Landfill Samples Research Articles

Characterization of methanogens from landfill samples: implications for sustainable biogas production

This case study aimed to isolate and identify methanogenic bacteria from landfill soil, mud, and leachate samples to assess their role in anaerobic digestion and biogas production. Anaerobic digestion involves the breakdown of organic matter by a diverse group of bacteria under oxygen-free conditions, resulting in the production of methane and carbon dioxide. The collected samples from the landfill were cultured in a modified mineral salt medium (MSM). Microscopic observations revealed distinct coccus and bacillus morphologies of the isolated methanogenic bacteria. Gas production experiments and substrate utilization studies identified two types of methanogens. Methanosarcina sp., which utilized acetate and methanol for methane production, and Methanobacterium sp., utilizing hydrogen and carbon dioxide, as well as acetate. Scanning electron microscope (SEM) analysis confirmed the different morphotypes of the isolated methanogens. The study findings demonstrated the presence of diverse methanogens in the landfill environment, contributing to anaerobic digestion and biogas production.

Comparison of the PFAS and physical-chemical parameter fluctuations between an ash landfill and a MSW landfill

Studies of per- and polyfluoroalkyl substances (PFAS) fluctuations at landfills have focused on municipal solid waste (MSW) leachate. Few studies exist that evaluate fluctuations (defined by the coefficient of variation, CV) in MSW incinerator ash (MSWA) landfill leachate and that evaluate PFAS fluctuations in stormwater, groundwater, and treated liquids on-site. In this study, aqueous landfill samples (leachate, treated leachate, stormwater, gas condensate, ambient groundwater, and effluent from a groundwater remediation system) were collected from a MSW and an MSWA landfill geographically located within close proximity (less than 40 km). The objective of this study was to compare the leachate compositions between these two landfill types and to evaluate temporal variations. Results indicated that the CV of total detected PFAS concentrations in leachate was higher for the MSW landfill (CV = 43 %) compared to the MSWA landfill (CV = 16 %). The total detected PFAS concentration in MSW leachate samples (mean: 9641 ng/L) was higher than in MSWA leachate samples (mean: 2621 ng/L) (p < 0.05). Within a landfill, PFAS concentrations were correlated (rs > 0.6, p < 0.05) with alkalinity, total organic carbon (TOC), and ammonia. Results from the on-site leachate treatment system at the MSW landfill indicated reductions in COD, TOC, and ammonia; however, the ∑26PFAS concentration increased 3 % after the treatment. Overall, results demonstrated that differences between landfill types and fluctuations in PFAS within landfills should be considered when designing landfill leachate collection and treatment systems to remove PFAS. The comparative analysis in this study can provide insights into optimizing leachate management for MSW and MSWA landfills.

Quantification and molecular characterization of intact rotavirus species A (RVA) in municipal solid waste leachate.

Leachate comprises a solid waste decomposition product found fresh in collection trucks or as an effluent in landfills. This study aimed to assess the occurrence, concentrations, and genetic diversity of intact rotavirus species A (RVA) in solid waste leachate. Leachate samples were concentrated by ultracentrifugation, treated with propidium monoazide (PMA), and exposed to LED photolysis. Treated and untread samples were extracted using the QIAamp Fast DNA Stool mini kit, and nucleic acids were screened for RVA employing a Taqman® Real-time PCR. The PMA RT-qPCR method detected RVA in eight out of nine truck samples and in 15.40% (2/13) of the landfill leachate samples. The RVA concentrations in the PMA-treated samples ranged from 4.57×103 to 2.15×107 genomic copies (GC) 100 mL-1 in truck leachate and from 7.83×103 to 1.42×104 GC 100 mL-1 in landfill samples. Six truck leachate samples were characterized as RVA VP6 genogroup I2 by partial nucleotide sequencing. The high intact RVA detection rates and concentrations in truck leachate samples indicate potential infectivity and comprise a warning for solid waste collectors concerning hand-to-mouth contact and the splash route.

Relationships between per- and polyfluoroalkyl substances (PFAS) and physical-chemical parameters in aqueous landfill samples

Variable chemistries of liquids from landfills can potentially impact levels of per- and polyfluoroalkyl substances (PFAS). The objective of the current study was to evaluate relationships between physical-chemical properties (bulk measurements, oxygen demand components, and metals) and PFAS concentrations in different types of aqueous landfill samples. Aqueous landfill samples were collected from 39 landfill facilities in Florida, United States. These samples included leachates from landfills that receive different waste types, such as municipal solid waste incineration ash (MSWA), construction and demolition debris (C&D), and municipal solid waste (MSW). Additional aqueous landfill samples were sourced from treated landfill leachate, gas condensate, stormwater, and groundwater from within and near the landfill boundaries. Results showed significant correlations (p < 0.05) between ∑26PFAS and alkalinity (rs = 0.83), total organic carbon (TOC) (rs = 0.84), and ammonia (rs = 0.79) for all leachate types. Other physical-chemical parameters that were significantly correlated (rs > 0.60, p < 0.05) with PFAS included specific conductivity, chemical oxygen demand (COD), and to a lesser extent, total dissolved solids (TDS) and total solids (TS). For gas condensates, PFAS was significantly correlated with TOC. Stormwater and groundwater, within and near the landfill boundaries, had considerably lower levels of PFAS and had a minimal correlation between PFAS and physical-chemical parameters. Although PFAS concentrations and physical-chemical parameters and their correlations varied between different types of aqueous landfill samples, results suggest that physical-chemical properties can be useful indicators of relative PFAS concentrations within a leachate type. More research is needed to validate the mechanisms that relate physical-chemical parameters to PFAS concentrations in landfill leachates.

Cloacimonadota metabolisms include adaptations in engineered environments that are reflected in the evolutionary history of the phylum.

Phylum Cloacimonadota (previously Cloacimonetes, WWE1) is an understudied bacterial lineage frequently associated with engineered and wastewater systems. Cloacimonadota members were abundant and diverse in metagenomic datasets from a municipal landfill, prompting an examination of phylogenetic relationships, metabolic diversity, and pangenomic dynamics across the phylum, based on the 30 publicly available genomes and 24 new metagenome-assembled genomes (MAGs) from landfill samples. We found that Cloacimonadota have distinct evolutionary histories associated with engineered versus natural environments and identified genomic features and metabolic strategies that correlate to habitat of origin. Metabolic reconstructions for MAGs predict an anaerobic, acetogenic, and mixed fermentative and flavin-bifurcation-based anaerobic respiratory lifestyle for the majority of Cloacimonadota surveyed. Genomes from engineered ecosystems encode a suite of genes not typically found in genomes from natural environments including acetate kinase, genes for cysteine degradation to pyruvate, increased diversity of carbon utilization enzymes, and different mechanisms for generating membrane potential and ATP synthesis. This phylum-level examination also clarifies the distribution of functions previously observed for members of the phylum, where propionate oxidation and reverse TCA cycles are not common components of Cloacimonadota metabolism.

Mobility of metals and metalloids from SHOS coal ash and slag deposit: mineralogical and geochemical constraints.

Deposits remained after coal combustion are a well-known occurrence in the world; unfortunately, only a small percentage of such deposits are adequately regulated and, consequently, pose a serious threat to the local environment. Attenuation of negative consequences presupposes knowledge of a number of features, both of the deposit and the local environment as well the interaction with local biota. In this study, unregulated waste generated from decades of coal mining and combustion of superhigh-organic-sulfur Raša coal, enriched in Se-U-Mo-V and located in a vulnerable karst region, was investigated. To assess the impact of landfill on the environment, in addition to its general geochemical and mineralogical features, the human health risk was assessed and the leaching of elements from the landfill, local soil, and the coal itself was investigated. For the latter, three extraction procedures, ASTM, EP, and TCLP (pH 4.93 and 2.9), were employed, mimicking different environmental conditions, including the sporadic occurrence of acid rains in the region. The soil around the landfill displayed enrichment in the majority of elements compared to expected values, with exception of Se, Mo, U, V, Sr, and Cu found at the highest levels in landfill samples. Mobility of elements was found to be controlled by both pH and mineralogy (carbonates and sulfates), whereby the overall highest relative mobility was observed in landfill samples for elements prevalently bound to sulfate phases. Calculated Hazard Quotient describes this landfill as a risk to the environment and human health through different pathways.

Leaching and Geochemical Modelling of an Electric Arc Furnace (EAF) and Ladle Slag Heap

Old metallurgical dumps across Europe represent a loss of valuable land and a potential threat to the environment, especially to groundwater (GW). The Javornik electric arc furnace (EAF) and ladle slag heap, situated in Slovenia, was investigated in this study. The environmental impact of the slag heap was evaluated by combining leaching characterization tests of landfill samples and geochemical modelling. It was shown that throughout the landfill the same minerals and sorptive phases control the leaching of elements of potential concern, despite variations in chemical composition. Although carbonation of the disposed steel slags occurred (molar ratio CO3/(Ca+Mg) = 0.53) relative to fresh slag, it had a limited effect on the leaching behaviour of elements of potential concern. The leaching from the slag heaps had also a limited effect on the quality of the GW. A site-specific case, however, was that leachates from the slag heap were strongly diluted, since a rapid flow of GW fed from the nearby Sava River was observed in the landfill area. The sampling and testing approach applied provides a basis for assessing the long-term impact of release and is a good starting point for evaluating future management options, including beneficial uses for this type of slag.

Evaluation of Occupational Exposure Risk for Employees Working in Dynamic Olfactometry: Focus On Non-Carcinogenic Effects Correlated with Exposure to Landfill Emissions

This work aims to evaluate the non-carcinogenic health effects related to landfill odor emissions, therefore focusing on workers involved in dynamic olfactometry. Currently, the most common technique to quantify odor emissions is dynamic olfactometry, a sensorial analysis involving human assessors. During the analysis, assessors are directly exposed, at increasing concentrations, to odor samples, and thus to the hazardous pollutants contained therein. This entails the need to estimate the associated exposure risk to guarantee examiners’ safety. Therefore, this paper evaluates the exposure risk for olfactometric examiners to establish the minimum dilution level to be adopted during the analysis of landfills’ odorous samples to guarantee panelists’ safety. For this purpose, an extensive literature review regarding the pollutants emitted by landfill odor sources was conducted, comparing compounds’ chemical concentrations and threshold limit values (TLVs) to calculate the Hazard Index (HI) and thus establish a minimum dilution value. The data collected indicate that a non-negligible non-carcinogenic risk exists for all landfill emissions considered. However, from the data considered, the minimum dilution factor to be adopted is lower than the typical odor concentration observed for these sources. Therefore, the olfactometric analysis of landfill samples can be generally conducted in safe conditions.

Evidence of thermophilic waste decomposition at a landfill exhibiting elevated temperature regions

There have been several reports of landfills exhibiting temperatures as high as 80 to 100 °C. This observation has motivated researchers to understand the causes of the elevated temperatures and to develop predictive models of landfill temperature. The objective of this research was to characterize the methanogenic activity of microbial communities that were derived from landfill samples excavated from a section of a landfill exhibiting gas well temperatures above 55 °C. Specific objectives were to: (1) determine the upper temperature limit for methane production; (2) evaluate the kinetics of methane generation when landfill-derived microcosms are incubated above and below their excavation temperature and derive a temperature inhibition function; and (3) evaluate microbial community shifts in response to temperature perturbations. Landfill microcosms were derived from 57 excavated landfill samples and incubated within ±2.5 °C of their excavation temperature between 42.5 °C and 87.5 °C. Results showed an optimum temperature for methane generation of ~57 °C and a 95% reduction in methane yield at ~72 °C. When select cultures were perturbed between 5 °C below and 15 °C above their in-situ temperature, both the rate and maximum methane production decreased as incubation temperature increased. Microbial community characterization using 16S rRNA amplicon sequencing suggests that thermophilic methanogenic activity can be attributed to methanogens of the genus Methanothermobacter. This study demonstrated that from a microbiological standpoint, landfills may maintain active methanogenic processes while experiencing temperatures in the thermophilic regime (<72 °C).

ISOLASI BAKTERI DARI TANAH TEMPAT PEMBANGAN AKHIR (TPA) AIR SEBAKUL SEBAGAI AGEN BIODEGRADASI LIMBAH PLASTIK POLYETHYLENE

This study aims to obtain the bacteria of Pseudomonas from the land of TPA Air Sebakul Bengkulu City as a plastic degrading agent and measure the ability of bacteria to degrade Low Density Polyethylene (LDPE) and Oxium plastic. The research was conducted from February to August 2019, at the Laboratory of Biology and Chemistry Learning, Faculty of Teacher Training and Education, University of Bengkulu. Air Sebakul landfill samples were taken at the coordinate point 3o49 '27.8 "S 102o20 '48.4" E. Isolation of plastic degrading bacteria using selective media King's B Agar added with 2% Polyethylen Glycol (PEG) to test the ability to develop bacterial isolates in plastic-based media. The steps of this research are bacterial isolation, bacterial purification and bacterial selection, macroscopic and microscopic identification of bacteria (Gram staining) and plastic biodegradation test with Mineral Salt Agar (MSM) media. Determination of the% weight loss of LDPE and oxium plastics in the biodegradation process was carried out for 30 days with time variations of 10, 20 and 30 days. The results of bacterial isolation based on morphological characteristics and gram staining test of P-1 bacterial isolate have similarities with Pseudomonas aeruginosa. So that the P-1 bacterial isolate is thought to be a Pseudomonas aeruginosa bacterium. The bidoegradation of LDPE and oxium plastics with isolates of P-1 bacteria for 10, 20 and 30 days respectively was able to degrade oxium plastics by 2.43, 5.17 and 9.86% while LDPE plastics by 1.13, 2 and 1 , 17%.

The Correlation between Bacteria and Parasite Patterns on Flies with Prevalence of Fly Vector-Borne Disease at the Market and the Landfill in Jember District, Indonesia

Fly vector-borne diseases are the potential disease that can trigger an outbreak. The fly lives in a dirty placewith poor sanitation, such as the market and the landfill. Some pathogens that can be transmitted by fliesmechanically were bacteria such as Escherichia coli, Shigella, Salmonella, Vibrio cholera and parasites suchas Balantidium coli, Entamoeba histolytica and Giardia lamblia. This study aimed to analyze the correlationbetween bacteria and parasite patterns on flies and the prevalence of fly vector-borne diseases. This researchwas conducted from May 2019 to March 2020. The flies samples were collected randomly at each researchlocation, i.e., Tanjung Market and the Pakusari landfill. The bacteria and parasites identifications werecarried out at the Microbiology and Parasitology Laboratory, Faculty of Medicine, University of Jember.The data of disease prevalence was collected in a cohort from the health centers around research locations.This study found three bacteria in market samples, 18 cases of fly vector-borne diseases and four bacteriain the landfill samples and 10 cases of fly vector-borne disease. The study indicated a significant correlationbetween bacteria and parasite patterns on flies with the prevalence of fly vector-borne diseases in the market,but no correlation in the landfill.

Screening and Isolation of Polyhydroxyalkanoates (PHA)-Producing Bacteria from Landfill by using Cocoa Pod Husks as Carbon Source

Polyhydroxyalkanoates (PHA) are bioplastics, produced by various bacteria as food and energy reservoir. PHA is an alternative for synthetic plastic because they are environmentally friendly and can be degraded naturally by microorganisms. One of the important factors for the growth of PHA producing bacteria is an excess of carbon supply. In order to reduce the overall cost of PHA production, a low cost pure substrate, which is cocoa pod husks (CPH) was used as a carbon source. The objectives of this study were to isolate and screen PHA producing bacteria from landfill samples which are leachate and soil, to identify the PHA producing bacteria by using morphological characterization and 16s rDNA gene sequencing and to determine the best percentage of CPH that can be used as a carbon source for PHA producing bacteria. PHA producing bacteria from leachate and soil from landfill in Jeram, Selangor were screened by using Nile Blue A staining method. Two potential PHA producers with the brightest fluorescence under UV light from each samples were isolated and characterized by using morphological and molecular identification. Results of morphological identification shows all bacterial isolates have a rod shape and have a capsule, three bacterial isolates (L4, S3, S5) have an endospore while the remaining does not have endospore (L1). Three out of four were Gram positive bacteria (L4, S3, S5) and the remaining was Gram negative bacteria (L1). These isolates were confirmed of their identity as K. pneumoniae (L1), B. cereus (L4 &amp; S3) and B. toyonensis (S5) using 16s rDNA gene sequencing. Different concentration of CPH, which are 2% (w/v), 5% (w/v), 7% (w/v) and 10% (w/v) were used to study the best percentage of CPH that can be used as carbon source. PHA accumulation was the highest at 7% (w/v) for all bacterial species tested and lowest at 10% (w/v) CPH except for B. toyonensis. Therefore, K. pneumoniae, B. cereus and B. toyonensis which isolated from landfill show the ability to produce PHA and the used of 7% (w/v) cocoa pod husks as carbon source give the highest PHA accumulation.

Landfill leachate treatment by sorption in magnetic particles: preliminary study

Leachates are still an open issue in environmental protection. Many of the applied methods for their treatment present low efficiency and thus need to be used collectively. In practice reverse osmosis is mostly used, as it is the most effective option, regardless of its cost. Magnetic methods to treat effluents have been used for water and wastewater treatment by the use of magnetic particles together with magnetic separation for the removal of contaminants. However, large-scale applications are few or even non-existent when we deal with complex contaminated media such as landfill leachates, for which not even research studies at laboratorial scale with real samples have been done yet. In this work, we apply for the first time magnetic sorption for the treatment of leachates, and close the full cycle by studying the regeneration and re-use of the magnetic particles; we also study the influence of the concentration of magnetic particles, the use of several pre-treatment methodologies and the type of particle used in the process, in real landfill samples from the waste treatment plant of Salamanca (Spain), for the removal of COD, NO3−, NO2−, NH4+, Total-N, PO43−, SO42− and Cl−. Regeneration of the magnetic particles after being used in the sorption stage is also studied, as well as their efficiency regarding their re-use. It is also determined the optimum number of batches for complete desorption and for regeneration of the particles, the effect of successive regeneration and re-use cycles, the use of two different regeneration methods, the efficiency of the desorption, the effect of the quantity of solvent and the influence of the time of sorption. Due to its innovative character and the complexity of the media, this work represents a first preliminary approach and, although some promising results have been obtained, further studies are required to completely understand and evaluate the proposed treatment process.

Presence of β-Lactamases Encoding Genes in Soil Samples from Different Origins

The functional classification of β-lactamases is done through assessing their ability to hydrolyze specific β-lactams and its inactivation by inhibitors. This study investigated the β-lactamases encoding genes present in soil samples from different origins (landfill, preservation area, and soil from a farm). Genes codifying for ESBL enzymes bla SHV, bla TEM-116 and bla OXA-1 were found in all analyzed samples. Gene for ESBL bla CTX-M-14 was detected in the landfill and farm soil samples, but they were not found in the preservation area, while bla OXA-48-like was present just in the soil from the landfill. The gene for the MBL bla VIM was found in the soil sample from a farm. The results indicate that bla SHV, bla TEM-116, and bla OXA-1 genes are scattered in soils with and without potential contaminants; however, genes bla CTX-M-14, bla OXA-48, and bla VIM were detected just in polluted areas.

Mass spectrometric fragmentation and photocatalytic transformation of nicotine and cotinine.

Nicotine and cotinine are, respectively, alkaloids produced mainly by the Solanaceae plant family, especially tobacco, and its most important human metabolite. These compounds are frequently found as contaminants in wastewater or landfill samples and they could be used to evaluate pollution by tobacco use. The aim of this study is to improve the knowledge about possible transformation pathways of nicotine and cotinine. This would help the identification of degradants by using HPLC coupled with a high resolving power mass analyzer (LTQ-Orbitrap). In addition, we evaluated toxicity on bioluminescent photobacteria to indicate possible relationships between the formation of transformation products and their toxic effects. The transformation of nicotine and cotinine and the formation of intermediate products were evaluated adopting titanium dioxide as photocatalyst. The structural identification of photocatalytic transformation products of these two alkaloids was based on LC/multistage MS experiments. High-resolution MS allowed the elemental composition of these products to be hypothesized. The evolution of toxicity as a function of the irradiation time was also studied using a bioluminescent photobacterium (Vibrio fischeri) test. Several products were formed and characterized using HPLC/HRMSn . The main photocatalytic pathways involving nicotine and cotinine appear to be hydroxylation, demethylation and oxidation. Nine degradants were formed from nicotine, including cotinine. Seven degradants were generated from cotinine. There is no transformation product in common between the two studied molecules. The study of photocatalytic degradation allowed us to partially simulate human metabolism and the environmental transformation of the bioactive alkaloid nicotine. We searched for some of the identified transformation products in river water and landfill percolate by solid-phase extraction and HPLC/HRMS and eventually their presence was confirmed. These new findings could be of interest in further metabolism and environmental pollution studies. Copyright © 2016 John Wiley & Sons, Ltd.

BMP estimation of landfilled municipal solid waste by multivariate statistical methods using specific waste parameters: case study of a sanitary landfill in Turkey

The main objective of this study was to determine whether methane potential of waste could be estimated more easily by a limited number of waste characterization variables. 36 samples were collected from 12 locations and 3 waste depths in order to represent almost all waste ages at the landfill. Actual remaining methane potential of all samples was determined by the biochemical methane potential (BMP) tests. The cumulative methane production of closed landfill (cLF) samples reached 75–125 mL at the end of experiment duration, while the samples from active landfill (aLF) produced in average 216–266 mL methane. The average experimental k and L 0 values of cLF and aLF were determined by non-linear regression using BMP data with first-order kinetic equation as 0.0269 day−1–30.38 mL/g dry MSW and 0.0125 day−1–102.1 mL/g dry MSW, respectively. The principal component analysis (PCA) was applied to analyze the results for cLF and aLF along with BMP results. Three PCs for the data set were extracted explaining 72.34 % variability. The best MLR model for BMP prediction was determined for seven variables (pH–Cl–TKN–NH4–TOC–LOI–Ca). R 2 and Adj. R 2 values of this best model were determined as 80.4 and 75.3 %, respectively.

Comparative Characterisation of Closed and Active Landfill Composites Using EDX, FTIR and Proximate Techniques

The elemental and chemical constituents of an active and a closed landfill were compared using Fourier transform-infrared (FTIR) spectroscopy, scanning electron microscope/energy-dispersive X-ray spectroscopy, and proximate analysis. The two landfills had similar major elemental constituents representing 96.5 and 98.4 % of elemental composition for the closed (O > C > Si > Fe > Ca > Al) and active (C > O > Si > Al > Ca > Fe) landfill samples respectively. The average concentration of Al was significantly higher (p = 0.024) in the active landfill, while Ca was significantly higher (p = 0.023) in the closed landfill. Cluster analysis revealed that similarities were more influenced by the level of composite degradation (more degraded/less degraded) than by depth or seasonal variations. Samples from both landfills showed FTIR absorption peaks that indicated mineralisation and stability of waste constituent. Active landfill samples showed distinguishing peaks at 3690 and 3619 cm−1 attributed to O–H vibration of clayey mineral (kaolin), while closed landfill samples were characterised by a carbonates peak at 873 cm−1. For both landfills, the average ash content (>51 %) of the waste was above the level considered suitable for energy recovery from waste. These findings inform strategic decisions in management of the landfills and in the determination of possible alternative uses for landfill waste.

Compositional analysis of excavated landfill samples and the determination of residual biogas potential of the organic fraction

The objectives of this study were to assess the biogas potential of landfilled materials and to further validate the suitability of the enzymatic hydrolysis test EHT as a valuable alternative to substitute the standardised test currently in use (BMP). Both tests were applied to a range of landfill waste samples. The waste composition and volatile solids content (VS) profile together with the BMP test results showed that the biogas potential of the waste samples was directly related to their VS content, as expected. The positive correlation between the VS and the BMP test (r=0.67) suggests that the first could be used as a primary indicator of biogas potential of waste samples. Nevertheless, it should be validated against the BMP test because, occasionally, the VS content does not equate to the biogas production. This was mainly due to the paper content of the samples which also correlates positively (r=0.77) with the BMP biogas production. The EHT results showed a higher correlation with the BMP test (r=0.91) than in previous studies which used a wider mixture of enzymes containing cellulase, hemicellulase and carbohydrase. This finding positions the EHT as a quick assessing method for the biodegradability of waste samples in future sample regimes.

High metal reactivity and environmental risks at a site contaminated by glass waste

This study addresses the reactivity and risks of metals (Ba, Cd, Co, Cr, Cu, Ni, Pb, Zn, As and Sb) at a Swedish site with large glass waste deposits. Old glassworks sites typically have high total metal concentrations, but as the metals are mainly bound within the glass waste and considered relatively inert, environmental investigations at these kinds of sites are limited. In this study, soil and landfill samples were subjected to a sequential chemical extraction procedure. Data from batch leaching tests and groundwater upstream and downstream of the waste deposits were also interpreted. The sequential extraction revealed that metals in <2 mm soil/waste samples were largely associated with geochemically active fractions, indicating that metals are released from pristine glass and subsequently largely retained in the surrounding soil and/or on secondary mineral coatings on fine glass particles. From the approximately 12,000 m3 of coarse glass waste at the site, almost 4000 kg of Pb is estimated to have been lost through corrosion, which, however, corresponds to only a small portion of the total amount of Pb in the waste. Metal sorption within the waste deposits or in underlying soil layers is supported by fairly low metal concentrations in groundwater. However, elevated concentrations in downstream groundwater and in leachates of batch leaching tests were observed for several metals, indicating on-going leaching. Taken together, the high metal concentrations in geochemically active forms and the high amounts of as yet uncorroded metal-rich glass, indicate considerable risks to human health and the environment.

Mass balance evaluation of polybrominated diphenyl ethers in landfill leachate and potential for transfer from e-waste

Previous research on brominated flame retardants (BFRs), including polybrominated diphenyl ethers (PBDEs) has largely focussed on their concentrations in the environment and their adverse effects on human health. This paper explores their transfer from waste streams to water and soil. A comprehensive mass balance model is developed to track polybrominated diphenyl ethers (PBDEs), originating from e-waste and non-e-waste solids leaching from a landfill. Stepwise debromination is assumed to occur in three sub-systems (e-waste, aqueous leachate phase, and non-e-waste solids). Analysis of landfill samples and laboratory results from a solid-liquid contacting chamber are used to estimate model parameters to simulate an urban landfill system, for past and future scenarios. Sensitivity tests to key model parameters were conducted. Lower BDEs require more time to disappear than high-molecular weight PBDEs, since debromination takes place in a stepwise manner, according to the simplified reaction scheme. Interphase mass transfer causes the decay pattern to be similar in all three sub-systems. The aqueous phase is predicted to be the first sub-system to eliminate PBDEs if their input to the landfill were to be stopped. The non-e-waste solids would be next, followed by the e-waste sub-system. The model shows that mass transfer is not rate-limiting, but the evolution over time depends on the kinetic degradation parameters. Experimental scatter makes model testing difficult. Nevertheless, the model provides qualitative understanding of the influence of key variables.