Municipal Waste Landfill Research Articles

Conceptual design and quantification of phosphorus flows and balances at the country scale: The case of France

Global biogeochemical cycles have been deeply modified by human activities in recent decades. But detailed studies analyzing the influence of current economic and social organizations on global biogeochemical cycles within a system perspective are still required. Country level offers a relevant scale for assessing nutrient management and identifying key driving forces and possible leaks in the nutrient cycle. Conceptual modeling helps to quantify nutrient flows within the country and we developed such an approach for France. France is a typical Western European country with intensive agriculture, trade and an affluent diet, all of which may increase internal and external P flows. Phosphorus (P) was taken as a case study because phosphate rock is a non‐renewable resource which future availability is becoming increasingly bleak. A conceptual model of major P flows at the country scale was designed. France was divided into agriculture, industry, domestic, import and export sectors, and each of these sectors was further divided into compartments. A total of 25 internal and eight external P flows were identified and quantified on a yearly basis for a period of 16 years (from 1990 to 2006) in order to understand long‐term P flows. All the P flows were quantified using the substance flow analysis principle. The results showed that the industrial sector remained the largest contributor to P flows in France, followed by the agriculture and domestic sectors. Soil P balance was positive. However, a positive P balance of 18 kg P ha−1 in 1990 was reduced to 4 kg P ha−1 in 2006, mainly due to the reduced application of inorganic P fertilizer. The overall country scale P balance was positive, whereas half of this additional P was lost to the environment mainly through the landfilling of municipal and industrial waste, disposal of treated wastewater from which P was partially removed, and P losses from agricultural soils though erosion and leaching. Consequences for global P resources and soil and water compartments are discussed. Some opportunities to more effectively close the P cycle in France by both improving the intensity of P recycling and decreasing losses are quantified.

Modelling of thermally induced desiccation of geosynthetic clay liners in double composite liner systems

Double composite liner systems (DCLSs) for municipal or hazardous waste landfills often include geomembranes (GMBs) and geosynthetic clay liners (GCLs). Heat generated within such landfills due to exothermic degradation of organic matter or hydration of incinerator ash creates thermal gradients across the liner. These thermal gradients have the potential to induce a movement of moisture and create a risk of desiccation of the mineral component of the GCLs. This paper presents the results of a simulation of moisture redistribution and discusses the potential for desiccation of GCLs in DCLSs when subjected to thermal gradients using a numerical model developed by Zhou and Rowe (2003). The results from a series of laboratory experiments previously reported by the authors (Azad et al., 2011) are compared with model predictions. Two alternative soil water characteristic curves (SWCC), proposed by van Genuchten (1980) and Fredlund and Xing (1994), are implemented and their effects on the model’s accuracy assessed. The original model is found to predict reasonably well water distribution and the likelihood of thermal desiccation of the GCL.

The microbial ecology of anaerobic cellulose degradation in municipal waste landfill sites: evidence of a role for fibrobacters

Cellulose is reputedly the most abundant organic polymer in the biosphere, yet despite the fundamental role of cellulolytic microorganisms in global carbon cycling and as potential sources of novel enzymes for biotechnology, their identity and ecology is not well established. Cellulose is a major component of landfill waste and its degradation is therefore a key feature of the anaerobic microbial decomposition process. Here, we targeted a number of taxa containing known cellulolytic anaerobes (members of the bacterial genus Fibrobacter, lineages of Clostridium clusters I, III, IV and XIV, and anaerobic fungi of the Neocallimastigales) in landfill leachate and colonized cellulose 'baits' via PCR and quantitative PCR (qPCR). Fibrobacter spp. and Clostridium clusters III, IV and XIV were detected in almost all leachate samples and cluster III and XIV clostridia were the most abundant (1-6% and 1-17% of total bacterial 16S rRNA gene copies respectively). Two landfill leachate microcosms were constructed to specifically assess those microbial communities that colonize and degrade cellulose substrates in situ. Scanning electron microscopy (SEM) of colonized cotton revealed extensive cellulose degradation in one microcosm, and Fibrobacter spp. and Clostridium cluster III represented 29% and 17%, respectively, of total bacterial 16S rRNA gene copies in the biofilm. Visible cellulose degradation was not observed in the second microcosm, and this correlated with negligible relative abundances of Clostridium cluster III and Fibrobacter spp. (≤ 0.1%), providing the first evidence that the novel fibrobacters recently detected in landfill sites and other non-gut environments colonize and degrade cellulose substrates in situ.

Quantifying the Benefits of Using Flue Gas Desulfurization Gypsum in Sustainable Wallboard Production

Electric utilities produce more than 11.2 Mt of flue gas desulfurization (FGD) gypsum annually. Approximately 7.5 Mt is used in wallboard production. This article examines the environmental and cost benefits associated with replacement of natural gypsum in wallboard with FGD gypsum. A life-cycle analysis program was used to quantify the benefits of using FGD gypsum from electric power production in wallboard construction. Comparisons were made between energy consumption, water use, and greenhouse gas (GHG) emissions associated with obtaining and processing virgin gypsum material and those with FGD gypsum. The added impact of disposing of the unused FGD gypsum in landfills was also considered using life-cycle inventory for data generated from construction, operation, and maintenance costs for Subtitle D (nonhazardous municipal solid waste) landfills. Based on 2007 consumption data, the use of FGD gypsum in wallboard manufacture and concomitant avoided landfilling of unused FGD gypsum reduced energy consumption by 1200 TJ, water consumption by 18 GL, GHG emissions by 83 kt CO~2~e, and had a cost savings of DOLLAR49 to DOLLAR64 million dollars. The 2007 reduction in energy consumption from using FGD gypsum in wallboard is commensurate with the annual energy use of 11,800 homes, 58% of the annual domestic water use in Nevada, and the removal of 11,400 automobiles from the roadway.

REDUCING ENVIRONMENTAL RISK OF LANDFILLS: LEACHATE TREATMENT BY REVERSE OSMOSIS

Sanitary landfilling is nowadays the most common way to eliminate municipal solid wastes, although waste management hierarchy considers landfilling as a last option. The resultant leachate produced due to waste transformation and rainfall can be identified by specific characteristics and variables, corresponding to high-strength wastewaters, which generate impacts and risks in the environment. This situation imposes stringently leachate treatment by appropriate and efficient methods and processes. This research analyzes the performance of a municipal waste landfill leachate treatment system applying a membrane process - reverse osmosis (RO), for almost a year of operation. The system equipped with disc-tube (DT) membrane modules, and located in the sanitary landfill of the city of Iasi, Romania includes two stages: LEACHATE stage and PERMEATE stage, preceded by a pre-treatment module consisting of sand and cartridge filters. A storage system is included in the flow-sheet, for cleaning agents and various chemicals. Pumping stations provide the necessary operating pressure in the system. A removal efficiency of contaminants (COD, NH4+, electrical conductivity etc.) exceeding 90% was achieved. Any variation in permeate flux (14-22 L/m2h) and separation efficiency (94-100%) was due to increasing osmotic pressure and fouling, scaling and polarization of concentration. The RO process demonstrated a high rejection rate for both organic and inorganic contaminants dissolved in the leachate, together with a high flexibility alongside the changes in the leachate composition, depending on pressure, temperature, pH feeding flow rate of leachate.

Biological treatment and ozone oxidation: Integration or coupling?

Wastewaters generated by many economically relevant industrial activities contain recalcitrant organic compounds which pass unaltered through biological stage of the treatment plant making it difficult to meet the discharge limits currently in force. Therefore, an additional treatment is usually required to remove these compounds. In this study, the application of ozonation together with biological treatment was investigated. In particular, the effectiveness of biological degradation followed by or integrated with ozonation for treating the effluents produced by three environmentally relevant activities (i.e., leather and textile processing and municipal waste landfilling) are compared in the present paper. The results show that biological treatment followed by ozonation does not guarantee depurative levels sufficient for discharge for landfill leachates and tannery wastewater. On the contrary, thanks to the synergy between biological degradation and ozonation, integrated treatment significantly improves the process performance for all the investigated wastewaters, thus allowing the discharge limits to be met.

Environmental assessment and sustainable management options of leachate and landfill gas treatment in Estonian municipal waste landfills

PurposeThe purpose of this paper is to compare various landfill gas (LFG) and leachate treatment technologies in a life‐cycle perspective.Design/methodology/approachSince a landfill causes emissions for a very long‐time period, life‐cycle‐based environmental assessment was carried out to compare different technological options for sustainable leachate treatment and LFG collection and utilization. WAMPS, the life‐cycle assessment (LCA) model for waste management planning, was used for the environmental assessment of selected leachate and LFG treatment technologies.FindingsResults of both direct measurements in the studied landfills and LCA support the fact that leachate treatment with reverse osmosis has the best environmental performance compared to aerobic‐activated sludge treatment. Recently, the collection efficiency of LFG in the studied landfills is relatively low. In order to improve the overall environmental performance of LFG management the gas collection rate should be improved. LFG utilisation for energy recovery is an essential part of the system. The results of the study show that the avoided impacts of energy recovery can be even greater than direct impacts of greenhouse gas emissions from landfills. Therefore, measures which combine LFG collection with energy generation should be preferred to treatment in flare.Research limitations/implicationsIt should be noted that the results of this study do not express the total environmental impacts of the entire landfill system, but only the eutrophicating impacts and global warming related to the studied leachate and LFG management options. Therefore, it is recommended that further LCAs investigate also other relevant impact categories.Practical implicationsThe results of LCA modelling show that it is important to ensure the highest collection and treatment efficiency of leachate and LFG, since poor capture compromises the overall environmental performance of a landfill.Originality/valueThe paper provides a site‐specific data on sustainable leachate and LFG management in selected Estonian conventional municipal solid waste landfills. As such, the paper contributes to the development of the regional reference input data for LCA in waste management.

Study of the VOC emissions from a municipal solid waste storage pilot-scale cell: Comparison with biogases from municipal waste landfill site

The emission of volatile organic compounds (VOCs) from municipal solid waste stored in a pilot-scale cell containing 6.4 tonnes of waste (storage facility which is left open during the first period (40 days) and then closed with recirculation of leachates during a second period (100 days)) was followed by dynamic sampling on activated carbon and analysed by GC–MS after solvent extraction. This was done in order to know the VOC emissions before the installation of a methanogenesis process for the entire waste mass. The results, expressed in reference to toluene, were exploited during the whole study on all the analyzable VOCs: alcohols, ketones and esters, alkanes, benzenic and cyclic compounds, chlorinated compounds, terpene, and organic sulphides. The results of this study on the pilot-scale cell are then compared with those concerning three biogases from a municipal waste landfill: biogas (1) coming from waste cells being filled or recently closed, biogas (2) from all the waste storage cells on site, and biogas (3) which is a residual gas from old storage cells without aspiration of the gas. The analysis of the results obtained revealed: (i) a high emission of VOCs, principally alcohols, ketones and esters during the acidogenesis; (ii) a decrease in the alkane content and an increase in the terpene content were observed in the VOCs emitted during the production of methane; (iii) the production of heavier alkanes and an increase in the average number of carbon atoms per molecule of alkane with the progression of the stabilisation/maturation process were also observed. Previous studies have concentrated almost on the analysis of biogases from landfills. Our research aimed at gaining a more complete understanding of the decomposition/degradation of municipal solid waste by measuring the VOCs emitted from the very start of the landfill process i.e. during the acidogenesis and acetogenesis phases.

Persistent Organic Pollutants (POPs) in leachates from municipal landfills

The leachates from six municipal waste landfills, located in South-eastern Poland, were studied for the presence of major, Persistent Organic Pollutants (POPs) – PAHs, Polychlorinated Dibenzo-p-dioxins (PCDDs)/Polychlorinated Dibenzofurans (PCDFs), Polychlorinated Dibenzothiophenes (PCDTs) and Polybrominated diphenyl ethers (PBDEs). The measured concentrations varied with respect to the particular compound and landfill, but POPs were present at measurable levels in the leachates from all the examined landfills. The highest concentrations were found in the leachate from the landfill collecting waste from the capital of the province. In the leachates from younger landfills, the concentrations of lower halogenated compounds were higher than those of higher substituted congeners. Lower condensed PAHs showed higher concentrations in samples from all the examined sites.

A performance-based system for the long-term management of municipal waste landfills

Landfills have been the dominant alternative for disposal of solid waste and there are tens of thousands of closed landfills throughout the world that require a long-term management strategy. In contrast to approaches based on time or target values, this paper describes a performance-based methodology for evaluation of post-closure care (PCC). Using the methodology, critical components of PCC at a landfill, including leachate and gas management, groundwater monitoring and cover integrity, are considered to determine whether a landfill meets defined conditions for functional stability and can transition from regulated PCC to a post-regulatory custodial care program representing de minimus care activities only. The methodology is predicated on understanding the biological, chemical, and physical behavior of a landfill and the presence of sufficient data to verify expected trends in landfill behavior. If an evaluation suggests that a change can be made to PCC, the landfill owner must perform confirmation monitoring and then surveillance monitoring at a decreasing frequency to verify that the change is protective of human health and the environment. A hypothetical case study showed that using the methodology to evaluate site-specific PCC requirements could result in increased environmental protection at comparable cost by spending available funds where they are most needed.

Contribution of 3-D time-lapse ERT to the study of leachate recirculation in a landfill

Leachate recirculation is a key process in the operation of municipal waste landfills as bioreactors. It aims at increasing the moisture content to optimise the biodegradation. Because waste is a very heterogeneous and anisotropic porous media, the geometry of the leachate plume recirculation is difficult to delineate from the surface at the scale of the bioreactor site. In this study, 3-D time-lapse electrical resistivity tomography (ERT) was used to obtain useful information for understanding leachate recirculation hydrodynamics. The ERT inversion methodology and the electrode arrays were optimised using numerical modelling simulating a 3-D leachate injection scenario. Time-lapse ERT was subsequently applied at the field scale during an experimental injection. We compared ERT images with injected volumes to evaluate the sensitivity of time-lapse ERT to delineate the plume migration. The results show that time-lapse ERT can accomplish the following: (i) accurately locate the injection plume, delineating its depth and lateral extension; (ii) be used to estimate some hydraulic properties of waste.

Waste Generation and Landfill Diversion Dynamics: Decentralised Management and Spatial Effects

This paper provides analyses of municipal waste generation and landfill diversion dynamics based on an 8-year panel dataset for Italy covering 103 provinces. Although absolute declining for waste generation is a long way off, there are some first signals of increasing relative delinking and robust average landfill diversion. Spatial effects seem to be negligible, probably due to the strong decentralisation of waste management and policies: local, economic, policy and structural factors contribute to explaining the waste dynamics. Though North-South waste performances are showing some signals of convergence, greater efforts towards convergence of waste performances in a decentralised policy scenario are needed.

Batch and column tests of metal mobilization in soil impacted by landfill leachate

The percolation of landfill leachate, even in the absence of a high concentration of specific pollutant, may induce a strong modification of soil chemical and physical characteristics, due to the alteration of the natural equilibrium between the aqueous phase and the soil matrix. As a result, a huge amount of cations can be solubilized, thus inducing groundwater pollution. In this work batch and column experiments of metal mobilization from a soil sampled down gradient of a municipal waste landfill in Northern Italy are presented. The experiments were initially performed in batch scale on soil slurries at different pH and Eh. Distilled water was used first and then a groundwater sampled down-gradient in the same site. Subsequently, to better simulate the aquifer conditions, 50 d column tests were performed on 15 kg of saturated soil. The concentrations of Fe, Mn, and Ni were evaluated when these selected environmental parameters were altered. Results indicated a greater release when acidic conditions were achieved, a positive effect in this case of the addition of an oxidant and a great Mn mobilization when negative redox potentials were established.

Geophysical experiments for the pre-reclamation assessment of industrial and municipal waste landfills

Two examples of combined application of geophysical techniques for the pre-reclamation study of old waste landfills in Sardinia, Italy, are illustrated. The first one concerned a mine tailings basin and the second one a municipal solid waste landfill; both disposal sites date back to the 1970–80s. The gravity, shallow reflection, resistivity and induced polarization methods were employed in different combinations at the two sites, and in both cases useful information on the landfill's geometry has been obtained. The gravity method proved effective for locating the boundaries of the landfill and the shallow reflection seismic technique proved effective for the precise imaging of the landfill's bottom; conversely the electrical techniques, though widely employed for studying waste landfills, provided mainly qualitative and debatable results. The overall effectiveness of the surveys has been highly improved through the combined use of different techniques, whose individual responses, being strongly dependent on their specific basic physical characteristic and the complexity of the situation to be studied, did not show the same effectiveness at the two places.

Modelling waste stabilisation ponds with an extended version of ASM3

In this paper an extended version of IWA's Activated Sludge Model No 3 (ASM3) was developed to simulate processes in waste stabilisation ponds (WSP). The model modifications included the integration of algae biomass and gas transfer processes for oxygen, carbon dioxide and ammonia depending on wind velocity and a simple ionic equilibrium. The model was applied to a pilot-scale WSP system operated in the city of Florianópolis (Brazil). The system was used to treat leachate from a municipal waste landfill. Mean influent concentrations to the facultative pond of 1,456 g(COD)/m(3) and 505 g(NH4-N)/m(3) were measured. Experimental results indicated an ammonia nitrogen removal of 89.5% with negligible rates of nitrification but intensive ammonia stripping to the atmosphere. Measured data was used in the simulations to consider the impact of wind velocity on oxygen input of 11.1 to 14.4 g(O2)/(m(2) d) and sun radiation on photosynthesis. Good results for pH and ammonia removal were achieved with mean stripping rates of 18.2 and 4.5 g(N)/(m(2) d) for the facultative and maturation pond respectively. Based on measured chlorophyll a concentrations and depending on light intensity and TSS concentration it was possible to model algae concentrations.

Location analysis of the landfill of waste in Loznica

The subject of this paper regards the landfill of municipal and industrial waste in Loznica, actually its location and environmental hazards. The research was carried out in order to show the consequences of careless and incomplete evaluation of the conditions for a locating of a landfill in the example of Loznica. Besides the fact that it is located at the floodplain of the Drina River, the landfill is normally located to the direction of predominant wind, which has a significant influence on environmental dispersion processes. The landscape where the landfill is located has been impacted by flooded and groundwater and predominant wind, but on the other side, the environment has also been impacted by pollutants which come from the new system landscape-landfill. The results of the laboratory analysis help to target a gradual process of the soil contamination by heavy metals from the landfill, and to detect the general direction of contaminant migration, from southwest to northeast. Therefore, it is necessary to start working on recultivation and rehabilitation of the landfill and to begin with regional waste disposal. .

Environmental Health Insights into the 2010 Deepwater Horizon (BP) Oil Blowout

Environmental Health Insights into the 2010 Deepwater Horizon (BP) Oil Blowout

Improvement of electrical resistivity tomography for leachate injection monitoring

Leachate recirculation is a key process in the scope of operating municipal waste landfills as bioreactors, which aims to increase the moisture content to optimize the biodegradation in landfills. Given that liquid flows exhibit a complex behaviour in very heterogeneous porous media, in situ monitoring methods are required. Surface time-lapse electrical resistivity tomography (ERT) is usually proposed. Using numerical modelling with typical 2D and 3D injection plume patterns and 2D and 3D inversion codes, we show that wrong changes of resistivity can be calculated at depth if standard parameters are used for time-lapse ERT inversion. Major artefacts typically exhibit significant increases of resistivity (more than +30%) which can be misinterpreted as gas migration within the waste. In order to eliminate these artefacts, we tested an advanced time-lapse ERT procedure that includes (i) two advanced inversion tools and (ii) two alternative array geometries. The first advanced tool uses invariant regions in the model. The second advanced tool uses an inversion with a “minimum length” constraint. The alternative arrays focus on (i) a pole–dipole array (2D case), and (ii) a star array (3D case). The results show that these two advanced inversion tools and the two alternative arrays remove almost completely the artefacts within +/−5% both for 2D and 3D situations. As a field application, time-lapse ERT is applied using the star array during a 3D leachate injection in a non-hazardous municipal waste landfill. To evaluate the robustness of the two advanced tools, a synthetic model including both true decrease and increase of resistivity is built. The advanced time-lapse ERT procedure eliminates unwanted artefacts, while keeping a satisfactory image of true resistivity variations. This study demonstrates that significant and robust improvements can be obtained for time-lapse ERT monitoring of leachate recirculation in waste landfills.

The challenge of medical waste management: a case study in northwest Iran-Tabriz

This article presents the results of a descriptive cross-sectional study on medical waste management in Tabriz (Iran's fourth largest city). The study was conducted in 10 of 25 active hospitals of the city in the summer of 2007. The methodology of the present study was based on data collected from hospitals through a checklist, site visits (observation), and quantity analysis by weight. The results indicated that more than 13.59 tonnes day(-1) of total medical waste and 4.06 tonnes day(-1) of hazardous-infectious medical waste are generated by the active hospitals of the city. Currently, there are no practical instructions, or suitable supervision on different levels of waste management. The health authorities and hospital managers do not accept sufficient responsibility for the medical waste due to financial problems and the lack of awareness regarding the hazards of medical waste. Segregation and minimization of waste are not carried out correctly in any of the hospitals. The use of protective measures by staff and temporary storage areas was not in agreement with standards in 70 and 60% of the hospitals in the present study, respectively. About 50% of the hospitals had been equipped with an incinerator, but all but one (10%) of them had been phased out due to operation and maintenance problems, air pollution, etc. Almost all of the hospitals have a waste management officer, but there is not an effective training programme for the staff. Infectious-hazardous medical waste is mixed with general waste, and it is disposed of in a municipal waste landfill, which is an unsanitary dumpsite. Illegal segregation and recycling of medical waste is carried out at the final disposal site; therefore, there are concerns about environmental pollution and the transmission of infectious diseases. It is proposed that, through the allocation of increased budgets, implementation of integrated segregation, minimization of waste, and creation of a training programme in the hospitals, the quantity of medical waste would be decreased (by about 70.11%). Considering the previous unsuccessful experience of on-site incineration in Tabriz (and in Iran's other large cites), an amendment should be made to Iran's current hazardous waste regulations to have infectious-hazardous waste sent to a central off-site autoclave or incinerator for treatment. The off-site autoclave would have some advantages, such as decreased air pollution. Of course, some health officials oppose this plan. To test this plan and receive the official's approval, a central off-site autoclave can be put into practice as a pilot.

Benchmarking Method for Estimation of Biogas Upgrading Schemes

Benchmarking Method for Estimation of Biogas Upgrading SchemesThe paper describes a new benchmarking method proposed for estimation of different biogas upgrading schemes. The method has been developed to compare the indicators of alternative biogas purification and upgrading solutions and their threshold values. The chosen indicators cover both economic and ecologic aspects of these solutions, e.g. the prime cost of biogas purification and storage, and the cost efficiency of greenhouse gas emission reduction. The proposed benchmarking method has been tested at "Daibe" - a landfill for solid municipal waste.