Effect of inoculum to substrate ratio (I/S) on municipal solid waste anaerobic degradation kinetics and potential

The goal of this study is to evaluate the impact of the inoculum to substrate ratio (I/S) on the anaerobic degradation potential of municipal solid waste (MSW). Reconstituted MSW samples were thus incubated under batch anaerobic conditions and inoculated with an increasing amount of inoculum originating from a mesophilic sludge digester. I/S tested values were 0 (no inoculum added), 0.015, 0.03, 0.06, 0.12, 0.25, 1, 2 and 4 (gVM_inoculum/gVM_waste). The results indicate that the apparent maximal rate of dissolved organic carbon accumulation is reached at I/S = 0.12. Under this level, the hydrolysis process is limited by the concentration of biomass and can thus be described as first order kinetics phenomena with respect to biomass for I/S ratios below 0.12. The maximum methane production rate and the minimal latency are reached at a ratio of 2. In addition to that, both methane signature and ARISA show a shift in the methanogenic populations from hydrogenotrophic to acetoclastic.     

Evaluation of a classification method for biodegradable solid wastes using anaerobic degradation parameters

We studied the biochemical and anaerobic degradation characteristics of 29 types of materials to evaluate the effects of a physical composition classification method for degradable solid waste on the computation of anaerobic degradation parameters, including the methane yield potential (L₀), anaerobic decay rate (k), and carbon sequestration factor (CSF). Biochemical methane potential tests were conducted to determine the anaerobic degradation parameters of each material. The results indicated that the anaerobic degradation parameters of nut waste were quite different from those of other food waste and nut waste was classified separately. Paper was subdivided into two categories according to its lignin content: degradable paper with lignin content of <0.05 g g VS^?1, and refractory paper with lignin content >0.15 g g VS^?1. The L₀, k, and CSF parameters of leaves, a type of garden waste, were similar to those of grass. This classification method for degradable solid waste may provide a theoretical basis that facilitates the more accurate calculation of anaerobic degradation parameters.     

BMP tests of source selected OFMSW to evaluate anaerobic codigestion with sewage sludge

The aim of this study is to characterize different types of source selected organic fraction of municipal solid waste (SS-OFMSW) in order to optimize the upgrade of a sewage sludge anaerobic digestion unit by codigestion. Various SS-OFMSW samples were collected from canteens, supermarkets, restaurants, households, fruit–vegetable markets and bakery shops. The substrates characterization was carried out getting traditional chemical–physical parameters, performing elemental analysis and measuring fundamental anaerobic digestion macromolecular compounds such as carbohydrates, proteins, lipids and volatile fatty acids. Biochemical methane potential (BMP) tests were conducted at mesophilic temperature both on single substrates and in codigestion regime with different substrates mixing ratios. The maximum methane yield was observed for restaurant (675 NmlCH₄/gVS) and canteens organic wastes (571 and 645 NmlCH₄/gVS). The best codigestion BMP test has highlighted an increase of 47% in methane production respect sewage sludge digestion.     

Ultrasound assisted biogas production from landfill leachate

The aim of this study is to increase biogas production and methane yield from landfill leachate in anaerobic batch reactors by using low frequency ultrasound as a pretreatment step. In the first part of the study, optimum conditions for solubilization of organic matter in leachate samples were investigated using various sonication durations at an ultrasound frequency of 20 kHz. The level of organic matter solubilization during ultrasonic pretreatment experiments was determined by calculating the ratio of soluble chemical oxygen demand (sCOD) to total chemical oxygen demand (tCOD). The sCOD/tCOD ratio was increased from 47% in raw leachate to 63% after 45 min sonication at 600 W/l. Non-parametric Friedman’s test indicated that ultrasonic pretreatment has a significant effect on sCOD parameter for leachate (p < 0.05). In the second part of the study, anaerobic batch reactors were operated for both ultrasonically pretreated and untreated landfill leachate samples in order to assess the effect of sonication on biogas and methane production rate. In anaerobic batch reactor feed with ultrasonically pretreated leachate, 40% more biogas was obtained compared to the control reactor. For statistical analysis, Mann–Whitney U test was performed to compare biogas and methane production rates for raw and pretreated leachate samples and it has been found that ultrasonic pretreatment significantly enhanced biogas and methane production rates from leachate (p < 0.05) in anaerobic batch reactors. The overall results showed that low frequency ultrasound pretreatment can be potentially used for wastewater management especially with integration of anaerobic processes.     

Determination of biogas generation potential as a renewable energy source from supermarket wastes

Fruit, vegetable, flower waste (FVFW), dairy products waste (DPW), meat waste (MW) and sugar waste (SW) obtained from a supermarket chain were anaerobically digested, in order to recover methane as a source of renewable energy. Batch mesophilic anaerobic reactors were run at total solids (TS) ratios of 5%, 8% and 10%. The highest methane yield of 0.44 L CH₄/g VS_added was obtained from anaerobic digestion of wastes (FVFW + DPW + MW + SW) at 10% TS, with 66.4% of methane (CH₄) composition in biogas. Anaerobic digestion of mixed wastes at 5% and 8% TS provided slightly lower methane yields of 0.41 and 0.40 L CH₄/g VS_added, respectively. When the wastes were digested alone without co-substrate addition, the highest methane yield of 0.40 L CH₄/g VS_added was obtained from FVFW at 5% TS. Generally, although the volatile solids (VS) conversion percentages seemed low during the experiments, higher methane yields could be obtained from anaerobic digestion of supermarket wastes. A suitable carbon/nitrogen (C/N) ratio, proper adjustment of the buffering capacity and the addition of essential trace nutrients (such as Ni) could improve VS conversion and biogas production yields significantly.     

Anaerobic digestion of microalgal biomass after ultrasound pretreatment

High rate algal ponds are an economic and sustainable alternative for wastewater treatment, where microalgae and bacteria grow in symbiosis removing organic matter and nutrients. Microalgal biomass produced in these systems can be valorised through anaerobic digestion. However, microalgae anaerobic biodegradability is limited by the complex cell wall structure and therefore a pretreatment step may be required to improve the methane yield. In this study, ultrasound pretreatment at a range of applied specific energy (16–67 MJ/kg TS) was investigated prior to microalgae anaerobic digestion. Experiments showed how organic matter solubilisation (16–100%), hydrolysis rate (25–56%) and methane yield (6–33%) were improved as the pretreatment intensity increased. Mathematical modelling revealed that ultrasonication had a higher effect on the methane yield than on the hydrolysis rate. A preliminary energy assessment indicated that the methane yield increase was not high enough as to compensate the electricity requirement of ultrasonication without biomass dewatering (8% VS).     

Impact of alkaline-hydrolyzed biosolids (Lystek) addition on the anaerobic digestibility of TWAS in lab – And full-scale anaerobic digesters

The effect of different Lystek biosolids doses on the anaerobic digestability of thickened waste activated sludge (TWAS) was evaluated in a lab- and full-scale anaerobic digester. The overall findings of this study emphasize the beneficial impact of Lystek addition to the lab- and full-scale anaerobic digesters in terms of enhanced biogas production and increased volatile suspended solids reduction (VSSR) efficiency. Lystek added at 4% by volume to TWAS increased the methane yield from 0.22 to 0.26 L CH₄/g VSS_added at an solids retention time (SRT) of 10 days, and from 0.27 to 0.29 L CH₄/g VSS_added at an SRT of 15 days. Furthermore, the VSSRs of 37% and 47% were observed for the TWAS, and the TWAS with 4% Lystek, while at an SRT of 15 days, the observed VSSR were 49% and 58%, respectively. The lab-scale study showed that the influence of Lystek addition on methane yield and solids destruction efficiencies was more pronounced at the shorter SRT, 20% enhancement (SRT of 10 d) vs. 9% enhancement (SRT of 15 d) for methane yield, and 27% (SRT of 10 d) vs. 22% (SRT of 15 d) for VSS destruction efficiency improvement. Furthermore, addition of 4% of Lystek to the feed of the full-scale anaerobic digester at St. Marys wastewater treatment plant (WWTP) resulted in a 50% increase in the average specific methanogenic activity and 23% increase in methane yield of the biochemical methane potential tests after eight months. The results showed that Lystek degradation kinetics were 40% faster than the TWAS, as reflected by first order kinetic coefficients of 0.053 d^?1 and 0.073 d^?1 for TWAS and Lystek at an SRT of 10 days.     

Need for improvements in physical pretreatment of source-separated household food waste

The aim of the present study was to investigate the efficiency in physical pretreatment processes of source-separated solid organic household waste. The investigation of seventeen Swedish full-scale pretreatment facilities, currently receiving separately collected food waste from household for subsequent anaerobic digestion, shows that problems with the quality of produced biomass and high maintenance costs are common. Four full-scale physical pretreatment plants, three using screwpress technology and one using dispergation technology, were compared in relation to resource efficiency, losses of nitrogen and potential methane production from biodegradable matter as well as the ratio of unwanted materials in produced biomass intended for wet anaerobic digestion. Refuse generated in the processes represent 13–39% of TS in incoming wet waste. The methane yield from these fractions corresponds to 14–36 Nm³/ton separately collected solid organic household waste. Also, 13–32% of N-tot in incoming food waste is found in refuse. Losses of both biodegradable material and nutrients were larger in the three facilities using screwpress technology compared to the facility using dispersion technology.¹ Thus, there are large potentials for increase of both the methane yield and nutrient recovery from separately collected solid organic household waste through increased efficiency in facilities for physical pretreatment. Improved pretreatment processes could thereby increase the overall environmental benefits from anaerobic digestion as a treatment alternative for solid organic household waste.     

Comparison of different liquid anaerobic digestion effluents as inocula and nitrogen sources for solid-state batch anaerobic digestion of corn stover

Effluents from three liquid anaerobic digesters, fed with municipal sewage sludge, food waste, or dairy waste, were evaluated as inocula and nitrogen sources for solid-state batch anaerobic digestion of corn stover in mesophilic reactors. Three feedstock-to-effluent (F/E) ratios (i.e., 2, 4, and 6) were tested for each effluent. At an F/E ratio of 2, the reactor inoculated by dairy waste effluent achieved the highest methane yield of 238.5 L/kgVS_feed, while at an F/E ratio of 4, the reactor inoculated by food waste effluent achieved the highest methane yield of 199.6 L/kgVS_feed. The microbial population and chemical composition of the three effluents were substantially different. Food waste effluent had the largest population of acetoclastic methanogens, while dairy waste effluent had the largest populations of cellulolytic and xylanolytic bacteria. Dairy waste also had the highest C/N ratio of 8.5 and the highest alkalinity of 19.3 g CaCO₃/kg. The performance of solid-state batch anaerobic digestion reactors was closely related to the microbial status in the liquid anaerobic digestion effluents.     

Evaluating the biogas potential of the dry fraction from pretreatment of food waste from households

At the waste handling company NSR, Helsingborg, Sweden, the food waste fraction of source separated municipal solid waste is pretreated to obtain a liquid fraction, which is used for biogas production, and a dry fraction, which is at present incinerated. This pretreatment and separation is performed to remove impurities, however also some of the organic material is removed. The possibility of realising the methane potential of the dry fraction through batch-wise dry anaerobic digestion was investigated. The anaerobic digestion technique used was a two-stage process consisting of a static leach bed reactor and a methane reactor. Treatment of the dry fraction alone and in a mixture with structural material was tested to investigate the effect on the porosity of the leach bed. A tracer experiment was carried out to investigate the liquid flow through the leach beds, and this method proved useful in demonstrating a more homogenous flow through the leach bed when structural material was added. Addition of structural material to the dry fraction was needed to achieve a functional digestion process. A methane yield of 98 m³/ton was obtained from the dry fraction mixed with structural material after 76 days of digestion. This was in the same range as obtained in the laboratory scale biochemical methane potential test, showing that it was possible to extract the organic content in the dry fraction in this type of dry digestion system for the production of methane.     

An experimental study on fermentative H2 production from food waste as affected by pH

Batch dark fermentation experiments were performed on food waste and mixtures of food waste and wastewater activated sludge to evaluate the influence of pH on biological H₂ production and compare the process performance with and without inoculum addition. The effect of a preliminary thermal shock treatment of the inoculum was also investigated as a means to harvest the hydrogenogenic biomass. The best performance in terms of both H₂ generation potential and process kinetics was observed at pH = 6.5 under all experimental conditions (no inoculum, and untreated or thermally treated inoculum added). H₂ production from food waste was found to be feasible even without inoculum addition, although thermal pre-treatment of the inoculum notably increased the maximum production and reduced the lag phase duration. The analysis of the fermentation products indicated that the biological hydrogen production could be mainly ascribed to a mixed acetate/butyrate-type fermentation. However, the presence of additional metabolites in the digestate, including propionate and ethanol, also indicated that other metabolic pathways were active during the process, reducing substrate conversion into hydrogen. The plateau in H₂ generation was found to mirror the condition at which soluble carbohydrates were depleted. Beyond this condition, homoacetogenesis probably started to play a role in the degradation process.     

Estimation of methane emission rate changes using age-defined waste in a landfill site

Long term methane emissions from landfill sites are often predicted by first-order decay (FOD) models, in which the default coefficients of the methane generation potential and the methane generation rate given by the Intergovernmental Panel on Climate Change (IPCC) are usually used. However, previous studies have demonstrated the large uncertainty in these coefficients because they are derived from a calibration procedure under ideal steady-state conditions, not actual landfill site conditions. In this study, the coefficients in the FOD model were estimated by a new approach to predict more precise long term methane generation by considering region-specific conditions. In the new approach, age-defined waste samples, which had been under the actual landfill site conditions, were collected in Hokkaido, Japan (in cold region), and the time series data on the age-defined waste sample’s methane generation potential was used to estimate the coefficients in the FOD model. The degradation coefficients were 0.050 1/y and 0.062 1/y for paper and food waste, and the methane generation potentials were 214.4 mL/g-wet waste and 126.7 mL/g-wet waste for paper and food waste, respectively. These coefficients were compared with the default coefficients given by the IPCC. Although the degradation coefficient for food waste was smaller than the default value, the other coefficients were within the range of the default coefficients. With these new coefficients to calculate methane generation, the long term methane emissions from the landfill site was estimated at 1.35 × 10⁴ m³-CH₄, which corresponds to approximately 2.53% of the total carbon dioxide emissions in the city (5.34 × 10⁵ t-CO₂/y).     

Anaerobic co-digestion of food waste and landfill leachate in single-phase batch reactors

In order to investigate the effect of raw leachate on anaerobic digestion of food waste, co-digestions of food waste with raw leachate were carried out. A series of single-phase batch mesophilic (35 ± 1 °C) anaerobic digestions were performed at a food waste concentration of 41.8 g VS/L. The results showed that inhibition of biogas production by volatile fatty acids (VFA) occurred without raw leachate addition. A certain amount of raw leachate in the reactors effectively relieved acidic inhibition caused by VFA accumulation, and the system maintained stable with methane yield of 369–466 mL/g VS. Total ammonia nitrogen introduced into the digestion systems with initial 2000–3000 mgNH₄–N/L not only replenished nitrogen for bacterial growth, but also formed a buffer system with VFA to maintain a delicate biochemical balance between the acidogenic and methanogenic microorganisms. UV spectroscopy and fluorescence excitation–emission matrix spectroscopy data showed that food waste was completely degraded.We concluded that using raw leachate for supplement water addition and pH modifier on anaerobic digestion of food waste was effective. An appropriate fraction of leachate could stimulate methanogenic activity and enhance biogas production.     

Spectroscopic characterization of organic matter of a soil and vinasse mixture during aerobic or anaerobic incubation

Mineralization potentials are often used to classify organic wastes. These methods involve measuring CO₂ production during batch experiments, so variations in chemical compounds are not addressed. Moreover, the physicochemical conditions are not monitored during the reactions. The present study was designed to address these deficiencies. Incubations of a mixture of soil and waste (vinasse at 20% dry matter from a fermentation industry) were conducted in aerobic and anaerobic conditions, and liquid samples obtained by centrifugation were collected at 2 h, 1 d and 28 d. Dissolved organic carbon (DOC) patterns highlighted that: there was a “soil effect” which increased organic matter (OM) degradation in all conditions compared to vinasse incubated alone; and OM degradation was faster under aerobic conditions since 500 mg kg^?1 of C remained after aerobic incubation, as compared to 4000 mg kg^?1 at the end of the anaerobic incubation period. No changes were detected by Fourier transform infrared spectroscopy (FTIR) between 2 h and 1 d incubation. At 28 days incubation, the FTIR signal of the aerobic samples was deeply modified, thus confirming the high OM degradation. Under anaerobic conditions, the main polysaccharide contributions (ν(C–O)) disappeared at 1000 and 1200 cm^?1, as also confirmed by the ¹³C NMR findings. Under aerobic incubation, a 50% decrease in the polysaccharide proportion was observed. Under anaerobic conditions, significant chemical modifications of the organic fraction were detected, namely formation of low molecular weight organic acids.     

Anaerobic co-digestion of the organic fraction of municipal solid waste with FOG waste from a sewage treatment plant: Recovering a wasted methane potential and enhancing the biogas yield

Anaerobic digestion is applied widely to treat the source collected organic fraction of municipal solid wastes (SC-OFMSW). Lipid-rich wastes are a valuable substrate for anaerobic digestion due to their high theoretical methane potential. Nevertheless, although fat, oil and grease waste from sewage treatment plants (STP-FOGW) are commonly disposed of in landfill, European legislation is aimed at encouraging more effective forms of treatment. Co-digestion of the above wastes may enhance valorisation of STP-FOGW and lead to a higher biogas yield throughout the anaerobic digestion process. In the present study, STP-FOGW was evaluated as a co-substrate in wet anaerobic digestion of SC-OFMSW under mesophilic conditions (37 °C). Batch experiments carried out at different co-digestion ratios showed an improvement in methane production related to STP-FOGW addition. A 1:7 (VS/VS) STP-FOGW:SC-OFMSW feed ratio was selected for use in performing further lab-scale studies in a 5 L continuous reactor. Biogas yield increased from 0.38 ± 0.02 L g VS_feed^?1 to 0.55 ± 0.05 L g VS_feed^?1 as a result of adding STP-FOGW to reactor feed. Both VS reduction values and biogas methane content were maintained and inhibition produced by long chain fatty acid (LCFA) accumulation was not observed. Recovery of a currently wasted methane potential from STP-FOGW was achieved in a co-digestion process with SC-OFMSW.     

Optimization of micro-aeration intensity in acidogenic reactor of a two-phase anaerobic digester treating food waste

Micro-aeration is known to promote the activities of hydrolytic exo-enzymes and used as a strategy to improve the hydrolysis of particulate substrate. The effect of different micro-aeration rates, 0, 129, 258, and 387 L-air/kg TS/d (denoted as LBR-AN, LBR-6h, LBR-3h and LBR-2h, respectively) on the solubilization of food waste was evaluated at 35 °C in four leach bed reactors (LBR) coupled with methanogenic upflow anaerobic sludge blanket (UASB) reactor. Results indicate that the intensity of micro-aeration influenced the hydrolysis and methane yield. Adequate micro-aeration intensity in LBR-3h and LBR-2h significantly enhanced the carbohydrate and protein hydrolysis by 21–27% and 38–64% respectively. Due to the accelerated acidogenesis, more than 3-fold of acetic acid and butyric acid were produced in LBR-3h as compared to the anaerobic treatment LBR-AN resulting in the maximum methane yield of 0.27 L CH₄/g VS_added in the UASB. The performance of LBR-6h with inadequate aeration was similar to that of LBR-AN with a comparable hydrolysis degree. Nevertheless, higher aeration intensity in LBR-2h was also unfavorable for methane yield due to significant biomass generation and CO₂ respiration of up to 18.5% and 32.8% of the total soluble hydrolysate, respectively. To conclude, appropriate micro-aeration rate can promote the hydrolysis of solid organic waste and methane yield without undesirable carbon loss and an aeration intensity of 258 L-air/kg TS/d is recommended for acidogenic LBR treating food waste.     

Batchwise mesophilic anaerobic co-digestion of secondary sludge from pulp and paper industry and municipal sewage sludge

Residues from forest-industry wastewater-treatment systems are treated as waste at many pulp and paper mills. These organic substances have previously been shown to have potential for production of large quantities of biogas. There is concern, however, that the process would require expensive equipment because of the slow degradation of these substances. Pure non-fibrous sludge from forest industry showed lower specific methane production during mesophilic digestion for 19 days, 53 ± 26 Nml/g of volatile solids as compared to municipal sewage sludge, 84 ± 24 Nml/g of volatile solids. This paper explores the possibility of using anaerobic co-digestion with municipal sewage sludge to enhance the potential of methane production from secondary sludge from a pulp and paper mill. It was seen in a batch anaerobic-digestion operation of 19 days that the specific methane production remained largely the same for municipal sewage sludge when up to 50% of the volatile solids were replaced with forest-industry secondary sludge. It was also shown that the solid residue from anaerobic digestion of the forest-industry sludge should be of suitable quality to use for improving soil quality on lands that are not used for food production.     

Anaerobic digestion and co-digestion of slaughterhouse waste (SHW): Influence of heat and pressure pre-treatment in biogas yield

Mesophilic anaerobic digestion (34 ± 1 °C) of pre-treated (for 20 min at 133 °C, >3 bar) slaughterhouse waste and its co-digestion with the organic fraction of municipal solid waste (OFMSW) have been assessed. Semi-continuously-fed digesters worked with a hydraulic retention time (HRT) of 36 d and organic loading rates (OLR) of 1.2 and 2.6 kg VS_feed/m³ d for digestion and co-digestion, respectively, with a previous acclimatization period in all cases. It was not possible to carry out an efficient treatment of hygienized waste, even less so when OFMSW was added as co-substrate. These digesters presented volatile fatty acids (VFA), long chain fatty acids (LCFA) and fats accumulation, leading to instability and inhibition of the degradation process. The aim of applying a heat and pressure pre-treatment to promote splitting of complex lipids and nitrogen-rich waste into simpler and more biodegradable constituents and to enhance biogas production was not successful. These results indicate that the temperature and the high pressure of the pre-treatment applied favoured the formation of compounds that are refractory to anaerobic digestion.The pre-treated slaughterhouse wastes and the final products of these systems were analyzed by FTIR and TGA. These tools verified the existence of complex nitrogen-containing polymers in the final effluents, confirming the formation of refractory compounds during pre-treatment.     

Release and fate of fluorocarbons in a shredder residue landfill cell: 2. Field investigations

The shredder residues from automobiles, home appliances and other metal containing products are often disposed in landfills, as recycling technologies for these materials are not common in many countries. Shredder waste contains rigid and soft foams from cushions and insulation panels blown with fluorocarbons. The objective of this study was to determine the gas composition, attenuation, and emission of fluorocarbons in a monofill shredder residue landfill cell by field investigation. Landfill gas generated within the shredder waste primarily consisted of CH₄ (27%) and N₂ (71%), without CO₂, indicating that the gas composition was governed by chemical reactions in combination with anaerobic microbial reactions. The gas generated also contained different fluorocarbons (up to 27 μg L^?1). The presence of HCFC-21 and HCFC-31 indicated that anaerobic degradation of CFC-11 occurred in the landfill cell, as neither of these compounds has been produced for industrial applications. This study demonstrates that a landfill cell containing shredder waste has a potential for attenuating CFC-11 released from polyurethane (PUR) insulation foam in the cell via aerobic and anaerobic biodegradation processes. In deeper, anaerobic zones of the cell, reductive dechlorination of CFCs to HCFCs was evident, while in the shallow, oxic zones, there was a high potential for biooxidation of both methane and lesser chlorinated fluorocarbons. These findings correlated well with both laboratory results (presented in a companion paper) and surface emission measurements that, with the exception from a few hot spots, indicated that surface emissions were negative or below detection.     

Methane emissions from MBT landfills

Within the scope of an investigation for the German Federal Environment Agency (“Umweltbundesamt”), the basics for the estimation of the methane emissions from the landfilling of mechanically and biologically treated waste (MBT) were developed. For this purpose, topical research including monitoring results regarding the gas balance at MBT landfills was evaluated.For waste treated to the required German standards, a methane formation potential of approximately 18–24 m³ CH₄/t of total dry solids may be expected. Monitoring results from MBT landfills show that a three-phase model with differentiated half-lives describes the degradation kinetics in the best way. This is due to the fact that during the first years of disposal, the anaerobic degradation processes still proceed relatively intensively. In addition in the long term (decades), a residual gas production at a low level is still to be expected.Most of the soils used in recultivation layer systems at German landfills show a relatively high methane oxidation capacity up to 5 l CH₄/(m² h). However, measurements at MBT disposal sites indicate that the majority of the landfill gas (in particular at non-covered areas), leaves the landfill body via preferred gas emission zones (hot spots) without significant methane oxidation. Therefore, rather low methane oxidation factors are recommended for open and temporarily covered MBT landfills. Higher methane oxidation rates can be achieved when the soil/recultivation layer is adequately designed and operated.Based on the elaborated default values, the First Order Decay (FOD) model of the IPCC Guidelines for National Greenhouse Gas Inventories, 2006, was used to estimate the methane emissions from MBT landfills. Due to the calculation made by the authors emissions in the range of 60,000–135,000 t CO_2-eq./a for all German MBT landfills can be expected. This wide range shows the uncertainties when the here used procedure and the limited available data are applied. It is therefore necessary to generate more data in the future in order to calculate more precise methane emission rates from MBT landfills. This is important for the overall calculation of the climate gas production in Germany which is required once a year by the German Government.