 50 nm3 of methane per ton of municipal solid waste (MSW) landfilled was made.
541 citations
TL;DR: Analyzing bioreactor and recirculation landfills in North America indicated that more detailed data collection over longer time periods is needed to draw definitive conclusions regarding the effects of biore Actor and Recirculation operations.
265 citations
TL;DR: Aerobic leachate recirculated landfill appears to be the most effective option in the removal of organic matter and ammonia.
202 citations
TL;DR: The role of refuse pretreatment, placement methods and water management techniques in the control and stimulation of refuse fermentation are also discussed in this paper, where it is concluded that there is no requirement for added nitrogen and phosphorus sources.
Abstract: Landfill sites containing domestic refuse should be managed so as to optimise methane production when hydrogeological conditions permit. On large sites this would be both economically profitable and environmentally desirable as uncontrolled pollution would be minimised and sites could be reclaimed as quickly as possible. Landfill microbiology has been confined to public health aspects, and clearly, further microbiological studies are required to optimise the degradation of carbon compounds. Knowledge of the fate of synthetic polymers is poor. It is interesting to consider whether they constitute a reservoir of delayed-potential methane generation. Contrary to previous ideas it is concluded that there is no requirement for added nitrogen and phosphorus sources. The interaction of refuse density and water content is identified as a major factor which must be controlled to optimise methane generation. The high solids content and reactivity of this anaerobic bioreactor coupled with the poor thermal conductivity of refuse enables the landfill to generate and sustain high temperatures. The roles of refuse pretreatment, placement methods and water management techniques in the control and stimulation of refuse fermentation are also discussed.
152 citations
TL;DR: A neural network model for predicting the methane fraction in landfill gas originating from field-scale landfill bioreactors and evaluated the anaerobic conversion efficiencies based on leachate characteristics during different time periods.
Abstract: In this study we present a neural network model for predicting the methane fraction in landfill gas originating from field-scale landfill bioreactors. Landfill bioreactors were constructed at the Odayeri Sanitary Landfill, Istanbul, Turkey, and operated with (C2) and without (C1) leachate recirculation. The refuse height of the test cell was 5m, with a placement area of 1250m^2 (25mx50m). We monitored the leachate and landfill gas components for 34 months, after which we modeled the methane fraction in landfill gas from the bioreactors (C1 and C2) using artificial neural networks; leachate components were used as input parameters. To predict the methane fraction in landfill gas as a final product of anaerobic digestion, we used input parameters such as pH, alkalinity, Chemical Oxygen Demand, sulfate, conductivity, chloride and waste temperature. We evaluated the anaerobic conversion efficiencies based on leachate characteristics during different time periods. We determined the optimal architecture of the neural network, and advantages, disadvantages and further developments of the network are discussed.
147 citations
TL;DR: A detailed review of the literature on methane bio-filtration is presented in this article, where microorganisms, mainly the methanotrophs, involved in the methane biodegradation process, and their needs in terms of oxygen and carbon dioxide utilization are described.
Abstract: The production of biogas in landfills, its composition and the problems resulting from its generation are all reviewed. Biofiltration is a promising option for the control of emissions to atmosphere of the methane contained in biogas issued from the smaller and/or older landfills. A detailed review of the methane biofiltration literature is presented. The microorganisms, mainly the methanotrophs, involved in the methane biodegradation process, and their needs in terms of oxygen and carbon dioxide utilization, are described. Moreover, the influence of nutrients such as copper, nitrogen and phosphorus, and the process operating conditions such as temperature, pH and moisture content of the biofilter bed, are also presented. Finally, the performance of various filter beds, in terms of their elimination capacities, is presented for laboratory scale biofilters and landfill covers.
138 citations
TL;DR: In this article, the first-order gas generation model parameters were estimated for the US EPA landfill gas emissions model (LandGEM) through statistical comparison of predicted and actual gas collection.
127 citations
TL;DR: In this article, the major contributions to the thermal regime of an anaerobic domestic refuse landfill are identified and quantified, including heat of reaction, specific heat of water/refuse mixtures, heat of neutralisation, heat losses to air and soil, solar radiation and aerobic metabolism.
Abstract: The 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.
105 citations
TL;DR: In this article, the authors present settlement mechanisms and the methods for estimating settlements of municipal solid waste landfills, including bioreactors, based on results of field monitoring and data in published literature, coefficients of secondary compression for solid waste due to self-weight and external load.
Abstract: This paper presents settlement mechanisms and the methods for estimating settlements of municipal solid waste landfills, including bioreactor landfills. Based on results of field monitoring and data in published literature, coefficients of secondary compression for solid waste due to self-weight and external load are estimated. Special considerations are given to bioreactor landfills. Uses of these coefficients for long-term settlement estimation and their application to postclosure maintenance and development plans are discussed. Four case histories illustrating the use of these coefficients are presented. Methods of landfill treatment to reduce settlements are also presented.
84 citations
TL;DR: The results showed that the sequential anaerobic-aerobic process might remove above 90% of COD and near to 100% of NH4+ -N from leachate under the optimum organic loading rate (OLR).
82 citations
TL;DR: The landfilling sub- model used in the life-cycle assessment program EASEWASTE is described, and some of the implications of this sub-model are examined.
TL;DR: The well diameter, hydraulic conductivity of the well drainage pack, and screen height and screen depth of theWell have very little effect on the wetted width for a given liquid flux, while the liquid injection flux increases with the decrease in hydraulic conductivities of the leachate collection system.
TL;DR: In this article, the in situ aerated former Kuhstedt Landfill (district of Rotenburg (Wumme), Germany was assessed regarding the possibility of reducing the emitted amounts of greenhouse gases (GHG; here methane), and it was demonstrated that more than 72% of the total GHG emissions occurring under anaerobic conditions could be avoided by altering the ambient aerobic/oxidizing conditions.
TL;DR: A computer program was developed to numerically predict the settlements and gas pressures in a bioreactor landfill using landfill geometry and waste properties, and produced satisfactory trends of the settlement and the landfill gas pressure profiles.
TL;DR: Results of the study show that the metal content of landfill leachate samples is not a major concern for both aerobic and anaerobic landfills.
TL;DR: The regimes of leachate recirculation should be adjusted to the phases of waste stabilization to enhance efficiency of energy recovery and Integrated with the strategy of in situLeachate management, extra pre-treatment or post-treatment methods to remove the nutrients are recommended.
TL;DR: The effects of three pretreatments of leachate on the refuse stabilization efficiency were investigated and it was shown that pretreatment using an anaerobic upflow filtration bioreactor or a well-decomposed waste layer could reduce the COD and provide methanogens, both were beneficial to establish early methanogenesis status.
14 Oct 2007
TL;DR: This study shows that the ERT can be a useful noninvasive technique to monitor the moisture content of MSW and to assess the effectiveness of recirculation systems at bioreactor landfills.
Abstract: The changes in electrical resistivity of municipal solid waste (MSW) measured with electrical resistivity tomography (ERT) have been used to assess the influence of leachate recirculation events at bioreactor landfills. An attempt is made in this study to develop a direct correlation between the electrical resistivity and the moisture content of MSW. This correlation is based on a field testing program at Orchard Hills landfill (Illinois, USA) that included (1) ERT at three different locations that have been subjected to leachate recirculation events, and (2) moisture content of waste samples obtained at different depths from boreholes at the same three locations of ERT. It is shown that Archie’s law can reasonably correlate the electrical resistivity and the moisture content of the waste; however, the two parameters, a and m, needed for the correlation appear to depend on the specific waste conditions. For the studied waste, the best fitted parameter a is 0.75 and the parameter m ranges from 1.6 to 2.15. Using this correlation, the influence of leachate recirculation on the distribution of moisture content at three locations of the landfill is evaluated. This study shows that the ERT can be a useful noninvasive technique to monitor the moisture content of MSW and to assess the effectiveness of recirculation systems at bioreactor landfills.
TL;DR: This research investigates the implementation of a novel methane emission control technique that involves thin biocovers placed as intermediate waste covers to oxidize methane without affecting the operation of bioreactor landfills.
TL;DR: Reduction of volatile solids content in waste samples along the depth of landfill suggests that biodegradation of solid waste has taken place to a greater extent at the bottom of the landfill.
Abstract: Solid waste characteristics and landfill gas emission rate in tropical landfill was investigated in this study. The experiment was conducted at a pilot landfill cell in Thailand where fresh and two-year-old wastes in the cell were characterized at various depths of 1.5, 3, 4.5 and 6 m. Incoming solid wastes to the landfill were mainly composed of plastic and foam (24.05%). Other major components were food wastes (16.8%) and paper (13.3%). The determination of material components in disposed wastes has shown that the major identifiable components in the wastes were plastic and foam which are resistant to biodegradation. The density of solid waste increased along the depth of the landfill from 240 kg m−3 at the top to 1,260 kg m−3 at the bottom. Reduction of volatile solids content in waste samples along the depth of landfill suggests that biodegradation of solid waste has taken place to a greater extent at the bottom of the landfill. Gas production rates obtained from anaerobic batch experiment were in agreement with field measurements showing that the rates increased along the depth of the landfill cell. They were found in range between 0.05 and 0.89 l kg−1 volatile solids day−1. Average emission rate of methane through the final cover soil layer was estimated as 23.95 g−2day−1 and 1.17 g−2day−1 during the dry and rainy seasons, respectively.
TL;DR: A field scale trial is being undertaken at a landfill site in Sydney, Australia, to investigate passive drainage and biofiltration of landfill gas as a means of managing landfill gas emissions at low to moderate gas generation landfill sites.
TL;DR: Encouraging microbial degradation of solid waste in landfill bioreactors to enhance the mining process needs to be demonstrated at pilot scale to complement the ongoing researches in Asian context.
Abstract: Landfill mining is the process to recover recyclable materials, landfill space and compost. The paper presents the concepts of mining of compost from open stabilised dumpsites and bioreactor landfills to make landfills sustainable. Studies indicate that 50% of the material from the dumpsite could be recovered and reused as compost for non-edible plants or cover material for daily use in the dumpsites. Encouraging microbial degradation of solid waste in landfill bioreactors to enhance the mining process needs to be demonstrated at pilot scale to complement the ongoing researches in Asian context.
TL;DR: In this article, an advanced MBR system incorporating nanofiltration was successfully used to clean landfill leachate and establish a compact, sustainable solution, which was used in a project at Wehrle Environmental.
Abstract: Tony Robinson, general manager at Wehrle Environmental, discusses how an advanced MBR system incorporating nanofiltration was successfully used to clean landfill leachate and establish a compact, sustainable solution.
TL;DR: In this article, the authors used a geocomposite drainage layer (GDL) for leachate recirculation in municipal solid waste (MSW) landfills.
Abstract: The key purpose of this study was to test the use of a permeable blanket made up of a geocomposite drainage layer (GDL) for leachate recirculation in municipal solid waste (MSW) landfills and to predict the observed leachate travel in the blanket using a numerical model. A 34 m long by 12 m wide permeable blanket made up of GDL was constructed at an active MSW landfill located in Michigan. Leachate was injected in the GDL using a perforated pipe placed centrally above the GDL along its length. Moisture content sensors, pressure transducers, thermistors, thermocouple sensors, and a vertical load sensor were embedded immediately below the GDL blanket to monitor the flow of injected leachate. After the blanket was covered with waste, leachate was injected into the blanket at rates ranging from 0.9 to 2.6 m3 ∕h per meter length of the blanket. Data collected from the embedded sensors indicated that the injected leachate traveled at rates ranging from 5 to 18 m∕h through the blanket depending upon the leachate...
TL;DR: Results demonstrate that in situ ammonia–nitrogen removal in decomposed aerated solid waste environments at the gas-phase oxygen concentrations and temperatures evaluated and the potential for simultaneous nitrification and denitrification in field-scale bioreactor landfills is significant due to the presence of both aerobic and anoxic areas.
Abstract: Waste acclimation and batch microcosm studies containing digested municipal solid waste were conducted at different temperatures (22, 35, and 45°C ) and gas-phase oxygen concentrations (0.7–100%, by volume) to provide guidance for field-scale implementation of in situ nitrogen removal processes. Results demonstrate that in situ ammonia–nitrogen is feasible in decomposed aerated solid waste environments at the gas-phase oxygen concentrations and temperatures evaluated and the potential for simultaneous nitrification and denitrification in field-scale bioreactor landfills is significant due to the presence of both aerobic and anoxic areas. Small amounts of oxygen were found sufficient for nitrification/ammonia removal to proceed, although removal rates increase with oxygen concentration. Laboratory results suggest field-scale implementation of in situ nitrogen removal occur in small dedicated treatment zones containing previously degraded waste (later in the life of a bioreactor landfill). Model simulations...
TL;DR: In this article, the authors present data on gas and leachate flow rates and levels obtained during a 600 day pumping trial on three retrofitted horizontal wells in a domestic waste landfill at Rainham, United Kingdom.
Abstract: This paper presents data on gas and leachate flow rates and leachate levels obtained during a 600 day pumping trial on three retrofitted horizontal wells in a domestic waste landfill at Rainham, United Kingdom. The changes in gas and leachate flow rate with time and atmospheric pressure, and the interaction between the two flows, are discussed. The spatial variability of the response of the leachate levels within the landfill is explored with reference to the anisotropy and heterogeneity of the permeability of the waste. It is shown that horizontal wells can be an effective means of controlling leachate heads near the base of a landfill, and that leachate levels must be measured using piezometers with a discrete response zone rather than fully screened observation wells if meaningful results are to be obtained. It is argued that the large amounts of gas pumped from the nominally saturated zone of the landfill must have come from the ongoing degradation of the waste within the zone of influence of the well.
TL;DR: The mathematical formulations in a one-dimensional compartment model of the biodegradation of organic landfill components are described, designed to switch between anaerobic and aerobic conditions, depending on the local oxygen concentration.
Patent•
18 Oct 2007
TL;DR: In this article, the landfill functions as a biological reactor (bioreactor), where water is added if or as necessary to achieve concentrations between about 20% and about 65% by weight, and desired microbial contaminant abatement action.
Abstract: Biochemical decomposition of undesirable gaseous contaminants, including nitrogen oxides, VOC's, carbon monoxide and sulfur oxides, and malodorous contaminants, is achieved by passing a gas stream through a managed landfill providing microbiological activity capable of degrading the contaminants. Gases suitable for treatment include fuel combustor exhaust, landfill gases, putrescent gases and the like. The landfill functions as a biological reactor (bioreactor), where water is added if or as necessary to achieve concentrations between about 20% and about 65% by weight, and desired microbial contaminant abatement action. By a permeation of the polluted gas through the landfill, there is a consumption of polluting gases by microorganisms present in the landfill. The process enables increased combustion of fuels, such as landfill gases, whose energy values are currently wasted or are not available due to emissions problems. The excess oxygen normally present in exhaust can advantageously result in additional oxidative waste consumption by microorganisms, yielding additional “air space” that is an economic bonus in extending landfill life and/or lessening landfill use.
TL;DR: A modified, ecologically sound waste treatment technique, where municipal solid waste is anaerobically treated in a lysimeter-scale landfill bioreactor with leachate recirculation to enhance organic degradation, demonstrates a substantial decrease in organic matter, and a clear decrease in nutrient concentrations especially ammonia over a period of 1 year with leaches.
Abstract: Emissions from landfills via leachate and gas are influenced by state and stability of the organic matter in the solid waste and the environmental conditions within the landfill. This paper describes a modified, ecologically sound waste treatment technique, where municipal solid waste is anaerobically treated in a lysimeter-scale landfill bioreactor with leachate recirculation to enhance organic degradation. The results demonstrate a substantial decrease in organic matter (BOD 99%, COD 88% and TOC 81%) and a clear decrease in nutrient concentrations especially ammonia (85%) over a period of 1 year with leachate recirculation.
TL;DR: In the Calgary biocell, which is a bioreactor landfill, real-time waste settlement data was collected during the filling of the cell and the average unit weight of the waste matrix and the compression index were calculated.
Abstract: The knowledge of the rate and amount of settlement is important for effective design and operation of bioreactor landfills. Accurate knowledge of settlement would allow estimation of air space, planning of construction sequence, design of both intermediate and final covers as well as planning for expansions. It is also essential for the design of piping systems used for the delivery of re-circulated leachate and landfill gas recovery. Though the majority of settlement takes after landfill closure over a number of years, considerable amount occurs during the filling and construction stages, which usually goes unnoticed. In the Calgary biocell, which is a bioreactor landfill, real-time waste settlement data was collected during the filling of the cell. The field data collected during the cell construction stage is presented in this manuscript. The settlement trend follows the waste filling operation. The data was analyzed and the average unit weight of the waste matrix and the compression index were calculated. These two parameters are can be used in models to predict early stage waste settlement. The compression index was calculated as 0.21 while the unit weight of waste was 5.6 kPa.