Search

Landfills have been identified as potential sources of heavy metal pollution of the environment. The municipal solid waste Łubna landfill is one of the largest landfills in Poland. Its impact on heavy metal pollution (Cd, Pb, Zn, Cu, and Cr) of groundwater, soil and plants has been thoroughly evaluated. Elevated levels of contamination have not been recorded in the vicinity of the landfill. The concentrations of heavy metals in soil from the vicinity of the landfill were similar to the geochemical background levels for the forest and farming soils of central Poland. The concentrations of heavy metals in European goldenrod (Solidago virgaurea L.) and grasses (Poaceae) did not exceed the baseline concentrations and did not indicate environmental pollution by heavy metals. The levels of the metal concentration in groundwater did not exceed the standards established for water intended for consumption.

Abstract: The large amounts of treated waste materials and the complex biological and physicochemical processes make the areas in the proximity of landfills vulnerable not only to emissions of potential toxic compounds but also to nuisance such as odor pollution. All these factors have a dramatic impact in the local environment producing environmental quality degradation. Most of the human health problems come from the landfill gas, from its non-methanic volatile organic compounds and from hazardous air pollutants. In addition several odorants are released during landfill operations and uncontrolled emissions. In this work we present an integrated risk assessment for emissions of hazard compounds and odor nuisance, to describe environmental quality in the landfill proximity. The study was based on sampling campaigns to acquire emission data for polychlorinated dibenzo-p-dioxins and dibenzofurans, dioxin-like polychlorobiphenyls, polycyclic aromatic hydrocarbons, benzene and vinyl chloride monomer and odor. All concentration values in the emissions from the landfill were measured and used in an air dispersion model to estimate maximum concentrations and depositions in correspondence to five sensitive receptors located in proximity of the landfill. Results for the different scenarios and cancer and non-cancer effects always showed risk estimates which were orders of magnitude below those accepted from the main international agencies (WHO, US EPA). Odor pollution was significant for a limited downwind area near the landfill appearing to be a significant risk factor of the damage to the local environment. [Copyright &y& Elsevier]

This paper provides information about biodegradability of biodegradable/degradable materials advertised as 100%-degradable or certified as compostable in a municipal solid-waste landfill. It describes a 12- month experiment with five samples that took place in a landfill. The results, demonstrated that the polyethylene sample with the additive (samples 1) and sample labelled as 100% degradable (sample 2) had not decomposed, and no physical changes had occurred; however, their color had changed slightly. Samples 2 and 3 (certified as compostable) did not decompose. However, sample 3 exhibited minor disruptions. Sample 5 was a control reference sample to confirm that the conditions of decomposition were suitable during the experiment, which was the case. The cellulose filter paper (sample 5) degraded after 8 months, implying that it was fully biodegraded (100%) and that the conditions required for biodegradation to occur in a sampling environment were present. [ABSTRACT FROM AUTHOR]

Copyright of Ochrona Srodowiska i Zasobów Naturalnych is the property of Sciendo and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Highlights: [•] We established a comprehensive LCI method for landfill construction and operation. [•] We reported the consumption of materials and energy in a generic Chinese landfill. [•] The contribution of C&O to the impacts of total landfilling is not negligible. [•] Non-toxic and toxic impacts are attributed to diesel and mineral usage, respectively. [•] Replacing minerals with synthetic materials is effective in mitigating impacts. [Copyright &y& Elsevier]

Copyright of Ochrona Srodowiska i Zasobów Naturalnych is the property of Sciendo and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Nitrogen pollutants such as ammonia and nitrates cause soil and groundwater contamination at municipal solid waste landfill (MSWL) sites due to leachate leakage. Here, the migration of nitrogen pollutants in the vadose zone of the red bed (VZRB) at a MSWL site was studied by static adsorption batch experiments and one-dimensional simulated migration experiments. The results indicated that the soil in the red bed did not adsorb nitrates. Chemical adsorption and monolayer adsorption of the soil played dominant roles during ammonia adsorption in the VZRB, which was best fitted by the pseudo-second-order kinetic equation (R N H 4 + 2 = 0.99) and the Langmuir model. The ammonia adsorption capacity of the soil was the highest (Q m = 2.041 mg·g−1) at 318 K. It was due to the endothermic and non-spontaneous chemical adsorption of ammonia, whose enthalpy change (ΔH) reached 20.995 kJ·mol−1 and Gibbs free energy ranged from 8.469 to 8.706 kJ·mol−1. Chloride penetration tests indicated that the diffusion coefficient and migration speed reached 0.0515 cm2·h−1 and 0.0833 cm·h−1, respectively, in the clay layer under the MSWL sites. The average hysteresis diffusion coefficients of ammonia in the simulated soil columns leached by ammonium chloride solution (SSCAC) and by the leachate from MSWL (SSCL) were 1.129 and 1.400, respectively. After the leaching experiments, the clay pore structure was saturated, and the specific surface area decreased. The absorption peak intensities of clay functional groups, including carboxyl, alkyne, and hydroxyl groups, were reduced. The ammonia content in the soil of SSCAC decreased from the top (14.51 mg·kg−1) to the bottom (3.14 mg·kg−1) and in the SSCL from 24.96 mg·kg−1 to 5.05 mg·kg−1, respectively. Thus, the impermeable clay layer and VZRB helped in retardation of ammonia leakage from MSWL sites. This was due to the blockage of seepage, ammonia mechanical filtration, ammonia monolayer chemical adsorption, and the reaction between the functional groups and ammonia in the VZRB underneath the MSWL sites. [Display omitted] • The loamy soil in the VZRB had high ammonia adsorption capacity. • The ammonia adsorption and desorption were followed the pseudo-second-order kinetic. • The ammonia adsorption was endothermic, non-spontaneous chemical process. • Mechanical filtration, adsorption and biofilms blocked the nitrogen migration. [ABSTRACT FROM AUTHOR]

The paper deals with studying the process of neutralization of contaminated filtrate, accumulated in a sump at municipal solid waste landfill. The main polluting components are phenols and ferrous ions. The proposed neutralization method consists of four stages and involves alignment of the sump bottom, filling the neutralizing layer, filling the absorbent layer, filling the pressing layer. In the process of water purification, its components are under control. Calcium oxide and slag are used as neutralizing mixture, and layered double hydroxides - as sorbent. The mixture is put alternatively, 1 cm of mixture by 1 cm of slag. For implementation of the neutralization method and precipitation of required amount of iron, 86.8 tons of calcium oxide and 347.1 tons of slag are needed. The total amount of layered double hydroxides, required for complete adsorption of phenols, constitutes 70 tons. [ABSTRACT FROM AUTHOR]

A numerical model is used to estimate the service life and clogging of gravel leachate drainage layers with a filter separator layer, such as those used in municipal solid waste landfills. A filter separator layer between the waste and the drainage layer is shown to reduce the leachate strength entering the gravel drainage layer and to extend the time that it takes to clog the drainage layer to the point when the leachate level exceeds the maximum design value (the service life). The filter layer is shown to have a far more significant effect in extending the service life when pea gravel () is used in the drainage layer, and less effect when coarse gravel () is used in the cases examined, although most of the benefit of a filter separator layer was achieved by using a 3-mm-thick needle-punched nonwoven geotextile. This geotextile may be sufficient for many practical purposes that are similar to those examined. The results from modeling leachate collection systems with filter separator layers subjected to both constant and variable leachate strength show that the characteristics of the leachate entering the drainage layer can substantially affect the service life of the drainage layer, and that high-strength leachate entering the systems for a limited time early in the life (acid phase) of a landfill can greatly reduce the service life of the leachate drainage layer. [ABSTRACT FROM AUTHOR]

The quantitative effects of three operational factors, that is initial compaction, decomposition condition and leachate level, on municipal solid waste (MSW) landfill settlement and storage capacity are investigated in this article via consideration of a hypothetical case. The implemented model for calculating landfill compression displacement is able to consider decreases in compressibility induced by biological decomposition and load dependence of decomposition compression for the MSW. According to the investigation, a significant increase in storage capacity can be achieved by intensive initial compaction, adjustment of decomposition condition and lowering of leachate levels. The quantitative investigation presented aims to encourage landfill operators to improve management to enhance storage capacity. Furthermore, improving initial compaction and creating a preferential decomposition condition can also significantly reduce operational and post-closure settlements, respectively, which helps protect leachate and gas management infrastructure and monitoring equipment in modern landfills. [ABSTRACT FROM PUBLISHER]

The landfill is a dynamic object, in which occurs to mineralization of wastes and their correlative reactions. Stored wastes undergo through many physical, chemical and biological changes. The rate of these processes increases with temperature and moisture up to a certain upper limit. The result of these activities is leachate and landfill gas. Predicting quantity of leachate is a critical parameter in the design of landfill construction. Created amount of leachate influences the way how to capture, collect and process the leachate. In resolving that issue, it's important to design optimal water regime of landfill order to ensure the elimination of potential environmental pollution. [ABSTRACT FROM AUTHOR]

This manuscript develops a model for assessing the time and space variations in unit weight of traditional municipal solid waste (MSW) landfills. The model considers the variations of unit weight caused by deformation of the waste matrix and degradation of the organic portion. Deformation of the waste matrix includes both short-term effects, resulting from mechanical strain during the filling period, and long-term effects, resulting from superposition of waste skeleton creep and waste degradation. Mass loss, caused by waste degradation, not only affects the stress level within the waste column, but also induces large and long-term deformation. Degradation-induced deformation is caused by the local collapse of the solid matrix weakened by mass loss. Considering that the correlation between mass loss and waste deformation is locally erratic and hard to define, a smooth time–strain curve (represented by Kelvin viscoelastic model) is used to describe approximately the overall long-term deformation. The analytical formulation for unit weight is obtained in Laplace transform domain and can be used to simulate spatial and temporal variations of waste unit weight. Unit weight profiles obtained at four MSW landfills using the proposed model agree well with measurements from in situ large-scale unit weight tests. Evolution of unit weight profiles indicates that there is no monotonous varying trend for unit weight along the whole depth of the landfill. Density first increases and then decreases to a stable value in the lower portion, whereas the opposite occurs in the upper portion. Whether unit weight increases or decreases depends on the competition between matrix deformation and degradation processes. [ABSTRACT FROM PUBLISHER]

Anaerobic landfills are the type most commonly adopted in the majority of developing countries. However, environmental problems generated from anaerobic-type landfills such as high concentrations of organic carbon (TOC) and nitrogen (TN) in leachate, a long stabilization period, and a heavy generation of greenhouse gases (GHG) are attracting more and more attentions. The aerobic-anaerobic method was initially touted as a new landfill method that incorporated the advantages of aerobic-type landfill, while at the same time lowering operational costs. Air is injected into the solid waste layer of an anaerobic-type landfill at the appropriate stabilization phase and depth to create an aerobic atmosphere in the solid waste layer, which enhances the decomposition of TOC and TN. During the decomposition of TOC, it can be expected that aerobic decomposition will restrain the emission of methane gas, as well as achieve an earlier stabilization of landfilled solid waste. The objective of this study is to clarify the air injection conditions that are optimal to improve leachate quality, restrain GHG emission, and enhance landfilled solid waste stabilization. Three large lysimeters, measuring 3 m in height, were constructed for the execution of experiments under different air injection conditions, and the resultant leachate quality and gas composition in the lysimeters were examined. In addition, a one-dimensional landfill model was developed and the influences of air injection conditions on leachate quality, landfill gas generation and stabilization of landfilled solid waste were estimated by numerical simulation. As a result, it was clarified that air injection at the deepest depth, which is 2.5 m depth in this study, is best for decreasing TOC discharge and GHG emission. [ABSTRACT FROM AUTHOR]

Compaction characteristics of municipal solid waste (MSW) were determined in the laboratory and in the field as a function of moisture content, compactive effort, and seasonal effects. Laboratory tests were conducted on manufactured wastes using modified and 4X modified efforts. Field tests were conducted at a MSW landfill in Michigan on incoming wastes without modifications to size, shape, or composition, using typical operational compaction equipment and procedures. Field tests generally included higher efforts and resulted in higher unit weights at higher water contents than the laboratory tests. Moisture addition to wastes in the field was more effective in winter than in summer due to dry initial conditions and potential thawing and softening of wastes. The measured parameters in the laboratory were γdmax-mod=5.2 kN/m3, wopt-mod=65%, γdmax-4×mod=6.0 kN/m3, and wopt-4×mod=56%; in the field with effort were γdmax-low=5.7 kN/m3, wopt-low=70%; γdmax-high=8.2 kN/m3, and wopt-high=73%; and in the field with season were γdmax-cold=8.2 kN/m3, wcold=79.5%, γdmax-warm=6.1 kN/m3, and wwarm=70.5%. Soil compaction theory was reasonably applicable to wastes with the exception that the Gs of waste solids increased with compactive effort resulting in steep degree of saturation curves and low change in wopt between efforts. Moisture addition to wastes during compaction increased the workability, the unit weight, and the amount of incoming wastes disposed, and reduced the compaction time. The combined effects have significant environmental and economic implications for landfill operations. [ABSTRACT FROM AUTHOR]

Long-term spatial and temporal variations in temperatures have been investigated in covers, wastes, and liners at four municipal solid waste landfills located in different climatic regions: Alaska, British Columbia, Michigan, and New Mexico. Temperatures were measured in wastes with a broad range of ages from newly placed to old (up to 40 years). The characteristic shape of waste temperature versus depth relationships consisted of a convex temperature profile with maximum temperatures observed at central locations within the middle third fraction of the depth of the waste mass. Lower temperatures were observed above and below this central zone, with seasonal fluctuations occurring near the surface and steady and elevated values (above mean annual earth temperature) near the base of the landfills. Heat gain and long-term temperatures were directly affected by placement temperatures. Sustained concave temperature profiles were observed for winter waste placement. The highest heat gain and resulting high temperatures were observed in Michigan followed by British Columbia, New Mexico, and Alaska. The high heat gain in Michigan was attributed to coupled precipitation/moisture content and waste density. The time-averaged waste temperature ranges were 0.9–33.0, 14.4–49.2, 14.8–55.6, and 20.5–33.6°C in Alaska, British Columbia, Michigan, and New Mexico, respectively. Temperature increases occurred rapidly (over multiple years) in British Columbia and then dissipated for tens of years. Longer periods of temperature increase were observed at the other sites. Temperatures, temperature increases, and heat gain were higher during anaerobic decomposition of wastes than aerobic decomposition. A parametric study indicated that use of insulating materials over covers decreased temperature variations compared to uninsulated conditions for prevention of frost penetration or desiccation and for optimum methane oxidation. Overall, thermal regime of landfills is controlled by climatic and operational conditions. [ABSTRACT FROM AUTHOR]

Abstract: Active gas control systems are commonly used in municipal solid waste (MSW) landfills and the design of such systems requires thorough understanding of the gas flow pattern. A model is developed to predict the two-dimensional radial transient gas flow to a vertical gas extraction well in deformable MSW landfills. Variations of gas storage include time-dependent compression of the refuse, dissolution of gas components and porosity enlargement due to organic matter degradation. Mechanical compression of solid skeleton is coupled with gas pressure using K–H rheological model which is capable of reproduce the evolution of settlement for MSW landfills. The new analytical solution obtained in Laplace transform domain can be used to determine excess gas pressure fields, gas fluxes in the well and through the top cover as well as landfill settlements. The solution is validated by comparison with field measurements and numerical simulations. It demonstrates that the gas storage variation term becomes predominant only during early times. Long-term gas flow is controlled by the gas generation rate and the quasi-steady solution is valid. Parametric studies indicate that the solution given in this paper is useful for the prediction of gas fluxes, for the choice of the optimum spacing between wells, and for the determination of the final cover properties as well as appropriate vacuum pressure imposed in the extraction well. [Copyright &y& Elsevier]

Abstract: An air pollution modeling study was conducted to investigate the odorous effects of volatile organic compounds (VOCs) emissions from a sanitary landfill area on ambient air quality. The atmospheric dispersion of hydrogen sulfide (H2S) and 22 VOCs was modeled. Industrial Source Complex v3 Short Term (ISCST3) model was used to estimate hourly concentrations of odorous VOCs over the nearest residential area. Odor thresholds of VOCs of interest were also found in the literature. Results showed that short-term averages of three odorous VOCs, namely ethyl mercaptan, methyl mercaptan and hydrogen sulfide, exceeded their odor thresholds, which are reported to be 0.022, 0.138 and 11.1μg/m3, respectively, at several points within the domain. Their highest concentrations within Gokturk County were estimated to be 0.09387μg/m3 for ethyl mercaptan, 0.07934μg/m3 for methyl mercaptan and 6.315μg/m3 for hydrogen sulfide. Short-term model results revealed the occasional odor problems being reported for Gokturk County. Hourly concentrations were used to obtain frequencies of odor episodes in Gokturk County via a probability analysis. The results showed that ethyl mercaptan concentrations did not exceed its odor threshold during more than 8.84% of the time. Similarly, the maximum odor episode frequencies for methyl mercaptan and hydrogen sulfide were 0.98% and 0.34% of the time, respectively. [Copyright &y& Elsevier]

Municipal solid waste landfills are the significant anthropogenic sources of N2O due to the cooxidation of ammonia by methane-oxidizing bacteria in cover soils. Such bacteria could be developed through CH4 fumigation, as evidenced by both laboratory incubation and field measurement. During a 10-day incubation with leachate addition, the average N2O fluxes in the soil samples, collected from the three selected landfill covers, were multiplied by 1.75 (p < 0.01), 3.56 (p < 0.01), and 2.12 (p < 0.01) from the soil samples preincubated with 5% CH4 for three months when compared with the control, respectively. Among the three selected landfill sites, N2O fluxes in two landfill sites were significantly correlated with the variations of the CH4 emissions without landfill gas recovery (p < 0.001). N2O fluxes were also elevated by the increase of the CH4 emissions with landfill gas recovery in another landfill site (p > 0.05). The annual average N2O flux was 176 ± 566 μg N2O–N m−2 h−1 (p < 0.01) from sandy soil–covered landfill site, which was 72% (p < 0.05) and 173% (p < 0.01) lower than the other two clay soil covered landfill sites, respectively. The magnitude order of N2O emissions in three landfill sites was also coincident by the results of laboratory incubation, suggesting the sandy soil cover could mitigate landfill N2O emissions. [Copyright &y& Elsevier]

Abstract: This study presents the field investigations into the effects of cover soils and leachate subsurface irrigation on N2O emissions from municipal solid waste landfills. Landfill Site A and Site B, covered with carefully chosen infertile soils, were selected to monitor their diurnal and seasonal variations of N2O emissions. The annual average N2O flux was 469±796μgN2O-Nm−2 h−1 in Site B with leachate subsurface irrigation, three times that of Site A without leachate irrigation. When an additional soil containing lower contents of carbon and nitrogen was introduced to cover part of Site B, its N2O fluxes decreased by 1–2 orders of magnitude compared with the left area of Site B. This suggested that carefully selected cover soils could substantially reduce N2O emissions even under leachate subsurface irrigation. Statistical analysis proved that the availabilities of soil moisture and mineralized nitrogen were the key parameters controlling landfill N2O emissions. [Copyright &y& Elsevier]

CH4 emissions and leachate disposal are recognized as the two major concerns in municipal solid waste (MSW) landfills. Recently, leachate recirculation was attempted to accelerate land-filled waste biodegradation and thus enhanced landfill gas generation. Leachate irrigation was also conducted for volume reduction effectively. Nevertheless, the impacts of leachate recirculation and irrigation on landfill CH4 emissions have not been previously reported. A field investigation of landfill CH4 emissions was conducted on selected sandy soil cover with leachate recirculation and subsurface irrigation based on whole year around measurement. The average CH4 fluxes were 311±903, 207±516, and 565±1460 CH4 m−2 h−1 from site A without leachate recirculation and subsurface irrigation, lift B2 with leachate subsurface irrigation, and lift B1 with both leachate recirculation and subsurface irrigation, respectively. Both gas recovery and cover soil oxidation minimized CH4 emissions efficiently, while the later might be more pronounced when the location was more than 5m away from gas recovery well. After covered by additional clay soil layer, CH4 fluxes dropped by approximately 35 times in the following three seasons compared to the previous three seasons in lift B2. The diurnal peaks of CH4 fluxes occurred mostly followed with air or soil temperature in the daytimes. The measured CH4 fluxes were much lower than those of documented data from the landfills, indicating that the influences of leachate recirculation and subsurface irrigation on landfill CH4 emissions might be minimized with the help of a well-designed sandy soil cover. Landfill cover composed of two soil layers (clay soil underneath and sandy soil above) is suggested as a low-cost and effective alternative to minimize CH4 emissions. [Copyright &y& Elsevier]

Abstract: Municipal solid waste landfills emit nitrous oxide (N2O) gas. Assuming that the soil cover is the primary N2O source from landfills, this study tested, during a four-year project, the hypothesis that the proper use of chosen soils with fine texture minimizes N2O emissions. A full-scale sanitary landfill, a full-scale bioreactor landfill and a cell planted with Nerium indicum or Festuca arundinacea Schreb, at the Hangzhou Tianziling landfill in Hangzhou City were the test sites. The N2O emission rates from all test sites were considerably lower than those reported in the published reports. Specifically, the N2O emission rate was dependent on soil water content and nitrate concentrations in the cover soil. The effects of leachate recirculation and irrigation were minimal. Properly chosen cover soils applied to the landfills reduced N2O flux. [Copyright &y& Elsevier]

The article presents abstracts of several studies on environmental geochemistry. Some of the abstracts presented include "Biogeochemical Cycling of Nutrients in Karstic Catchments, Southwestern China: Linkages to Changes of Eco-Environments," by Congqiang Liu and "Emerging Organic Contamination in China," by Guibin Jiang and colleagues.

In this paper, the tritium levels in the leachates and methane gas condensates which have occurred at 13 sanitary landfills of municipal solid wastes (MSW) are investigated and repotted. During the 6 months investigation period, the mean tritium concentrations of the raw leachates were distributed from 17 to 1,196 TU. They corresponded to several scores or hundreds higher tritium levels than that of the normal environmental level except for two cases. High tritium levels were also detected in the effluents of the leachate treatment facilities. Generally, the tritium existed in the dissolving fraction of the leachate but for some cases about 10% of the total tritium content was present as colloidal particles of over 0.45 µm in size. In general, the relationship between the tritium and other contaminants in the raw leachate was low, but it was relatively high between the tritium and TOC. Thus, it is predicted that the dissolving state of the tritium in the leachates would be affected by the tritium sources of the tipped wastes in a MSW. [ABSTRACT FROM AUTHOR]