Microbial community divergence and environmental responses across multi-phase landfill environments.

Municipal solid waste (MSW) landfills create the environmental pollutions due to problems related to toxins, leachate, and greenhouse gas, which are the growing environmental concerns, especially in developing countries. This paper presents a novel mathematical modelling for simulating the spread of heavy metals in soil layers in the MSW landfills. A new mathematical modelling procedure is studied for deriving the governing equation which describes the time varying concentration of pollutants in the leachate in a 3-dimensional (3D) space of soil layers. A Finite Element Method (FEM) based algorithm is then constructed to solve numerically the governing equation over time in 3D space for effectively analyzing the variation of pollutants concentrations. Finally, the applicability and advantages of the proposed novel method are demonstrated through the case study with soil samples collected from the actual MSW landfill. The successfully developed algorithm can be applied to model and predict the spread of different heavy metals in the MSW landfill sites; and to develop effective solutions and policies for solid waste classification and management, in order to minimise the negative impacts from the potential risk of the toxic heavy metal pollutions, soil contaminations and groundwater pollutions in the areas nearby the MSW landfill.

The relevance of the article is conditioned by the fragmentation of not only official, but also scientific ideas about the contribution of municipal solid waste (MSW) landfills to environmental pollution, the fragmentation of hydrobiological research as such, and the need for reliable data on the structure and mechanisms of formation of aquatic ecosystems. The aim of the work is to discover the unity and differences in the state of aquatic ecosystems formed in the zone of influence of MSW landfills similar in life cycle stage (already closed and reconstructed). The objectives of the work were to select four representative closed MSW landfills, to collect official data on their technical condition, to conduct a comprehensive environmental survey with obligatory sampling and hydrobiological and hydrochemical analyses, to analyze the results in terms of assessing compliance with standards, to search for the dependence of pollution on the life cycle stage of the MSW landfill and to formulate assumptions about the conditions of ecosystem formation under the effect of a complex of anthropogenic impacts (including those not related to the MSW landfills). The article presents the results of an environmental study of the tributaries of the Likhoborka river (near the Dolgoprudnensky MSW landfill), a tributary of the Radomlya river (in the village Radumlya near the former illegal MSW landfill), the Nara River (near the Sliznevo MSW landfill), and the Chernichka River (near the Tsarevo MSW landfill). Descriptions of other economic objects in their catchment areas and assumptions about the possible contribution of these additional sources to the pollution of aquatic ecosystems are given. The methodology of investigation, sampling for hydrochemical and hydrobiological analyses and their results are presented. Moderate pollution both before and after the MSW landfills was determined by calculating the Pantle-Buck index. Changes in species composition and abundance at the second site relative to the first site were monitored. The WPI calculation revealed generally moderate background pollution (higher in the Dolgoprudny area due to at least four concentrated discharges not associated with the MSW landfill, and lower in the ecologically safe area due to proximity to the source and the unloaded background of Tsarevo). Characteristic increases in pollutant concentrations (mainly ammonium, which is problematic for all areas) were observed. The conclusion about the relatively small contribution of the closed MSW landfills to river pollution was formulated.

Evaluation of methane emission from MSW landfills in China, India, and the U.S. from space using a two-tier approach.

This document provides guidance for meeting: (1) Guidelines for the Land Disposal of Solid Waste (40 CFR 241); (2) Criteria for Classification of Solid Waste Disposal Facilities and Practices (40 CFR 257); and (3) Criteria for Municipal Solid Waste Landfills (MSWLFs) (40 CFR Part 258). Revisions to 40 CFR 257 and a new Part 258 were published in the Federal Register (56 FR 50978, 10/9/91). The Guidelines for the Land Disposal of Solid Waste set requirements and recommended procedures to ensure that the design, construction, and operation of land disposal sites is done in a manner that will protect human health and the environment. These regulations are applicable to MSWLFs and non-MSWLFs (e.g., landfills used only for the disposal of demolition debris, commercial waste, and/or industrial waste). These guidelines are not applicable to the, land disposal of hazardous, agricultural, and/or mining wastes. These criteria are to be used under the Resource Conservation and Recovery Act (RCRA) in determining which solid waste disposal facilities pose a reasonable possibility of adversely affecting human health or the environment. Facilities failing to satisfy these criteria will be considered to be open dumps which are prohibited under Section 4005 of RCRA. The Criteria for MSWLFs are applicable only to MSWLFs, including those MSWLFs in which sewage sludge is co-disposed with household waste. Based on specific criteria, certain MSWLFs are exempt from some, or all, of the regulations of 40 CFR 258. MSWLFs that fail to satisfy the criteria specified in 40 CFR 258 are also considered open dumps for the purposes of Section 4005 of RCRA. Through the use of a series of interrelated flow diagrams, this guidance document directs the reader to each design, operation, maintenance, and closure activity that must be performed for MSWLFs and non-MSWLFs.

Estimation of settlement is a matter of prime importance for the maintenance of municipal solid waste (MSW) landfills. Settlement of MSW landfill used to take place for a long duration, and the total displacement can approach up to 30% of original landfill height. The main phases of settlement in MSW landfills are initial compression, primary compression, and long-term secondary compression. The mechanisms involved in the waste settlement are densification, placement of finer particles in the voids of larger size particles, physical–chemical change, and bio-chemical decomposition. The factors which affect the settlement values are initial density or void ratio of the solid waste, placement sequence, decomposable materials, leachate levels, and landfill operation methods. A large value of settlement after non-functioning of the landfill is undesirable from management angle as it can cause surface ponding, development of cracks in clay liners (such as compacted clay liners), and tear in the geomembrane layer. Therefore, understanding of total landfill settlement is necessary for landfill design and the future construction over it. Different prediction models are used to determine the displacement of a typical MSW landfill. These models are based on soil mechanics-based model, rheological model, empirical model, and biodegradation-induced settlement model. The model parameters are taken from data available in the published literature. Measured settlement data from each model is displayed as settlement-versus-time graph. In the study, it can be seen that the predicted settlement magnitude differs notably depending on the prediction model used and the selection of parametric values. Marques (2001) model was found out to predict the settlement more closely as it considers all the mechanisms involved in the settlement in good proportion.KeywordsLandfillsMunicipal solid wastesSettlementModelsPredictions

Purpose. Physical-chemical processes occurring during fires within municipal solid waste (MSW) landfills have been studied quite thoroughly by now. Previous studies have established that water streams in metastable phase state are the most effective means for extinguishing these fires. However, droplets diameter of aqueous medium in metastable phase state at which the extinguishing time of these fires will be minimal, has not been defined theoretically or experimentally. The aim of the work is to establish the dependence of MSW landfills extinguishing time on droplets diameter of aqueous medium in metastable phase state (AMMPhS). The authors' objectives have been the existing models analysis, developing a model for extinguishing MSW landfills with aqueous medium in metastable phase state in the PyroSim hardware and software system, and mathematical modeling of MSW landfills flooding process with aqueous medium in metastable phase state. Methods. Analysis and synthesis methods have been used to assess the available data. The theory of branched-chain combustion processes has been used to study flooding processes. Findings. The study has allowed creating a model for extinguishing MSW landfills with aqueous medium in metastable phase state. The dependences of extinguishing time, humidity in local extinguishing volume on AMMPhS droplets diameter have been established. Research application field. The obtained models can be used to improve fire extinguishing efficiency at MSW landfills. The results of the study will also allow forming theoretical basis for describing the dependence of the extinguishing time of fires at MSW landfills on AMMPhS droplets diameter. Conclusions. Based on the results of the conducted modeling of municipal solid waste landfill fire extinguishing via water systems with different droplet distributions in the extinguishing medium volume, it has been found that decrease in the municipal solid waste landfill extinguishing time is observed with increase in the droplet diameter from 10 to 50 μm. For effective suppression of municipal solid waste combustion at landfills using AMMPhS it is advisable to use a barrel with a nozzle in the form of a washer with a sharp edge, which allows for the production of droplets with a diameter of 50 μm.

Recent studies have indicated that Eastern China might be a potential source region of increased atmospheric chlorofluorocarbons (CFCs). To investigate this possibility, a field measurement was carried out from October to December 2017 for identifying the ambient concentration levels of representative trichlorofluoromethane (CFC-11), dichlorodifluoromethane (CFC-12), trifluorotrichloroethane (CFC-113), and tetrafluorodichloroethane (CFC-114) at the residential and municipal solid waste (MSW) landfills and industrial sites in Eastern China. The ambient mixing ratios of CFCs at residential sites were almost within 20% enhancements of the global background sites. The highest levels of CFCs were observed at the MSW landfill sites. Moreover, CFC-11 and CFC-113 concentrations at MSW landfill, which was in service, were two times higher than that at completed MSW landfill. Mean concentrations of 322 pptv for CFC-11, 791 pptv for CFC-12, 91 pptv for CFC-113, and 16 pptv for CFC-114 at various industrial sites were higher than those at residential sites, but they were obviously lower than that at MSW landfill in use. A poor intercorrelation between the CFCs indicated that they did not come from the same source. Higher concentrations measured in this study compared with background sites indicates that MSW landfills could be an unintentional emission source and there are still substantial amounts of CFCs being stored in banks that may discharge CFCs into the atmosphere in Eastern China.

Characterization of per- and polyfluoroalkyl substances (PFAS) and other constituents in MSW landfill leachate from Puerto Rico

Metal loss from treated wood products in contact with municipal solid waste landfill leachate

The objective of this research is to investigate the intrinsic biodegradation potential of the municipal solid waste (MSW) landfill ecosystem for chlorinated aliphatic hydrocarbons (CAHs). The research was conducted in two complementary systems: simulated landfill bioreactors and batch degradation experiment in serum bottles. Refuse samples excavated from a MSW landfill were tested in laboratory bioreactors operated with leachate recirculation and gas collection. Tetrachloroethene (PCE) and trichloroethene (TCE) were added to reactors and maintained at 20 μM each in leachate to simulate the long-term exposure of refuse microorganisms to CAHs in landfills. Anaerobic microbial cultures were derived from reactors at two different stages of refuse decomposition: active refuse decomposition stage representing young landfills and maturation phase representing aged landfills. These cultures were tested in serum bottles for their abilities to biodegrade target CAHs. Results of this study show that MSW landfills have an intrinsic reductive dechlorination capacity for PCE and TCE. The decomposition of refuse also enhanced reductive dechlorination in this study. This research suggests the potential to develop engineering strategies to promote chlorinated solvent degradation concurrently with refuse decomposition in MSW landfills.

Clay-solidified grouting curtains are commonly used for remediation by containment or pollution prevention, in addition to their use as a barrier to water flow in municipal solid waste(MSW) landfills. A hydrological model of water flow and a hydrodynamic model of contaminant are presented to simulate the migration of leachate through clay-solidified grouting curtain in MSW landfills, with particular attention paid to the role of diffusive and adsorptive fluxes in contaminant transport. The models were applied to simulate the sensitivity of the curtain’s behavior to changes in parameters, such as thickness, depth, permeability coefficient, diffusion coefficient, resistance coefficient and concentration, and also to demonstrate the contaminant distribution on the evolution of travel time and offset distance of clay-solidified grouting curtain in landfills. It is found that a part of leachate components stays or is retarded in clay-solidified grouting curtain by precipitate or exchange, the retention rate is closely related to composition of clay-solidified grouting curtain, more than 80%, and the maximum occurs at the cementclay ratio of 2 : 4 under experimental conditions. Contamination distribution is variable on travel time and offset distance, the highest concentration takes place where the contamination intensity is nearest to the pollution resource or takes place at early middle period of transport, and the pollutant attenuates gradually. The results indicate that claysolidified grouting curtain with a proper thickness, a low permeability coefficient and a high resistance coefficient might serve as a sufficiently effective vertical barrier against leachate seepage and contamination migration in MSW landfills.

Prediction of long‐term settlement and control of gas pollution to the environment are two principle concerns during the management of municipal solid waste (MSW) landfills. The behavior of settlement and gas flow in MSW landfills is complicated due to the combined effect of mechanical deformation of the solid skeleton and continuous biodegradation of the waste. A one‐dimensional settlement and gas flow model is presented in this paper, which is capable of predicting time evolution of settlement as well as temporal and spatial distribution of gas pressure within multi‐layered landfills under a variety of operating scenarios. The analytical solution to the novel model is evaluated with numerical simulation and field measurements. The resulting efficiency and accuracy highlight the capability of the proposed model to reproduce the settlement behavior and gas flow in MSW landfills. The influences of operating conditions and waste properties on settlement and gas pressure are examined for typical MSW landfills. Copyright © 2009 John Wiley & Sons, Ltd.

Quantification of methane emissions from municipal solid waste landfills in China during the past decade

As a result of extensive use of engineered nanomaterials (ENMs) in consumer products, significant amounts of ENMs are eventually released to the environment and find their way to wastewater treatment plants, incineration plants and landfills. Recent concerns about the potential impacts of these materials on the environment and human health, have diverted researchers’ interest to investigate the behaviour of inorganic, metallic/metal oxide ENMs in conventional activated sludge wastewater treatment and anaerobic sewage sludge digestion systems. However, related information about the presence and fate of such ENMs during waste stabilization in municipal solid waste (MSW) landfills which remains a widely used method of solid waste management, is scarce in literature. Therefore, in this paper, recent information about the detection methods and fate of the most commonly used metal oxide ENMs such as TiO2, ZnO, Ag and SiO2 in MSW landfills was revealed. The complexity of the factors influencing ENMs retention and transport mechanisms was discussed. Future research needs relating to the fate of ENMs in MSW were also identified.

Treatment of leachate from municipal solid waste landfill