Young Landfill Research Articles

Comparison of Field Measurements to Methane Emissions Models at a New Landfill.

Estimates of methane emissions from landfills rely primarily on models due to both technical and economic limitations. While models are easy to implement, there is uncertainty due to the use of parameters that are difficult to validate. The objective of this research was to compare modeled emissions using several greenhouse gas (GHG) emissions reporting protocols including: (1) Intergovernmental Panel on Climate Change (IPCC); (2) U.S. Environmental Protection Agency Greenhouse Gas Reporting Program (EPA GHGRP); (3) California Air Resources Board (CARB); and (4) Solid Waste Industry for Climate Solutions (SWICS), with measured emissions data collected over three calendar years from a young landfill with no gas collection system. By working with whole landfill measurements of fugitive methane emissions and methane oxidation, the collection efficiency could be set to zero, thus eliminating one source of parameter uncertainty. The models consistently overestimated annual methane emissions by a factor ranging from 4-31. Varying input parameters over reasonable ranges reduced this range to 1.3-8. Waste age at the studied landfill was less than four years and the results suggest the need for measurements at additional landfills to evaluate the accuracy of the tested models to young landfills.

Effect of bioavailability on the fate of hydrophobic organic compounds and metal in treatment of young landfill leachate by membrane bioreactor

Complex dissolved organic matter (DOM) present in landfill leachate provides reliable media for adsorption of highly hydrophobic contaminants, such as Di 2-ethyl hexyl phthalate (DEHP). In this research, the feasibility of submerged membrane bioreactor (SMBR) for treatment of landfill leachate (LFL) was determined. Later, the operating conditions were optimized for removal of DEHP, COD, NH4+ and PO43−, and finally the effect of bioavailability was examined by introduction of different concentrations of humic acid into the influent. The result revealed that presence of complex agglomerated organic compounds increased the removal efficiency of DEHP and COD, even though DEHP biodegradation rate in sludge dramatically decreased (from 58.8% to 12.8%). MBR retention of different metals in the absence and in the presence of recalcitrant DOM was also studied. Like DEHP, ternary interaction between metals, DOM, and sludge play a pivotal role in their removal efficiency and their concentration in sludge.

Management of landfill leachate: The legacy of European Union Directives

Landfill leachate is the product of water that has percolated through waste deposits and contains various pollutants, which necessitate effective treatment before it can be released into the environment. In the last 30years, there have been significant changes in landfill management practices in response to European Union (EU) Directives, which have led to changes in leachate composition, volumes produced and treatability. In this study, historic landfill data, combined with leachate characterisation data, were used to determine the impacts of EU Directives on landfill leachate management, composition and treatability. Inhibitory compounds including ammonium (NH4-N), cyanide, chromium, nickel and zinc, were present in young leachate at levels that may inhibit ammonium oxidising bacteria, while arsenic, copper and silver were present in young and intermediate age leachate at concentrations above inhibitory thresholds. In addition, the results of this study show that while young landfills produce less than 50% of total leachate by volume in the Republic of Ireland, they account for 70% of total annual leachate chemical oxygen demand (COD) load and approximately 80% of total 5-day biochemical oxygen demand (BOD5) and NH4-N loads. These results show that there has been a decrease in the volume of leachate produced per tonne of waste landfilled since enactment of the Landfill Directive, with a trend towards increased leachate strength (particularly COD and BOD5) during the initial five years of landfill operation. These changes may be attributed to changes in landfill management practices following the implementation of the Landfill Directive. However, this study did not demonstrate the impact of decreasing inputs of biodegradable municipal waste on leachate composition. Increasingly stringent wastewater treatment plant (WWTP) emission limit values represent a significant threat to the sustainability of co-treatment of leachate with municipal wastewater. In addition, the seasonal variation in leachate production poses a risk to effective co-treatment in municipal WWTPs, as periods of high leachate production coincide with periods of maximum hydraulic loading in WWTPs.

Analysis of microbial community structure and composition in leachates from a young landfill by 454 pyrosequencing.

Microorganisms are responsible for degrading the raw leachate generated in sanitary landfills, extracting the soluble fraction of the landfill waste and biotransforming organic matter and toxic residues. To increase our understanding of these highly contaminated ecosystems, we analyzed the microbial communities in the leachate produced by three landfill cells of different ages. Using high-throughput 454 pyrosequencing of the 16S rRNA gene, we describe the structure of the leachate communities and present their compositional characteristics. All three communities exhibited a high level of abundance but were undersampled, as indicated by the results of the rarefaction analysis. The distribution of the taxonomic operational units (OTUs) was highly skewed, suggesting a community structure with a few dominant members that are key for the degradation process and numerous rare microorganisms, which could act as a resilient microorganism seeder pool. Members of the phylum Firmicutes were dominant in all of the samples, accounting for up to 62% of the bacterial sequences, and their proportion increased with increasing landfill age. Other abundant phyla included Bacteroidetes, Proteobacteria, and Spirochaetes, which together with Firmicutes comprised 90% of the sequences. The data illustrate a microbial community that degrades organic matter in raw leachate in the early stages, before the methanogenic phase takes place. The genera found fit well into the classical pathways of anaerobic digestion processes.

Monitoring transitory profiles of leachate humic substances in landfill aeration reactors in mesophilic and thermophilic conditions

The presence of humic substances (HS) in landfill leachate is of great interest because of their structural stability and potential toxicity. This study examined the effects of temperature and waste age on the transformation of HS during in situ aeration of bioreactor landfills. By establishing aerobic conditions, dissolved organic carbon (DOC) rapidly accumulated in the bioreactor leachate. Fractional analysis showed that the elevated concentration of humic acids (HAs) was primarily responsible for the increment of leachate strength. Further structural characterization indicated that the molecular weight (MW) and aromacity of HS were enhanced by aeration in conjunction with thermophilic temperature. Interestingly, elevation of HAs concentration was not observed in the aeration reactor with a prolonged waste age, as the mobility of HAs was lowered by the high MW derived from extended waste age. Based on these results, aeration may be more favorable in aged landfills, since dissolution of HAs could be minimized by the evolution to larger MW compared to young landfills. Moreover, increased operation temperature during aeration likely offers benefits for the rapid maturation of HS.

Change of surface and structure properties of cation exchange membrane in a microbial fuel cell

In this study, the two-chambered microbial fuel cell (MFC) was continuously long-term operated a young landfill leachate in order to evaluate the impact of cation exchange membrane (CEM) fouling on MFC performance. During the operation, the voltage output decreased sharply to almost zero and the voltage output was recovered completely after replacement of CEM, which implied that the voltage decrease was totally due to fouling of the CEM with the observations of attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy, the scanning electron microscopy (SEM) and long-term operation. The fouled membrane was washed with H2SO4 in order to recover the CEM via removing salts on membrane surface and the replacement of cations on the negatively charged sufonate sulfonate groups with the H+. After acid treatment, the current and power recoveries were only around 38% and 15%, respectively. The membrane was completely fouled again after one week of operation. Moreover, an alkali treatment with NaOH was applied in order to recover the CEM by removing organics on membrane surface. However, the alkali treatment had almost no effect on the fouled membrane depending on current output.

Effect of Temperature on Fenton oxidation of young landfill leachate: Kinetic Assessment and Sludge Properties

Treatment of young landfill leachate, collected from municipal solid waste site of city of Konya, was investigated by using the Fenton process. The leachate itself showed the characteristics of pH 7.25, COD 38.2 g L-1 and BOD5 22 g L-1. Ratio of BOD5 to COD with 0.58 indicates that leachate can be defined young. Fenton oxidation of landfill leachate was expressed in two-stage process, where a fast initial reaction (H2O2/Fe2+) was followed by a much slower one (H2O2/Fe3+). Overall kinetics can be described by a second-order rate equation followed by zero-order one. The kinetic studies were undertaken at the different temperatures and reaction rates increcesed by increasing temperature. The apparent kinetic constants at 303 K are k = 3.16 x10-3 L g-1 min-1 and k0 = 0,171 g L-1 min-1, respectively. Fenton reagents effectively degraded the leachate organics and most of the degradation was completed within 30 minutes for all temperatures. The performance of Fenton process was not only presented as a COD removal but also expressed as the amount of generated sludge and its properties. Sludge properties were revealed with Capillary Suction Time (CST) and Sludge Volume Index (SVI). The minimum CST value was obtained at the optimum molar ratio of 4.12 mol/mol and increasing temperature resulted in a positive effect on CST values. All SVI values were significantly low which indicates that sludge itself had good settling properties.

NEW DEVELOPMENTS IN THE RADIOLYSIS AND OZONOLYSIS OF LANDFILL LEACHATE

Old and young municipal landfill leachates samples were radiation processed with γ rays at a dose rate of 1 kGy/h. The fate of the soluble organic matter (humic substance) present in the leachates was followed by the chemical oxygen demand (COD) measurements. The radiolysis of old landfill leachate is a not an effective process in comparison to ozonolysis but can be enhanced significantly by the addition of H 2 O 2 to the old leachate prior to radiolysis and by bringing the pH of the leachate to zero. Some radiolyzed sample were further ozonized to reduce to the minimum possible the COD level. Young landfill leachate results instead more prone to radiolysis and less sensitive to ozonolysis than the old landfill leachate.

Enrichment of Anaerobic Ammonium Oxidation (Anammox) Bacteria for Biological Nitrogen Removal of Wastewater

Anaerobic ammonium oxidation (anammox) bacteria enrichment was explored for the potential application of ammonium rich wastewater removal. Samples of sludge from mature and young landfill leachate treatment plants were screened and used as inocula for anammox enrichment cultures. Enrichments were monitored for N-NH3, N-NO2- and N-NO3- to detect anammox potential activity. Six of the twelve enrichment cultures showed anammox activity after more than five months of enrichment period. All enrichment cultures that gave positive results were obtained from bottom part of sequencing batch reactor (SBR) lagoon indicating localization of anammox bacteria in anaerobic condition. Polymerase Chain Reaction (PCR) with specific primers targeting anammox and planctomycete were able to amplify the 16S rRNA sequence for anammox bacteria under PCR optimum condition. However, only three of six positive samples were successfully sequenced. DNA sequence analysis using NCBI (BLAST) and RDP showed that the anammox bacterial sequences of the investigated samples were identified as Candidatus Kuenenia stuttgartiensis with similarity of 100% (NCBI) and 99.3% (RDP).

Removal of bisphenol A and 17α-ethinyl estradiol by combined coagulation and adsorption using carbon nanomaterials and powdered activated carbon

In this study, combined coagulation–adsorption treatment using single-walled carbon nanotubes (SWCNTs), multiwalled carbon nanotubes (MWCNTs), and powdered activated carbon (PAC) was employed for the removal of endocrine disrupting chemicals (EDCs) from various water sources. Bisphenol A (BPA) and 17α-ethinyl estradiol (EE2) were the target EDCs used in this study. Natural surface water (BRW) was obtained from Broad River in Columbia, South Carolina. Synthetic seawater (SW) and brackish water (BW) were produced to reflect the typical composition observed in previously published literature. Synthetic landfill leachates were created to replicate the characteristics of leachate produced in young landfills (YLs) and old landfills (OLs). The adsorption capacity of the SWCNTs was greater for EE2 than for BPA for the majority of the aqueous solutions with the exceptions of BW and BRW. The adsorption capacity for BPA observed the following trend: BRW (log Kf=3.18)>SW (log Kf=3.01)>YL (log Kf=2.32)>BW (log Kf=1.96)>OL (log Kf=1.25), while the adsorption capacity of EE2 followed a different trend: SW (log Kf=3.41)>YL (log Kf=3.38)>BRW (log Kf=3.14)>OL (log Kf=2.09)>BW (log Kf=1.38). Molecular modeling was also conducted to determine the binding energies between the EDCs and the SWCNTs in both the gas phase and the liquid phase. The results showed higher binding energies between EE2 and the SWCNTs than between BPA and the SWCNTs in the gas phase and the aqueous phase, which support the higher removal of EE2 than BPA found using adsorption isotherm modeling. Jar testing was conducted with each adsorbent to simulate the combined coagulation–adsorption treatment process. The sole use of coagulation yielded small percentages of BPA removal (<10%) in each aqueous solution but higher percentages of EE2 removal. However, the removal percentages using the combined coagulation–adsorption process were similar to those achieved using only the adsorbent. In these processes, the SWCNTs outperformed the MWCNTs for each combination, while PAC often outperformed both the SWCNTs and the MWCNTs, with more than 90% removal of both BPA and EE2.

Could Landfill Leachate be a Resource for a Proper Environmental Management of Closed Landfills?

Copyright: © 2013 Del Moro G, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. The disposal of urban waste into landfill has been used for long time because of its relatively low cost. One of most important drawbacks associated to such a practice is related to managing the leachate that is generated when water passes through the waste. Leachate is, in fact, the aqueous effluent generated by rainwater percolation through wastes, biochemical processes in waste cells and the inherent water content of the waste itself [1-4]. The chemical composition of landfill leachate is influenced by a number of factors including seasonal precipitation,waste composition, and, mainly, the age of the landfill [5]. Consequently, the age of the landfill site is one of the main variables that affects the leachate characteristics [4,6]. Usually, young landfill leachates contain large amounts of biodegradable organic matter (i.e., volatile fatty acids) that decrease with increasing landfill age as a result of the anaerobic decomposition that takes place in the landfill site. As the content of volatile fatty acids decreases, organic matter in the leachates becomes dominated by refractory compounds, such as humicand fulvic acid-like ones with consequent reduction of the BOD/COD ratio [7]. In addition, ammonia concentration increases at higher landfill age as a result of the fermentation of organic matter containing proteins, being concentration higher than 2 g/L typical in old landfill leachates. Therefore, stabilized landfill leachates are more difficult to treat with respect to young ones. Although leachate composition may widely vary within the successive aerobic, acetogenic, methanogenic and stabilization stages of waste evolution, three types of leachates are commonly defined according to landfill age (recent, intermediate and old).

Bio-electrochemical post-treatment of anaerobically treated landfill leachate

Bio-electrochemical treatment of anaerobically pre-treated landfill leachate was investigated in batch and continuous-flow two-chambered microbial fuel cells (MFCs). A high strength young landfill leachate was pre-treated using an upflow anaerobic sludge blanket reactor and the effluent resembling medium-aged landfill leachate was fed to the anode chamber of MFCs. The highest maximum current and power densities achieved in continuous-flow MFC with hydraulic retention time (HRT) of five days were 525mA/m2 (8227mA/m3) and 158mW/m2 (2482mW/m3), respectively. Increase of HRT from one day to five days resulted in the occurrence of partial nitrification, where influent ammonia was converted into nitrite presumably due to the inhibitory effects of free ammonia. The maximum power and current densities obtained in this study were higher compared to other studies with similar leachate characteristics. The results of this study suggest that MFCs can be exploited as a polishing step for anaerobically pretreated landfill leachate.

Electricity generation from young landfill leachate in a microbial fuel cell with a new electrode material

This study aims at evaluating the performance of a two-chambered continuously fed microbial fuel cell with new Ti-TiO₂ electrodes for bioelectricity generation from young landfill leachate at varying strength of wastewater (1-50 COD g/L) and hydraulic retention time (HRT, 0.25-2 days). The COD removal efficiency in the MFC increased with time and reached 45 % at full-strength leachate (50 g/L COD) feeding. The current generation increased with increasing leachate strength and decreasing HRT up to organic loading rate of 100 g COD/L/day. The maximum current density throughout the study was 11 A/m² at HRT of 0.5 day and organic loading rate of 67 g COD/L/day. Coulombic efficiency (CE) decreased from 57 % at feed COD concentration of 1 g/L to less than 1 % when feed COD concentration was 50 g/L. Increase in OLR resulted in increase in power output but decrease in CE.

Effect of COD/SO ratio on anaerobic treatment of landfill leachate during the start-up period

This study investigates the performance of an anaerobic baffled reactor (ABR) during the start-up period of raw young landfill leachate treatment at two chemical oxygen demand (COD) to SO ratios of 20 and 4. The reactor was operated at ambient temperature and low organic loading rates (0.52, 0.76 and 1.05 kg COD/m3 per day). During the study, sulfate-reducing bacteria (SRB) activity increased at the lower ratio of COD/SO producing higher levels of sulfide and alkalinity. The dissolved sulfide concentration reached an inhibitory level above 250 mg/L, which caused a sharp reduction in the total COD removal efficiency from 77–80% to 32%. Total volatile fatty acid (TVFA) production proceeded at a constant level despite increased organic loading. As the effluent total and organic COD concentrations increased, the inhibitory effect of the inborn sulfide was correlated to the limitation experienced in the hydrolysis/acidogenesis stages, and thus VFA production and organic matter removal.

Cascade bioreactor with submerged biofilm for aerobic treatment of Tunisian landfill leachate

A bioreactor cascade with a submerged biofilm is proposed to treat young landfill leachate of jbel chakir landfill site south west from capital Tunis, Tunisia. The prototype was run under different organic loading charges varying from 0.6 to 16.3kgTOCm−3day−1. Without initial pH adjustment total organic carbon (TOC) removal rate varied between 65% and 97%. The total reduction of COD reached 92% at a hydraulic retention time of 36h. However, the removal of total kjeldahl nitrogen for loading charges of 0.5kgNm−3day−1 reached 75%. The adjustment of pH to 7.5 improved nitrogen removal to a rate of 85% for loading charge of 1kgNm−3day−1. The main bacterial groups responsible for a simultaneous removal of organic carbon and nitrogen belonged to Bacillus, Actinomyces, Pseudomonas and Burkholderia genera. These selected isolates showed a great capacity of degradation at different leachate concentrations of total organic carbon.

Pb(II) and Zn(II) adsorption onto Na- and Ca-montmorillonites in acetic acid/acetate medium: Experimental approach and geochemical modeling

Smectites are usually used as a clay barrier at the bottom of subsurface waste landfills due to their low permeability and their capacity to retain pollutants. The Na- and Ca-saturated SWy2 montmorillonites were interacted with initial Zn(NO3)2 or Pb(NO3)2 concentrations ranging from 10−6 to 10−2M with a solid/liquid ratio of 10gL−1 and using acetic acid/acetate as buffer at pH 5 in order to reproduce a biodegradable leachate of a young landfill. These experiments revealed that Zn and Pb sorption onto Na-SWy2 is higher than that onto Ca-SWy2 in the whole range of concentrations. Metal retention into both montmorillonites increases with the decrease in acetic acid/acetate concentration. The two-site protolysis model with no electrostatic term (2SPNE model) was used to model these experiments. As the experimental data of Zn sorption were well fitted, this model was validated and has been improved by taking into account the metal–acetate complexation in solution. In order to validate the model for Pb sorption, new selectivity coefficients have been determined, namely logKc(PbNa)=0.5 for Na-montmorillonite and logKc(PbCa)=0.3 for Ca-montmorillonite.

Removal of COD and colour from young municipal landfill leachate by Fenton process

Landfill is a common solution for the final disposal of municipal solid waste in Turkey. In recent years, studies of landfill leachate treatment by Fenton process have indicated that these methods can effectively reduce concentrations of organic contaminants and colour. The aim of this study is to investigate the removal efficiencies of colour and organic matter as COD from young municipal landfill leachate and the effect of operating conditions such as initial pH and Fenton’s reagent dosage. Leachate was collected from municipal sanitary landfill located in city of Konya, Turkey. The main characteristics of the leachate were: pH = 7.25, colour = 3510 ptCo, COD = 38200 mgL−1, BOD5 = 22000 mgL−1, ratio of BOD5/COD was 0.58 and alkalinity as CaCO3 = 10250 mgL−1. It is observed that presenting a high value of COD and BOD5 and the rate of BOD5/COD values indicate that the leachate can be defined as young. The treatment of the leachate by Fenton process was carried out in a batch reactor. Under the optimal operation conditions (initial pH = 3, 2000 mgL−1 Fe2+ and 5000 mgL−1 H2O2), 55.9% of the initial COD and 89.4% colour were removed.

Pilot-Scale Simulation of Landfill Bioreactor and Controlled Dumping of Fresh and Partially Stabilized Municipal Solid Waste in a Tropical Developing Country

Four pilot-scale lysimeters were used to study the benefits of landfill operation with and without leachate recirculation in tropical weather conditions. Young and old landfills were simulated by filling lysimeters with a segregated fraction of fresh municipal solid waste (MSW) and MSW mined from an open dump site, respectively, and periodically monitoring leachate quantity and quality and biogas quality. For each substrate, one lysimeter was operated as a bioreactor with leachate recirculation and another lysimeter was operated as a controlled dump, for a period of 10 months. Densities between 652 and 825 kg/m3 could be achieved with fresh and mined MSW. Despite such compaction during waste placement, bioreactor technology helps in leachate management, especially in the case of the young landfill lysimeter operated in tropical weather. The benefits of leachate recirculation in the young landfill lysimeter were evident from the significant decrease in chemical oxygen demand (COD) (86%), biochemical oxyge...

Coagulation-Flocculation and Air Stripping as a Pretreatment of Young Landfill Leachate~!2010-02-12~!2010-03-24~!2010-05-11~!

Coagulation-Flocculation and Air Stripping as a Pretreatment of Young Landfill Leachate~!2010-02-12~!2010-03-24~!2010-05-11~!

Migration of Organic Contaminants from Landfill: Minimum Thickness of Barriers

Point sources such as landfills, can release high concentrations of contaminants into the groundwater because of migration of leachate from its bottom, which is generated primarily as a result of precipitation falling on an active land- fill surface, leaching out the potential organic and inorganic contaminants from landfilled waste and discharging the same to groundwater in underlying aquifer. Leachate from young landfills has high dissolved solids content as well as a high concentration of organic matter. Landfill leachate has the potential to contaminate the surrounding environment and im- pair groundwater use. Organic contaminants in landfill leachate originate from incoming wastes or are produced as a re- sult of biochemical reactions taking place in landfills. To protect the groundwater from contamination by landfill leachate, it is quite essential to provide the bottom barrier of suitable thickness, and to minimize the amount of water that could en- ter the landfill to create leachate. The present study was undertaken to determine the rate of movement of potential con- taminants from its bottom to the aquifer media, so as to evolve a rational method for the determination of thickness of bot- tom barrier on sound engineering practice, in place of adopting a prescriptive standard, which is very common in most of the Asian countries. The study was undertaken for non conservative contaminant Dissolved Organic Carbon (DOC). The governing equation of contaminant transport was solved using finite difference method, and finite mass boundary condi- tion to ape the finite mass of contaminants in a landfill. The solution of the model was run in MatLab 7.0 for a range of Darcy velocities and retardation factors for a representative equivalent height of leachate. Design curves were drawn which can be used for determination of suitable barrier thickness on the basis of expected maximum concentration of DOC in landfill leachate and maximum permissible concentration of the same.