Leachate Constituents Research Articles

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

Elevated per- and polyfluoroalkyl substance (PFAS) concentrations have been reported in municipal solid waste (MSW) landfill leachate with higher levels in wet and warmer subtropical climates. Information about landfill leachate characteristics is much more limited in tropical climates. In this study, 20 landfill leachate samples were collected from three MSW landfills on the tropical island of Puerto Rico and results were compared against landfills nationally and within Florida, USA. The samples collected in Puerto Rico underwent physical-chemical analysis, as well as a quantitative analysis of 92 PFAS. Samples described in this study include discrete leachate types, such as leachate, gas condensate, and leachate which has undergone on-site treatment (e.g., RO treatment, phytoremediation, lagoons). A total of 51 PFAS were detected above quantitation limits, including perfluorohexylphosphonic acid, a perfluoroalkyl acid (PFAA) which has not been reported previously in landfill leachate. ∑PFAS concentrations in this study (mean: 38,000 ng L−1), as well as concentrations of individual PFAS, are significantly higher than other reported MSW landfill leachate concentrations. The profiles of leachates collected from on-site treatment systems indicate possible transformation of precursor PFAS as a result of treatment processes – oxidizing conditions, for example, may facilitate aerobic transformation, increase the concentrations of PFAAs, and possibly increase the apparent ∑PFAS concentration. Extreme climate events, including rising temperatures and more frequent hurricanes, have placed additional strain on the solid waste management infrastructure on the island – adding complexity to an already challenging PFAS management issue. As concern grows over PFAS contamination in drinking water, these findings should inform solid waste and leachate management decisions in order to minimize PFAS emissions in island environments.

Characterisation of high burnup spent mixed oxide fuel after leaching at hyperalkaline pH in a reducing environment

Microstructural investigations of a Zircaloy-4 clad mixed oxide fuel rod segment with a burnup of 50.3 GWd/tHM after exposure to a synthetic young cementitious water at a hyperalkaline pH of 13.7(2) under reducing atmosphere for about 3.5 years were conducted. A deposit on surfaces exposed to the leachate was observed and attempts were made to identify its composition. Initial scanning electron microscopy/energy dispersive X-ray spectroscopy results indicate that it contains several leachate constituents, as well as Zr and Ti. The presence of Ti indicates corrosion of the autoclave liner during the leaching experiment. Surfaces which were not directly exposed to the leachate revealed additional features, such as distinct ε-particles. Remarkably, these could not be identified on surfaces exposed to the leachate, which may indicate that dissolution of the ε-particles took place as well.Graphical abstract

Leachate indicators of an elevated temperature landfill

Elevated temperature landfills (ETLFs) are municipal solid waste (MSW) landfills that have been impacted by subsurface exothermic reactions (SERs) and display unusual gas and leachate composition. Leachate quantity and quality data were analyzed to identify indicators of a SER at an ETLF in Ohio, USA. ETLF leachate generation increased from 2.04 to 14.4 m3/hectare-day (218 to 1,539 gallons/acre-day), peaking 16 months after the reaction was first noticed. The leachate generation rate for this ETLF remains about two times greater than the average Ohio MSW landfill. Several general parameters such as pH, electrical conductivity (EC), and total dissolved solids (TDS) remain impacted 5 years later. Similarly, metals such as arsenic, iron, calcium, potassium, and magnesium have increased in concentration. Volatile organic compounds (VOCs) behavior was less consistent as a group of chemicals. Increases of VOCs such as acetone, benzene, and methyl ethyl ketone (MEK) also increased. Importantly, in one year, benzene exceeded its toxicity characteristic threshold meaning the leachate was a hazardous waste, substantially increasing treatment and disposal costs. It is not clear if the VOCs are produced directly by the SER or if they are an indicator that microbial processes -which would otherwise consume them- have been disrupted. ETLFs likely do not all undergo the same exothermic reaction(s) and, unlike the analysis of landfill gas composition, temporal changes in leachate constituents’ concentrations may be more important than comparing to absolute values.

Nanoparticle-specific and chemical-specific effects of tire wear particle leachate on amphibian early life stages

Tire wear particles (TWP) have been identified as a potentially toxic form of plastic in the environment. The exact mechanisms of toxicity of TWP are poorly understood, especially the possibility of specific toxicity pathways due to nanoparticles and leached chemicals. The amphibian Silurana tropicalis was exposed to stock dispersions of different fractions of TWP leachate (nanoparticles and leached chemicals; leached chemicals; nanoparticles) during its early development for 60 h and 9 days, and endpoints such as mortality, malformations and behavior were recorded. In the 60-h exposure, individuals were exposed to treatments ranging from 0 to 100% of the stock dispersions. The nanoparticle fraction caused a significant decrease in larval survival at all concentrations. The proportion of malformed tadpoles and tail abnormalities were impacted by all fractions, but fractions containing leached chemicals exhibited more head, gut, and edema malformations. For the 9-day exposure, individuals were exposed to treatments ranging from 0 to 10% of the stock dispersions. At almost all concentrations, survival was significantly reduced. Tadpoles exposed to the nanoparticle fraction had significantly larger brains. Tadpoles in fractions containing leached chemicals swam significantly less in the 10% treatment. These results reveal particle-specific and chemical-specific effects of TWP leachate which may have negative repercussions at the population level. Environmental implicationsThe mechanisms of toxicity of tire wear particle leachate are currently poorly understood, especially in freshwater organisms. Our study sheds light on the differing toxicities of the nanoparticulate and dissolved chemical constituents of tire wear particle leachate on a highly relevant model amphibian, Silurana tropicalis. Leached tire wear chemicals, tire wear nanoparticles, and their mixture affected survival and physiologically relevant endpoints of the larval amphibian such as malformations, swimming behavior and brain morphometry, which can lead to adverse impacts at the population and ecosystem levels. The physiological impacts varied for the different tire wear leachate fractions, suggesting that the environmental impacts may vary with the weathering conditions and the dispersal patterns of dissolved and nanoparticulate species of tire wear leachate

Feasibility of tubing two-phase bioreactors for biological treatment of high toxicity landfill leachate

This study describes the performance of a two-phase tubing bioreactor operated with an extractive polymeric membrane able to selectively transfer and biologically remove the toxic fraction of an industrial/hazardous waste landfill leachate. An additional feature of this bioreactor is the separation of the biomass from the polluted stream with consequent marked reduction of the inhibitory/toxic effect exerted by leachate constituents. Process performance has been optimized for decreasing HRTs, from 5.5 to 1.9 h, and step-increased OLRs, from 300 to 900 gCOD/L d with excellent removal efficiencies (88–99%). Removal rates of toxic chemicals, represented by phenolic compounds, as well as mass transfer and biomass activity, were not negatively affected by severe loading conditions. On the contrary, the trend of oxygen consumption rate suggested increased activity of the microorganisms with raised loads. Furthermore, biodegradation efficiency of 90% has been observed by evaluating the final mass balance after washing the polymer, which retained only 1.5% of totally fed phenolics. This work provided reliable results to conclude that the tested tubing bioreactor is an effective and stable treatment technology ready for commercial application, with evident operating advantages and the possibility to recover concurrently other valuable leachate constituents as VFAs and ammonia.

No Butts on the Beach: Aquatic Toxicity of Cigarette Butt Leachate Chemicals.

Toxic pollutants leaching from littered cigarette butts (CB) raise environmental impact concerns. The US Food and Drug Administration (FDA) is required to assess the environmental impacts of its tobacco regulatory actions per the US National Environmental Policy Act (NEPA). We determined the chemical constituents in CB leachate through analyses of 109 field-collected CB and literature compilation and characterized their ecotoxicity to aquatic organisms. One-third of the 98 identified CB leachate chemicals were very toxic and 10% were toxic to aquatic organisms due to acute and chronic toxicity. Polycyclic aromatic hydrocarbons, metals, phthalates, nicotine and volatile organic compounds were the most hazardous CB leachate chemicals for aquatic organisms. Of the 98 CB leachate chemicals, 25 are included in FDA's list of harmful or potentially harmful constituents in tobacco products and tobacco smoke. Our study quantifies CB leachate constituents, characterizes their ecological hazard and identifies chemicals of concern. Thus, it aids in evaluating the environmental impacts of tobacco products per NEPA requirements. These results provide important information for strategies to prevent and reduce CB litter (eg, awareness programs, litter laws enforcement), thereby reducing environmental hazards from CB toxicants.

Numerical modeling of clogging of landfill leachate collection systems with co-disposal of municipal solid waste (MSW) and incinerator ash

The influence of co-disposal of municipal solid waste (MSW) and incinerator ash used as daily cover on the clogging of leachate collection systems (LCSs) from landfills is examined. The “BioClog” model is used to simulate the fate and transport of the nine leachate constituents most responsible for clogging the LCSs as they move through the porous media. It then calculates the thicknesses of five films that attach to the porous media and the effect of this clog mass–volume on the porosity and hydraulic conductivity of the granular material. Then it models the consequent growth in the leachate mound with increasing clog mass over time until the service life of the LCS is reached. The modeling shows that the concentrated source of leachable minerals in the incinerator ash accelerates the clogging rate and reduces the service life of the LCSs compared to inert daily cover. If an LCS is not designed to accommodate these higher concentrations of cations in the influent leachate during the landfill operating period, the ash can significantly reduce the LCS service life. Means of extending LCS service life are discussed. A practical technique is also utilized to estimate the service life of LCSs with conservative and reasonable agreement with BioClog.

Effects of photochemical and microbiological changes in terrestrial dissolved organic matter on its chemical characteristics and phytotoxicity towards cyanobacteria

Previous studies have shown that under laboratory conditions, dissolved organic matter (DOM) leached from plants can be differentially more phytotoxic to cyanobacteria, compared to green algae. This study examined how DOM source and transformation processes (microbial and photochemical) affect its chemical composition and phytotoxicity towards a cultured species of cyanobacteria (Raphidiopsis raciborskii) using a factorial experimental design. To complement cyanobacterial bioassays, the chemical composition and associated changes in DOM were determined using spectroscopic (nuclear magnetic resonance (NMR) and absorbance) and elemental analyses. Sunlight exposed DOM from leaves of the terrestrial plants, Casuarina cunninghamiana and Eucalyptus tereticornis had the most phytotoxic effect compared to DOM not exposed to sunlight. This phytotoxic DOM was characterised by relatively low nitrogen content, containing highly coloured and relatively high molecular mass constituents. Both mixed effect model and PCA approaches to predict inhibition of photosynthetic yield indicated phytotoxicity could be predicted (P < 0.001) based upon the following parameters: C: N ratio; gilvin, and lignin-derived phenol content of DOM. Parallel proton-detected 1D and 2D NMR techniques showed that glucose anomers were the major constituents of fresh leachate. With ageing, glucose anomers disappeared and products of microbial transformation appeared, but there was no indication of the appearance of additional phytotoxic compounds. This suggests that reactive oxygen species may be responsible, at least partially, for DOM phytotoxicity. This study provides important new information highlighting the characteristics of DOM that link with phytotoxic effects.

Re-evaluation of sulfate radical based–advanced oxidation processes (SR-AOPs) for treatment of raw municipal landfill leachate

Sulfate radical (SO4-) -based advanced oxidation processes (SR-AOPs) have proven effective for simultaneously removing refractory dissolved organic matter (DOM) and ammonia in municipal landfill leachates. However, the knowledge on the competition of leachate DOM and ammonia for SO4-, the utilization efficiency of persulfate, as well as the reaction pathways and final products of ammonia oxidation during the SR-AOP treatment remains little known, thereby leading to a lack of a comprehensive evaluation of the emerging leachate treatment technology. The objective of this study was to further investigate the performance of a thermally activated persulfate system for treatment of a mature landfill leachate and re-evaluate the benefits and restrictions of SR-AOPs for leachate treatment. The laboratory experimental results showed that removal patterns of chemical oxygen demand (COD) and ammonia relied heavily upon the dose of persulfate that could be thermally activated to produce reactive sulfate radicals, reflecting the competition of leachate DOM, ammonia, and non-target leachate constituents for SO4-. The utilization efficiency of the added persulfate could be more efficiently utilized for removing the two target leachate pollutants at a lower persulfate dose, whereas more persulfate was wasted due to the reactions with non-target leachate constituents (e.g. Cl− and CO32−) and/or self-decomposition with the increasing persulfate dose. During the treatment, ammonia was oxidized, via the direct attack of SO4- and/or by molecular chlorine produced from the reactions of chloride and sulfate radicals, into nitrate and nitrogen gas, while nitrite was not detected. Of importance, this study highlighted three potentially negative impacts of SR-AOPs on the quality of treated leachate, including accumulation of total dissolved solids, the production of undesirable nitrate, and the pH decrease due to the continuous formation of hydrochloric acid. Therefore, the three issues should be carefully evaluated when a SR-AOP is selected for leachate treatment. Because these impacts become less pronounced with a decreasing persulfate dose, SR-AOPs as a pre-treatment, which is achieved at a relatively low persulfate dose, may be an appropriate option for the SR-AOP application to leachate treatment.

Exploring the fate and oxidation behaviors of different organic constituents in landfill leachate upon Fenton oxidation processes using EEM-PARAFAC and 2D-COS-FTIR

In this work, the changes of different organic constituents in landfill leachate were tracked in Fenton oxidation processes with different operation parameters including H2O2 doses, pH, and the ratios of [H2O2]/[Fe] via fluorescence excitation emission matrix – parallel factor analysis (EEM-PARAFAC) and two-dimensional correlation spectroscopy (2D-COS). One tryptophan-like (C1), one fulvic-like (C2), and one humic-like (C3) components were identified in the leachates. The removal behaviors of the individual fluorescent components were dependent upon the operation conditions, suggesting the existence of unique characteristics with respect to the responses to the oxidation mechanisms, which were likely altered by different operation conditions. For all tested conditions, a greater extent of removal was consistently found for C3 versus C1 and C2 except for the relatively high pH ranges (>6.0), in which C2 presented the highest removal rates. 2D-COS combined with synchronous fluorescence spectra exhibited the preferential oxidation sequence in the order of C3 > C1 > C2 with higher H2O2 doses. 2D-COS coupled with Fourier transform infrared (2D-COS-FTIR) showed that aromatic functional groups were initially oxidized, followed by the removal of carboxylic groups and the formation of inorganic functional groups and aldehyde or ketonic groups. Hetero 2D-COS maps further revealed the close association between the aromatic groups and C3, and between the carboxylic groups and C1. This study utilizing 2D-COS provided new insights into the dynamic behavior of heterogeneous landfill leachate in Fenton oxidation processes under varying operation conditions.

Characterization of organic components in leachables from Bulgarian lignites by spectroscopy, chromatography and reductive pyrolysis

Lignites from Thrace- and Sofia- coal basins, i.e. “Maritsa-East” and “Stanjanci” mines, were subjected to aqueous sequential extraction at 25°C during 10weeks. Each 7days leachates were separated and pH and conductivity were measured. According to the extraction curves μS vs. time two portions were prepared, enriched in salts, extracts from the first two weeks (“front” of the elution) and in organic matter, extracts from the rest of time (“tail” of the elution curve). Combined freeze-dried extracts were characterized by yields, technical and elemental analyses. They were studied by X-ray photoelectron spectroscopy (XPS) and Infrared spectroscopy (IR). According to XPS spectra the main species on the leachate surfaces were carbon atoms in aromatic and aliphatic structures, 48–53at. % from the total C1s signal. The intensive N1s signal at 400eV was assigned to pyrroles and amines (1–3at. %). The most abundant sulphur form was inorganic sulphates while intensities for the other ones were <1%. Respectively, the sulphatic sulphur content (13.6%) determined for Maritsa leachate was almost seven times higher than the same sulphur for Stanjanci leachate. FTIR spectra gave evidences for oxygen-containing functional groups, i.e. COOH groups in benzene carboxylic acids and their derivatives, in short-chain aliphatic fatty acids and for polyols. The appearance of mineral matter, mainly gypsum and kaolinite, made equivocal the IR spectra interpretation.Acetone soluble portions of “tail” leachates have represented relatively small parts of the organic matter (340mg/kg Maritsa East and 80mg/kg Stanjianci lignite) but have assigned reliable evidences for the polar constituents of leachates. Linear fatty acids, nC12–nC32, nC16max, n-alcohols, benzoic acids, i.e. hydroxy-, methoxy-, phthalic acids, were highly abundant. Sterols, stanols, ketosterols were present in both extracts. Phthalates were recognizable as well.AP-TPR-TD-GC/MS technique has proved the presence of phenols, PAHs and heteroatom containing components in leachates flue gases. From an environmental viewpoint it seems that the identified compounds do not represent an acute toxic risk. However, N-containing compounds could raise concerns and further attention is needed to be focused on them.

Assessing the role of bed sediments in the persistence of red mud pollution in a shallow lake (Kinghorn Loch, UK)

Red mud is a by-product of alumina production. Little is known about the long-term fate of red mud constituents in fresh waters or of the processes regulating recovery of fresh waters following pollution control. In 1983, red mud leachate was diverted away from Kinghorn Loch, UK, after many years of polluting this shallow and monomictic lake. We hypothesised that the redox-sensitive constituents of red mud leachate, phosphorus (P), arsenic (As) and vanadium (V), would persist in the Kinghorn Loch for many years following pollution control as a result of cycling between the lake bed sediment and the overlying water column. To test this hypothesis, we conducted a 12-month field campaign in Kinghorn Loch between May 2012 and April 2013 to quantify the seasonal cycling of P, As, and V in relation to environmental conditions (e.g., dissolved oxygen (DO) concentration, pH, redox chemistry and temperature) in the lake surface and bottom waters. To confirm the mechanisms for P, As and V release, a sediment core incubation experiment was conducted using lake sediment sampled in July 2012, in which DO concentrations were manipulated to create either oxic or anoxic conditions similar to the bed conditions found in the lake. The effects on P, As, and V concentrations and species in the water column were measured daily over an eight-day incubation period.Phosphate (PO4-P) and dissolved As concentrations were significantly higher in the bottom waters (75.9 ± 30.2 μg L−1 and 23.5 ± 1.83 μg L−1, respectively) than in the surface waters (12.9 ± 1.50 μg L−1 and 14.1 ± 2.20 μg L−1, respectively) in Kinghorn Loch. Sediment release of As and P under anoxic conditions was confirmed by the incubation experiment and by the significant negative correlations between DO and P and As concentrations in the bottom waters of the lake. In contrast, the highest dissolved V concentrations occurred in the bottom waters of Kinghorn Loch under oxic conditions (15.0 ± 3.35 μg L−1), with the release from the bed sediment apparently being controlled by a combination of competitive ion concentrations, pH and redox conditions.

Estimating landfill leachate BOD and COD based on rainfall, ambient temperature, and waste composition: Exploration of a MARS statistical approach

Abstract Municipal solid waste generation is increasing rapidly globally. Increasing storage of waste in landfills means increased production of liquid landfill leachate. Leachate contains organic and inorganic pollutants which must be treated to reduce its potential impact on surrounding water supplies. To design landfill leachate treatment, its chemical composition must be known; however, the composition of leachate can vary widely depending on waste composition. Measuring leachate constituents can be expensive and time consuming, and is not possible for a landfill under construction. A global model able to forecast leachate quality parameters based on a landfill’s waste composition, ambient temperature, and rainfall rate is critically needed. This research represents a first step in development of such a model. Laboratory data on leachate biochemical and chemical oxygen demand (BOD, COD) was collected as functions of waste composition (food, paper, yard, textile), temperature (70, 85, 100 °F), and rainfall rates (2, 6, 12 mm/day), according to a statistical experimental design. Multivariate Adaptive Regression Splines (MARS) models were developed for BOD and COD, with adjusted- R 2 of 0.92 and 0.95, respectively. This exploratory research demonstrated the usefulness of MARS in capturing complex relationships among waste composition, temperature, and rainfall rate in order to forecast leachate quality parameters over time.

Low Technological Biological Treatment of Source Separated Waste in a Biocell

In 2009 the Norwegian government banned biodegradable waste in landfills to mitigate climate gas production. To be able to stabilize source separated waste before landfilling a constructed biocell has been tested during a four year period. The research is part of a pilot project organized by Avfall Norge. A total amount of 12 000 tons of waste from both industry and households were embedded in the biocell. Before loading, the waste fractions were characterized both in macro and micro scale. Anaerobic testing in lab scale documented the methane potential in different waste fractions. Especially car fluff contained toxic components which suppressed biodegradation. To avoid greenhouse gas leakage the biocell was constructed as a closed system with synthetic capping and gas wells coupled to a compressor. While the biogas was flared the leachate was collected and recycled. Leachate contains both nutrients and DOC which is supposed to increase the biological activity. During the first part of the test period the BOD/COD was above 0.5 before it declined. In addition both inorganic and organic environmental harmful components were analyzed in the leachate. Levels of heavy metal decreased during treatment. The methane production was detected on-line with IR. Both the production and gas phase concentration varied during the test period. A total of five gas wells were positioned at different levels in the biocell. Only one of them produced biogas for a considerable period. This presentation will focus on biocell construction and waste degradation related to variation in leachate constituents as a function of time.

Variation of the phytotoxicity of municipal solid waste incinerator bottom ash on wheat (Triticum aestivum L.) seed germination with leaching conditions.

Municipal solid waste incinerator bottom ash (MSWIBA) has long been regarded as an alternative building material in the construction industry. However, the pollutants contained in the bottom ash could potentially leach out and contaminate the local environment, which presents an obstacle to the reuse of the materials. To evaluate the environmental feasibility of using MSWIBA as a recycled material in construction, the leaching derived ecotoxicity was assessed. The leaching behavior of MSWIBA under various conditions, including the extractant type, leaching time, liquid-to-solid (L/S) ratio, and leachate pH were investigated, and the phytotoxicity of these leachates on wheat (Triticum aestivum L.) seed germination was determined. Moreover, the correlation between the germination index and the concentrations of various chemical constituents in the MSWIBA leachates was assessed using multivariate statistics with principal component analysis and Pearson's correlation analysis. It was found that, heavy metal concentrations in the leachate were pH and L/S ratio dependent, but were less affected by leaching time. Heavy metals were the main pollutants present in wheat seeds. Heavy metals (especially Ba, Cr, Cu and Pb) had a substantial inhibitory effect on wheat seed germination and root elongation. To safely use MSWIBA in construction, the potential risk and ecotoxicity of leached materials must be addressed.

Trace metal distribution and mobility in drill cuttings and produced waters from Marcellus Shale gas extraction: Uranium, arsenic, barium

Development of unconventional shale gas wells can generate significant quantities of drilling waste, including trace metal-rich black shale from the lateral portion of the drillhole. We carried out sequential extractions on 15 samples of dry-drilled cuttings and core material from the gas-producing Middle Devonian Marcellus Shale and surrounding units to identify the host phases and evaluate the mobility of selected trace elements during cuttings disposal. Maximum whole rock concentrations of uranium (U), arsenic (As), and barium (Ba) were 47, 90, and 3333mgkg−1, respectively. Sequential chemical extractions suggest that although silicate minerals are the primary host for U, as much as 20% can be present in carbonate minerals. Up to 74% of the Ba in shale was extracted from exchangeable sites in the shale, while As is primarily associated with organic matter and sulfide minerals that could be mobilized by oxidation. For comparison, U and As concentrations were also measured in 43 produced water samples returned from Marcellus Shale gas wells. Low U concentrations in produced water (<0.084–3.26μgL−1) are consistent with low-oxygen conditions in the wellbore, in which U would be in its reduced, immobile form. Arsenic was below detection in all produced water samples, which is also consistent with reducing conditions in the wellbore minimizing oxidation of As-bearing sulfide minerals.Geochemical modeling to determine mobility under surface storage and disposal conditions indicates that oxidation and/or dissolution of U-bearing minerals in drill cuttings would likely be followed by immobilization of U in secondary minerals such as schoepite, uranophane, and soddyite, or uraninite as conditions become more reducing. Oxidative dissolution of arsenic containing sulfides could release soluble As in arsenate form under oxic acidic conditions. The degree to which the As is subsequently immobilized depends on the redox conditions along the landfill flow path. The results suggest that proper management of drill cuttings can minimize mobilization of these metals by monitoring and controlling Eh, pH and dissolved constituents in landfill leachates.

Effect of leachate composition on the long-term performance of a HDPE geomembrane

Aging of the same geomembrane immersed in the same four synthetic municipal solid waste leachates tested by Rowe et al. (2008) for 2.65 years is continued for an additional 6.5 years (i.e., providing data over more than 9 years of aging). The additional data is used to (a) update the initial estimates for antioxidant depletion stage, and (b) investigate the effect of leachate constituents on the timing and magnitude of the changes in the physical properties of the geomembrane. While all the examined leachates had surfactant and trace metals in common, reduced Leachate 1 (full leachate) had salts and volatile fatty acids (VFAs), Leachate 2 was not reduced and had neither salts nor VFAs, reduced Leachate 3 had salts, reduced Leachate 4 had VFAs, and Leachate 5 was similar to Leachate 2 except that it was reduced. Incubation in all leachates gave very similar predictions of the antioxidant depletion stage, however, the salts in Leachates 1 and 3 are shown to have the largest effect on the geomembrane mechanical properties, especially stress-crack resistance, resulting in a shorter time to nominal failure than for leachates without salts. Furthermore, reduced Leachates 1 and 3 showed faster degradation in stress-crack resistance than Leachate 2 which was not reduced and without salts. Arrhenius modeling is used to extrapolate the time to nominal failure (i.e., a reduction in stress-crack resistance to 150 h) at a range of temperatures.

Longitudinal data analysis in support of functional stability concepts for leachate management at closed municipal landfills

Landfill functional stability provides a target that supports no environmental threat at the relevant point of exposure in the absence of active control systems. With respect to leachate management, this study investigates “gateway” indicators for functional stability in terms of the predictability of leachate characteristics, and thus potential threat to water quality posed by leachate emissions. Historical studies conducted on changes in municipal solid waste (MSW) leachate concentrations over time (longitudinal analysis) have concentrated on indicator compounds, primarily chemical oxygen demand (COD) and biochemical oxygen demand (BOD). However, validation of these studies using an expanded database and larger constituent sets has not been performed. This study evaluated leachate data using a mixed-effects regression model to determine the extent to which leachate constituent degradation can be predicted based on waste age or operational practices. The final dataset analyzed consisted of a total of 1402 samples from 101MSW landfills. Results from the study indicated that all leachate constituents exhibit a decreasing trend with time in the post-closure period, with 16 of the 25 target analytes and aggregate classes exhibiting a statistically significant trend consistent with well-studied indicators such as BOD. Decreasing trends in BOD concentration after landfill closure can thus be considered representative of trends for many leachate constituents of concern.

Characterization and treatment of organic constituents in landfill leachates that influence the UV disinfection in the publicly owned treatment works (POTWs)

Landfill leachates strongly quench UV light. When discharged to POTWs, leachates can interfere with UV disinfection. To investigate the UV quenching problem of landfill leachates, a variety of landfill leachates with a range of conditions were collected and characterized. The UV blocking component was found to be resistant to biological degradation so they pass through wastewater treatment plants and impact the subsequent UV disinfection system. Leachate samples were fractionated into humic acids (HAs), fulvic Acids (FAs) and hydrophilic (Hpi) fractions to investigate the source of UV absorbing materials. Results show that for all leachates examined, the specific UV254 absorbance (SUVA254) of the three fractions follows: HA>FA>Hpi. However, the overall UV254 absorbance of the Hpi fraction was important because there was more hydrophilic organic matter than humic or fulvic acids. The size distribution was also investigated to provide information about the potential for membrane treatment. It was found that the size distribution of the three fractions follows: HA>FA>Hpi. This indicates that membrane separation following biological treatment is a promising technology for removal of humic substances from landfill leachates. Leachate samples treated in this manner could meet the UV transmittance requirement of the POTWs.

An Analysis of Leachate Constituents and Pathogen Destruction in Deer Mortality Static Windrow Composting

Approximately 1.1 million deer–vehicle collisions occur in the United States each year. The predominant methods of disposing of these carcasses (landfill and burial) have several costly disadvantages, including long travel distances to landfills, increasing landfill restrictions, and lack of viable burial areas. Some states have found static compost windrows to be an easy and cost-effective carcass management technique. This type of composting involves the construction of passively aerated static piles, which do not require the materials turning needed with more traditional composting methods. In this study, deer mortality static compost windrows were monitored for 1 year. Windrows were analyzed for pathogen destruction and the degree to which underlying soil filtered leachate contaminants. In response to high windrow temperatures, indicator pathogens Escherichia coli and Salmonella were reduced by 99.99 % the first sampling day (day 7) and ascarids were deemed non-viable by day 77. Soil filtration of leachate was effective in reducing concentrations of ammonia, chloride, and total organic carbon. Nitrate, a contaminant of particular regulatory concern, had an estimated mass contaminant loss of 2.1 kg/ha, compared to the estimated 9 to 50 kg/ha loss from fertilizer application of common agronomic crops. Results of this study indicate that with properly constructed static compost windrows, (1) high temperatures effectively destroy indicator pathogens; (2) the natural filtration of leachate through soil reduces deer mortality contaminant concentrations; and (3) the low volume of leachate (i.e., two percent of the precipitation that fell on windrows) results in nominal losses of nitrate and other contaminants.