Landfill Surface Research Articles

Sampling method for the determination of methane emissions from landfill surfaces.

The first aim of this work is the definition and the study of a suitable sampling method for the measurement of landfill gas (LFG) emissions from landfill surfaces, since, up to now, there are no codified nor universally accepted sampling methods for this specific task. The studied sampling method is based on the use of a static hood. The research work involves a preliminary theoretical study for the hood design, experimental tests for the definition of the optimal sampling procedures, and simulations of the hood fluid-dynamics for the system validation. The second aim of this study is the investigation of the correlations between LFG emissions and meteorological conditions, whose identification would be very useful in terms of effective landfill management and pollution control. This involved a wide literature study for the selection of those parameters that seem to have an influence on LFG emission, and the collection of a great number of experimental data on a target site, which led to the conclusion that atmospheric pressure and soil humidity are the parameters that mostly affect LFG emissions.

Simulation of Contaminants Transport and Groundwater Flow for Basrah Landfill Site

groundwater aquifers is mostly effected from landfills due to intrusion of leachate from its base b. Active surface of landfills represents main source for leachate generation during rains or may be due to direct contact with groundwater, leading to the transport 5 pollutants from landfill which is intrudes to the aquifer under the landfill. In this research a 3-dimensional simulation models was constructed and calibrated to characterize groundwater flow and leachate pollution transport from Basrah province main landfill site. The selected study area is Al-Rafdhia landfill site, which is lie at Al-Zubair district (southern part of Iraq at Basrah). The model used in the simulation was Visual MODFLOW finite difference approach. All the required landfill and aquifer parameters, stressing and recharge estimates from field and laboratories works, Basrah climate data, observations, soil investigation reports and previous studies for the same region and then used in the model or adjusted by calibration. Six-month observation period was achieved to estimate the monthly state variables data such as heads and physical-chemical leachate and groundwater characteristics by measurement and sampling from the groundwater selected wells. Many soils and water samples were collected to know the aquifer characteristics and analyze the pollutants concentration values. Accordingly, the calibrated model was used to simulate the flow and pollution transport at current year and then used for prediction of future changes in water levels and landfill contaminant transport in the aquifer for planning period of 15 future years. The final simulation and predication results show that the landfill represent main source of contamination and the pollution would occur in the aquifer at high levels and with approximate lateral transporting of 285 m/year if the current state of solid waste disposal continue with increase of pumping from the aquifer from its current rate with future. The groundwater flow and concentration profiles for pollutants with time and spaces from the pollution sources was predicated and a 3-D representation were done for pollutants spreading for specific pollutants.

Mercury concentrations in environmental media at a hazardous solid waste landfill site and mercury emissions from the site

Mercury (Hg) concentrations in air, effluent water, landfill gas, leachate, groundwater, and soil at a hazardous solid waste landfill site in Korea were measured along with air–soil surface Hg exchange fluxes at the site. The concentrations and fluxes were considerably higher than have been found elsewhere in Korea. Gaseous Hg concentrations in the air peaked during the day, coinciding with Hg being released from the landfill surface. This suggests that air–soil exchange increased the Hg concentrations in the atmosphere. The air–soil exchange flux increased abruptly when solar radiation reached the soil surface. The Hg flux peaked about 3 h before the solar radiation peaked, possibly because reducible Hg was abundant at the soil surface. The Hg emission flux activation energy (E a) was low, indicating that the Hg species present and Hg–soil binding were probably not as important (because of the high Hg content of the soil) as in previous studies. The methylmercury to total Hg ratios in the discharged effluent, groundwater, and leachate was clearly higher than typically found in coastal water and freshwater, suggesting bacteria caused active methylation to occur under the reducing conditions in the anaerobic landfill. The results suggested that considerable amounts of Hg are probably transported from the landfill to nearby environmental media and that this will continue if waste with a high Hg content continues to be added to the landfill without being pretreated.

Toxicological assessment of closed municipal solid-waste landfill impact to the environment

The large number of municipal solid waste landfills in Lithuania poses a serious environmental threat to the quality of soil, surface and ground water. The physicochemical characteristics and toxicity of closed Panevėžys municipal solid-waste landfill leachate and its impact to soil and surface water were assessed. Landfill leachate is complex mixture of various inorganic and organic compounds. The toxicity of municipal solid waste landfill leachate and surface water was evaluated using bioassays with aquatic plants (Lemna minor L.) and microinvertebrates (Daphnia magna). The leachate was shown to be toxic to D. magna, reduced the growth and biomass of L. minor. The toxicity has been linked with ammonium and heavy metals content as the prime contributors to the toxicity.DOI: http://dx.doi.org/10.5755/j01.erem.72.4.16555

Bacteria Isolation from Landfill for Production of Industrial Enzymes for Waste Degradation

Background/Objectives: The purpose of this study is to isolate the potential bacteria for the production of industrial enzyme cellulose and xylanase for waste degradation. Methods/Statistical Analysis: The bacteria were isolated from three different sources (landfill surface, 10 cm depth soil and moist soil) collected from Sungai Ikan Landfill, Kuala Terengganu, Malaysia using serial dilution and spread plate technique. Primarily screening for the enzyme production was carried out. The bacteria isolates which shows a good clearing zone diameter in ranged 2.6-8.8 cm were selected for further quantitative screening for cellulase and xylanase production by performed submerged fermentation using Carboxymethyl Cellulose (CMC) and xylan as a substrate. Findings: A total of 130 potential bacteria were isolated on Nutrient Agar (NA). Only 50 and 30 of the isolates exhibited cellulase and xylanase, respectively, by showing clear zone on CMC and Xylan agar plates after stained with iodine dye. From the observation of the quantitative screening of enzyme activities, B6.2 isolate exhibited the highest cellulase activity (endoglucanase19.797 U/m Land FPase 7.384 U/mL) and M29 isolate exhibited the highest activity of xylanase (5399 U/mL). Overall, all isolates showed good cellulase and xylanse activity ranged between 0.491-19.797 U/mL and 2075-5399 U/mL, respectively. Application/Improvements: For future study, the enzyme produce will be used to degrade waste into fermentable sugars which used as a feedstock for bioethanol production.

Environmental assessment of contaminants in a downstream area of a landfill

Therefore, the evaluation of environmental risks associated with a landfill and the effect of landfill surface runoff was investigated. Soil samples were collected in the downstream area of the waste disposal site and their mineralogy was studied. An appraisal of the heavy metal contamination in the area was attempted. Top layers of sediments seem to interact with chemically modified surface runoff waters from the landfill. Heavy metals such as As and Pb were in significant concentrations in the sediments within a distance of 200 m from the site. Anions such as chloride, sulphate and phosphate adsorbed on clay minerals suggest the interaction of sediments with surface runoff from the waste disposal site. Inorganic parameters NH4 + and NO2 - in surface water samples are above or slightly below the guidelines recommended by EE and WHO. The results indicated that environmental monitoring of the landfill is considered essential.

Application of close-range aerial infrared thermography to detect landfill gas emissions: a case study

Monitoring waste disposal sites is important to check that the produced biogas, potentially explosive, is properly collected by the biogas extraction system of the landfill site and to evaluate the residual biogas flow escaping from upper surface of the landfill. As the biogas migrates to the surface, the soil through which it flows is expected to reach a higher temperature than the surrounding environment; thus, measuring the thermal footprint of the landfill soil surface could allow the detection of biogas leakages and spots suitable for the gas extraction. Close-range aerial infrared thermography is an innovative approach able to identify thermal anomalies with a good resolution over a large region of the landfill surface. A simple procedure to deduce the biogas flow rate emerging from the soil into the atmosphere, based on infrared thermography measurements, is presented. The approach has been applied to a case study concerning a large landfill located in Genoa (Italy). Aerial infrared photographs taken during different days and seasons showed the presence of thermal anomalies over regions along the peripheral boundary of the landfill still not interested in biogas extraction.

Application of portable gas detector in point and scanning method to estimate spatial distribution of methane emission in landfill

Methane from landfills contributes to global warming and can pose an explosion hazard. To minimize these effects emissions must be monitored. This study proposed application of portable gas detector (PGD) in point and scanning measurements to estimate spatial distribution of methane emissions in landfills. The aims of this study were to discover the advantages and disadvantages of point and scanning methods in measuring methane concentrations, discover spatial distribution of methane emissions, cognize the correlation between ambient methane concentration and methane flux, and estimate methane flux and emissions in landfills. This study was carried out in Tamangapa landfill, Makassar city-Indonesia. Measurement areas were divided into basic and expanded area. In the point method, PGD was held one meter above the landfill surface, whereas scanning method used a PGD with a data logger mounted on a wire drawn between two poles. Point method was efficient in time, only needed one person and eight minutes in measuring 400m2 areas, whereas scanning method could capture a lot of hot spots location and needed 20min. The results from basic area showed that ambient methane concentration and flux had a significant (p<0.01) positive correlation with R2=0.7109 and y=0.1544 x. This correlation equation was used to describe spatial distribution of methane emissions in the expanded area by using Kriging method. The average of estimated flux from scanning method was 71.2gm−2d−1 higher than 38.3gm−2d−1 from point method. Further, scanning method could capture the lower and higher value, which could be useful to evaluate and estimate the possible effects of the uncontrolled emissions in landfill.

매립지 표면의 메탄 발산량 실측을 위한 플럭스 챔버의 방법론적 비교와 최적화

매립지 표면의 메탄 발산량 실측을 위한 플럭스 챔버의 방법론적 비교와 최적화

Comparison of different approaches for the estimation of odour emissions from landfill surfaces

The aim of this study is related to the assessment of odour emissions from landfill surfaces. Up to now, there is not a widely accepted method to quantify odour emissions from this particular kind of source. Five different methods were developed and investigated. These methods can be considered as based on three distinct approaches, both experimental and computational. The first approach provides to use models for the estimation the landfill gas production, whereby the second and the third approach are based on direct measurement campaigns on the landfill surface: for the determination of the methane concentration or for the direct measurement of the odour concentration, respectively. The methods were then compared in terms of specific odour emission rates by referring to other literature data. Finally, dispersion modelling was applied in order to allow a further comparison of the resulting odour impacts with other olfactometric data from independent monitoring campaigns on the studied site.

Evaluation of an Odour Emission Factor (OEF) to estimate odour emissions from landfill surfaces

Emission factors are fundamental tools for air quality management. Odour Emission Factors (OEFs) can be developed in analogy with the emission factors defined for other chemical compounds, which relate the quantity of a pollutant released to the atmosphere to a given associated activity. Landfills typically represent a common source of odour complaint; for this reason, the development of specific OEFs allowing the estimation of odour emissions from this kind of source would be of great interest both for the landfill design and management. This study proposes an up-to-date methodology for the development of an OEF for the estimation of odour emissions from landfills, thereby focusing on the odour emissions related to the emissions of landfill gas (LFG) from the exhausted landfill surface. The proposed approach is an “indirect” approach based on the quantification of the LFG emissions from methane concentration measurements carried out on an Italian landfill. The Odour Emission Rate (OER) is then obtained by multiplying the emitted gas flow rate by the LFG odour concentration. The odour concentration of the LFG emitted through the landfill surface was estimated by means of an ad hoc correlation investigated between methane concentration and odour concentration. The OEF for the estimation of odour emissions from landfill surfaces was computed, considering the landfill surface as the activity index, as the product between the mean specific LFG flux emitted through the surface resulting from the experimental campaigns, equal to 0.39 l/m2/h, and its odour concentration, which was estimated to be equal to 105′000 eq. ouE/m3, thus giving an OEF of 0.011 ouE/m2/s. This value, which is considerably lower than those published in previous works, should be considered as an improved estimation based on the most recent developments of the research in the field of odour sampling on surface sources.

Use of CFD for static sampling hood design: An example for methane flux assessment on landfill surfaces

The work focuses on the principles for the design of a specific static hood and on the definition of an optimal sampling procedure for the assessment of landfill gas (LFG) surface emissions. This is carried out by means of computational fluid dynamics (CFD) simulations to investigate the fluid dynamics conditions of the hood. The study proves that understanding the fluid dynamic conditions is fundamental in order to understand the sampling results and correctly interpret the measured concentration values by relating them to a suitable LFG emission model, and therefore to estimate emission rates. For this reason, CFD is a useful tool for the design and evaluation of sampling systems, among others, to verify the fundamental hypotheses on which the mass balance for the sampling hood is defined. The procedure here discussed, which is specific for the case of the investigated landfill, can be generalized to be applied also to different scenarios, where hood sampling is involved.

Leachate and Surface Water Characterization and Heavy Metal Health Risk on Cockles in Kuala Selangor

Characterization of physicochemical parameters including concentration of heavy metals in landfill leachate, surface water and cockles (Anadara granosa) were analyzed in Kuala Selangor, Malaysia. The effects of location and seasonal variation of surface water and cockles were determined. In addition, the target hazard quotients (THQ) were calculated to determine the potential health risk. Heavy metals concentrations were analyzed by ICP-MS and the result were compared with the national permissible limit. There was a little variation in heavy metal concentration between location and season for surface water and cockles samples. THQ value was found lower for all heavy metal and shows no potential risk.

Short-term landfill methane emissions dependency on wind

Short-term (2–10h) variations of whole-landfill methane emissions have been observed in recent field studies using the tracer dilution method for emissions measurement. To investigate the cause of these variations, the tracer dilution method is applied using 1-min emissions measurements at Sandtown Landfill (Delaware, USA) for a 2-h measurement period. An atmospheric dispersion model is developed for this field test site, which is the first application of such modeling to evaluate atmospheric effects on gas plume transport from landfills. The model is used to examine three possible causes of observed temporal emissions variability: temporal variability of surface wind speed affecting whole landfill emissions, spatial variability of emissions due to local wind speed variations, and misaligned tracer gas release and methane emissions locations. At this site, atmospheric modeling indicates that variation in tracer dilution method emissions measurements may be caused by whole-landfill emissions variation with wind speed. Field data collected over the time period of the atmospheric model simulations corroborate this result: methane emissions are correlated with wind speed on the landfill surface with R2=0.51 for data 2.5m above ground, or R2=0.55 using data 85m above ground, with emissions increasing by up to a factor of 2 for an approximately 30% increase in wind speed. Although the atmospheric modeling and field test are conducted at a single landfill, the results suggest that wind-induced emissions may affect tracer dilution method emissions measurements at other landfills.

Permeability test and slope stability analysis of municipal solid waste in Jiangcungou Landfill, Shaanxi, China

ABSTRACTWith the rapid increase of city waste, landfills have become a major method to deals with municipal solid waste. Thus, the safety of landfills has become a valuable research topic. In this paper, Jiangcungou Landfill, located in Shaanxi, China, was investigated and its slope stability was analyzed. Laboratory tests were used to obtain permeability coefficients of municipal solid waste. Based on the results, the distribution of leachate and stability in the landfill was computed and analyzed. These results showed: the range of permeability coefficient was from 1.0 × 10–7 cm sec–1 to 6.0 × 10–3 cm sec–1 on basis of laboratory test and some parameters of similar landfills. Owing to the existence of intermediate cover layers in the landfill, the perched water level appeared in the landfill with heavy rain. Moreover, the waste was filled with leachate in the top layer, and the range of leachate level was from 2 m to 5 m in depth under the waste surface in other layers. The closer it gets to the surface of landfill, the higher the perched water level of leachate. It is indicated that the minimum safety factors were 1.516 and 0.958 for winter and summer, respectively. Additionally, the slope failure may occur in summer.Implications: The research of seepage and stability in landfills may provide a less costly way to reduce accidents. Landslides often occur in the Jiangcungou Landfill because of the high leachate level. Some measures should be implemented to reduce the leachate level. This paper investigated seepage and slope stability of landfills by numerical methods. These results may provide the basis for increasing stability of landfills.

Characterization of Aromatics at Working Surface of a Municipal Solid Waste Landfill

With the rapid urbanization and economic growth in China especially near 2 decades, the vast amount of municipal solid waste (MSW) were produced annually. Landfills are the predominant disposal sites for MSW in China, receiving more than 75% of the collected MSW every year. While the volume concentration is usually less than 1%, NMOCs are generally considered as the main source of the odorous problem at MSW landfills, because they include many compounds with very low odor thresholds. What’s more, aromatics is vital part of NMOCs for its toxic effect, which contains Benzene. The main objective of this study was to understand the comprehensive behavior of aromatics of landfill gas. In this work we present an integrated evaluation of working surface concentration distribution and emission rate of a municipal solid waste landfill. And in order to understand the transportation of aromatic, a new parameter was introduced to analyze this process. Thus, result shows, the fugitive emission of aromatics in the operating surface may need pay more attention. The highest average concentration for aromatics was found in autumn. Aromatic’s emission rate in winter was larger than autumn, the highest emission rate of aromatics toluene, 0.011g/m2/h. The B:T ratio in winter was significant higher that of other seasons.

Emissions of C&D refuse in landfills: A European case

A field study was developed in a new landfill for refuse from construction and demolition (C&D) material recovery plants of small size (4Ha.) in Europe, with the aim of evaluating the liquid and gas emissions in this type of facility at a large scale. It included characterization of the materials, monitoring leachate and gas quantity and composition. Besides thermometers, piezometers and sampling ports were placed in several points within the waste. This paper presents the data obtained for five years of the landfill life. The materials disposed were mainly made up of wood and concrete, similar to other C&D debris sites, but the amount of gypsum drywall (below 3% of the waste) was significantly smaller than other available studies, where percentages above 20% had been reported. Leachate contained typical C&D pollutants, such as different inorganic ions and metals, some of which exceeded other values reported in the literature (conductivity, ammonium, lead and arsenic). The small net precipitation in the area and the leachate recirculation into the landfill surface help explain these higher concentrations, thus highlighting the impact of liquid to solid (L/S) ratio on leachate characteristics. In contrast to previous studies, neither odor nuisances nor significant landfill gas over the surface were detected. However, gas samples taken from the landfill inside revealed sulfate reducing and methanogenic activity.

Modeling of H2S migration through landfill cover materials

The emission of H2S from landfills in the United States is an emergent problem because measured concentrations within the waste mass and in ambient air have been observed at potentially unsafe levels for on-site workers and at levels that can cause a nuisance and potentially deleterious health impacts to surrounding communities. Though recent research has provided data on H2S concentrations that may be observed at landfills, facility operators and landfill engineers have limited predictive tools to anticipate and plan for potentially harmful H2S emissions. A one-dimensional gas migration model was developed to assist engineers and practitioners better evaluate and predict potential emission levels of H2S based on four factors: concentration of H2S below the landfill surface (C0), advection velocity (v), H2S effective diffusion coefficient (D), and H2S adsorption coefficient of landfill cover soil (μ). Model simulations indicated that H2S migration into the atmosphere can be mitigated by reducing H2S diffusion and advection or using alternative cover soils with a high H2S adsorption coefficient. Laboratory column experiments were conducted to investigate the effects of the four parameters on H2S migration in cover soils and to calculate the adsorption coefficient of different cover materials. The model was validated by comparing results with laboratory column experiments. Based on the results, the laboratory column provides an effective way to estimate the H2S adsorption coefficient, which can then be incorporated into the developed model to predict the depth of cover soil required to reduce emitted H2S concentrations below a desired level.

Culturable psychrotolerant methanotrophic bacteria in landfill cover soil

Methanotrophs closely related to psychrotolerant members of the genera Methylobacter and Methylocella were identified in cultures enriched at 10@C from landfill cover soil samples collected in the period from April to November. Mesophilic methanotrophs of the genera Methylobacter and Methylosinus were found in cultures enriched at 20 degrees C from the same cover soil samples. A thermotolerant methanotroph related to Methylocaldum gracile was identified in the culture enriched at 40 degrees C from a sample collected in May (the temperature of the cover soil was 11.5-12.5 degrees C). In addition to methanotrophs, methylobacteria of the genera Methylotenera and Methylovorus and members of the genera Verrucomicrobium, Pseudomonas, Pseudoxanthomonas, Dokdonella, Candidatus Protochlamydia, and Thiorhodospira were also identified in the enrichment cultures. A methanotroph closely related to the psychrotolerant species Methylobacter tundripaludum (98% sequence identity of 16S r-RNA genes with the type strain SV96(T)) was isolated in pure culture. The introduction of a mixture of the methanotrophic enrichments, grown at 15 degrees C, into the landfill cover soil resulted in a decrease in methane emission from the landfill surface in autumn (October, November). The inoculum used was demonstrated to contain methanotrophs closely related to Methylobacter tundripaludum SV96.

Evaluation and remediation of organics, nutrients and heavy metals in landfill leachate – a case study in Beijing

Leachate pollution in landfill sites is a major source of environmental concern. This study evaluates organics, nutrients and heavy metals in a landfill site in Beijing, and introduces a method combining coagulation–flocculation with filtration for the advanced treatment of leachate. The results confirm that CODCr, TN, NH4+ − N, TP, Mn and As in leachate treated by an anaeobic–oxic biological method are unable to meet discharge or surface water quality standards. When treated with coagulation–flocculation combined with filtration under optimal conditions (cationic polyacrylamide dosage of 8.0 mg/L; polyaluminium chloride dosage of 350 mg/L; 0.4–0.6 mm ceramsite media in the filtration process), the residual NH4+− N, TN, Mn and As in the leachate meet the maximum allowed values for landfill leachate discharge or surface water quality standards in China; the exceptions are chemical oxygen demand and total phosphorus. Leachate treatment processes could be further strengthened or improved.