Feasibility study of a passive aeration reactor equipped with vertical pipes for compost stabilization of cow manure.

Pilot-scale composting was carried out with cow manure to evaluate the performances of two passive aeration systems: a conventional passive aeration system equipped with horizontal pipes and an unusual passive aeration method based on air delivery by means of vertical pipes. The effects of both types of passive aeration apparatus were investigated in order to determine the degree of composting rate by continuously monitoring temperature, moisture content, organic matter, electrical conductivity, pH and C/N ratio in the piles. Temperatures in the range of thermophily (55-65 degrees C) were reached in all runs within 1-2 days then lasting for about 1 week, a span long enough for pathogen abatement. Results suggest that passive aeration carried out by vertical pipes is more effective for air delivery into compost piles than conventional passive aeration of air adduction with horizontal pipes. The variation in the number of vertical pipes was revealed to be an important parameter for the control of composting rate and temperature. Composting rates estimated from the heat balance equation were substantially in agreement with those computed through the conversion ratio of total organic matter decrement. The conversion ratios and composting rates obtained in this study using passive aeration with vertical pipes were well aligned with those found using forced air delivery systems.     

Effects of the forced ventilation on composting of a solid olive-mill by-product ("alperujo") managed by mechanical turning

The evaluation of the most suitable aeration technology for olive-mill by-product "alperujo" (AL) composting was carried out by using two identical piles prepared by mixing AL with a bulking agent (fresh cow bedding) and a mature compost (as inoculant). Forced ventilation was employed in conjunction with mechanical turning in one of the piles, whereas only mechanical turning was used in the other pile. These two treatment methods were evaluated by assessing process efficiency and end-product quality. The results show that the composting process was completed in less time when forced ventilation was coupled with mechanical turning. A slight delay in the evolution of pH, C/N ratio, and biodegradation of fats and organic matter was observed when only turning was employed. However, the recommended method for composting AL was mechanical turning without forced ventilation since the composition of the end-product in this case was comparable to the composted AL using forced ventilation coupled with mechanical turning. Furthermore, there were substantial economic savings by selecting mechanical turning alone, which included capital costs for equipment.     

Application of a simplified mathematical model to estimate the effect of forced aeration on composting in a closed system

The aeration rate is a key process control parameter in the forced aeration composting process because it greatly affects different physico-chemical parameters such as temperature and moisture content, and indirectly influences the biological degradation rate. In this study, the effect of a constant airflow rate on vertical temperature distribution and organic waste degradation in the composting mass is analyzed using a previously developed mathematical model of the composting process. The model was applied to analyze the effect of two different ambient conditions, namely, hot and cold ambient condition, and four different airflow rates such as 1.5, 3.0, 4.5, and 6.0m(3)m(-2)h(-1), respectively, on the temperature distribution and organic waste degradation in a given waste mixture. The typical waste mixture had 59% moisture content and 96% volatile solids, however, the proportion could be varied as required. The results suggested that the model could be efficiently used to analyze composting under variable ambient and operating conditions. A lower airflow rate around 1.5-3.0m(3)m(-2)h(-1) was found to be suitable for cold ambient condition while a higher airflow rate around 4.5-6.0m(3)m(-2)h(-1) was preferable for hot ambient condition. The engineered way of application of this model is flexible which allows the changes in any input parameters within the realistic range. It can be widely used for conceptual process design, studies on the effect of ambient conditions, optimization studies in existing composting plants, and process control.     

Sanitary aspect of using partially treated landfill leachate as a water source in green waste composting

Shredded green wastes were composted in windrows, at the Harewood Whin landfill, near the city of York, in West Yorkshire, UK. Landfill leachate were added twice during the second and fourth week of the process in two piles. One pile was turned once every week for eight weeks and the other was turned twice, during the same period. Each time approximately, 2 m3 of leachate was added, into each pile. The two piles each contained about 45 m3 of shredded green waste. The effect of adding leachate on the sanitisation of the green waste during composting, was evaluated based on the changes in the levels of faecal coliforms and faecal streptococci. The results suggested that using leachate as the moisture source had no significant effect (tested with two factors ANOVA test) on the sanitisation process when compared with two similar piles, used as the control, for which tap water was used for moisture addition. In all four piles sanitisation was almost complete and below the acceptable levels. Additionally, the results indicated that there was no significant effect on the sanitisation process of the turning frequency.     

Assessment of internal condition of waste in a roofed landfill

Recently, roofed landfills have been gaining popularity in Japan. Roofed landfills have several advantages over non-roofed landfills such as eliminating the visibility of waste and reducing the spread of offensive odours. This study examined the moisture balance and aeration conditions, which promote waste stabilisation, in a roofed landfill that included organic waste such as food waste. Moisture balance was estimated using waste characterization and the total amount of landfilled waste. Internal conditions were estimated based on the composition, flux, and temperature of the landfill gas. Finally, in situ aeration was performed to determine the integrity of the semi-aerobic structure of the landfill.With the effects of rainfall excluded, only 15% of the moisture held by the waste was discharged as leachate. The majority of the moisture remained in the waste layer, but was less than the optimal moisture level for biodegradation, indicating that an appropriate water spray should be administered. To assess waste degradation in this semi-aerobic landfill, the concentration and flow rate of landfill gas were measured and an in situ aeration test was performed. The results revealed that aerobic biodegradation had not occurred because of the unsatisfactory design and operation of the landfill.     

Numerical simulation of landfill aeration using computational fluid dynamics

The present study is an application of Computational Fluid Dynamics (CFD) to the numerical simulation of landfill aeration systems. Specifically, the CFD algorithms provided by the commercial solver ANSYS Fluent 14.0, combined with an in-house source code developed to modify the main solver, were used. The unsaturated multiphase flow of air and liquid phases and the biochemical processes for aerobic biodegradation of the organic fraction of municipal solid waste were simulated taking into consideration their temporal and spatial evolution, as well as complex effects, such as oxygen mass transfer across phases, unsaturated flow effects (capillary suction and unsaturated hydraulic conductivity), temperature variations due to biochemical processes and environmental correction factors for the applied kinetics (Monod and 1st order kinetics). The developed model results were compared with literature experimental data. Also, pilot scale simulations and sensitivity analysis were implemented. Moreover, simulation results of a hypothetical single aeration well were shown, while its zone of influence was estimated using both the pressure and oxygen distribution. Finally, a case study was simulated for a hypothetical landfill aeration system. Both a static (steadily positive or negative relative pressure with time) and a hybrid (following a square wave pattern of positive and negative values of relative pressure with time) scenarios for the aeration wells were examined. The results showed that the present model is capable of simulating landfill aeration and the obtained results were in good agreement with corresponding previous experimental and numerical investigations.     

Influence of aeration rate and biodegradability fractionation on composting kinetics

The influences of aeration rate and biodegradability fractionation on biodegradation kinetics during composting were studied. The first step was the design of a suitable lab-reactor that enabled the simulation of composting. The second step comprised of composting trials of six blends of sludge (originating from a food processing effluent) with wood chips using aeration rates of 1.69, 3.62, 3.25, 8.48, 11.98 and 16.63 L/h/kg DM of mixture. Biodegradation was evaluated by respiration measurements and from the analysis of the substrate (dry matter, organic matter, total carbon and chemical oxygen demand removal). Continuous measurement of oxygen consumption was coupled with the analysis of initial substrate and composted product for chemical oxygen demand (in the soluble and non-soluble fractions), which enabled an evaluation of the organic matter biodegradability. Oxygen requirements to remove both the easily and slowly biodegradable fractions were determined. Dividing the substrate into different parts according to biodegradability allowed explanation of the influence of aeration rate on stabilization kinetics. Considering that the biodegradation kinetics were of the first-order, the kinetic constants of the easily and slowly biodegradable fractions were calculated as a function of temperature. The methodology presented here allows the comparison of organic wastes in terms of their content of easily and slowly biodegradable fractions and the respective biodegradation kinetics.     

Leachate recirculation: moisture content assessment by means of a geophysical technique

Bioreactor technology is a waste treatment concept consisting in speeding up the biodegradation of landfilled waste by optimizing its moisture content through leachate recirculation. The measurement of variations in waste moisture content is critical in the design and control of bioreactors. Conventional methods such as direct physical sampling of waste reach their limits due to the interference with the waste matrix. This paper reviews geophysical measurements such as electrical direct current and electromagnetic slingram methods for measuring the electrical conductivity. Electrical conductivity is a property, which is linked to both moisture and temperature and can provide useful indications on the biodegradation environment in the waste mass. The study reviews three site experiments: a first experimentation shows the advantages (correlation between conductive anomaly and water seepage) but also the limits of geophysical interpretation; the two other sites allow the leachate recirculation to be tracked by studying the relative resistivity variation versus time from electrical 2D imaging. Even if some improvements are necessary to consider geophysical measurements as a real bioreactor monitoring tool, results are promising and could lead to the use of electrical 2D imaging in bioreactor designing.     

Modelling of moisture-dependent aerobic degradation of solid waste

In landfill, high temperature levels come from aerobic reactions inside the waste surface layer. They are known to make anaerobic processes more reliable, by partial removal of easily biodegradable substrates. Aerobic biodegradation of the main components of biodegradable matter (paper and cardboard waste, food and yard waste) is considered. In this paper, two models which take into account the effect of moisture on aerobic biodegradation kinetics are discussed. The first one (Model A) is a simple, first order, substrate-related model, which assumes that substrate hydrolysis is the limiting step of the process. The second one (Model B) is a biomass-dependant model, considering biological growth processes. Respirometric experiments were performed in order to evaluate the efficiency of each model. The biological oxygen demands of shredded paper and cardboard samples and of food and yard waste samples prepared at various initial water contents were measured. These experimental data were used to identify model parameters. Model A, which includes moisture dependency on the maximum amount of biodegraded matter, is relevant for paper and cardboard biodegradation. On the other hand, Model B, including moisture effect on the growth rate of biomass is suitable to describe food and yard waste biodegradation.     

Biodegradation of Coproducts from Industrially Processed Corn in a Compost Environment

Information pertaining to biodegradability of renewable polymeric material is critical for the design and development of single-use biodegradable consumer products. The rate and extent of biodegradation of corn fiber, corn zein, cornstarch, distillers grain, and corn gluten meal were evaluated in compost environments under variable temperature, pH, and moisture conditions. Generally, composts with higher temperature (40°C), neutral pH (7.0), and 50%–60% moisture appeared to be ideal for corn coproduct biodegradation, particularly for corn gluten meal and corn zein. Low moisture conditions slowed biodegradation considerably, but degradation rates improved when moisture content increased up to 60%. Thereafter, increased moisture particularly slowed the degradation of corn gluten meal and corn zein, whereas cornstarch degradation remained unaffected. At low pH (4.0) and high pH (11.0) the rate of degradation of most coproducts was slowed somewhat. Cornstarch degradation was slower at pH 7.0, but degradation improved with increased temperatures. Increase in compost temperature from 25 to 40°C (in 5°C increments) also improved biodegradation of corn fiber and distillers grain. Addition of 1% urea to compost as a nitrogen source decreased the extent of biodegradation nearly 40% for corn gluten meal and corn zein, and 20% for cornstarch samples. Treatment of compost with 0.02% azide inhibited biodegradation of all coproducts, suggesting that the presence of metabolically active microbial cells is required for effective degradation of biobased materials in a compost environment.     

Methane and carbon dioxide emission in a two-phase olive oil mill sludge windrow pile during composting

The aim of this work was to make some preliminary evaluations on CO(2) and CH(4) emissions during composting of two-phase olive oil mill sludge (OOMS). OOMS, olive tree leaves (OTL) and shredded olive tree branches (OTB) were used as feedstock for Pile I and Pile II with a 1:1:1 and 1:1:2v/v ratio, respectively. Each pile was originally 1.2m high, 2.0m wide and approximately 15.0m long. Four 500 ml volume glass funnels were inverted and introduced in each pile, two in the core (buried 50-60 cm from the surface) and two near the surface under a thin 10-15 cm layer of the mixture. Thin (0.5 cm diameter) plastic, 80 cm long tubes were connected to the funnels. A mobile gas analyser (GA2000) was used to measure the composition (by volume) of O2, CO2 and CH4 on a daily basis. The funnels were removed prior to each turning and reinserted afterwards. From each pair of funnels (core and surface) of both piles, one was kept closed between samplings. Two way ANOVA was used to test differences between piles and among the tubes. Post hoc Tukey tests were also used to further investigate these differences. There was a significant difference (at p<0.001) in the two piles for all three gases. The average concentrations of O2, CO2 and CH4 in Pile I, from all four funnels was 16.86%, 3.89% and 0.25%, respectively, where for Pile II the average values were 18.07%, 2.38% and 0.04%, respectively. The presence of OOMS in larger amounts in Pile I (resulting in more intense decomposing phenomena), and the larger particle size of OTB in Pile II (resulting in increasing porosity) are the probable causes of these significant differences. Samples from open funnels presented lower, but not significantly lower, O2 composition (higher for CO2 and CH4) in comparison with closed funnels in both depths and both piles. Not significant were also the different mean gas compositions between core and surface funnels in the same pile.     

Laboratory determination of compost physical parameters for modeling of airflow characteristics

Physical parameters of 12 co-compost cover materials were experimentally determined and predicted variations in airflow characteristics were evaluated under varying moisture contents. Predicted air-filled porosity showed high correlation with measured air-filled porosity, facilitating development of a reliable model of air-filled porosity that makes it possible to predict the effect of varying moisture content and compost bed height on air-filled porosity and permeability. Predicted air-filled porosity decreased with increasing moisture content and compost depth for all materials. Air-filled porosity of corn stalks, oat straw, soybean straw, leaves, alfalfa hay, wheat straw, silage, wood shavings and sawdust was in the range of 38-99%. Turkey litter, soil compost blend and beef manure showed air-filled porosity values less than 30% near saturation and the bottom of pile. In concert with the findings of other researchers, effective particle size of all materials increased with increasing moisture content from 20% to 80% of water holding capacity (WHC). It increased dramatically near saturation. In general, permeability increased with increasing air-filled porosity and decreasing bulk density, but the relationship between permeability and moisture content is complex. Permeability is dependent on the balance between particle size and air-filled porosity. If the influence of aggregated particle size on the permeability is significant, it will compensate for the effect of reduced air-filled porosity caused by compaction and moisture content. In this case, permeability will increase; in the reverse case, it will decrease. Permeability decreased for corn stalks, oat straw, silage, wood shavings, soybean straw, sawdust, turkey litter and wheat straw with increasing moisture content from 20% WHC to 50% WHC, regardless of the depth of the compost bed. But the permeability increased with increasing moisture level from 50% to 80% WHC at moderate to shallow simulated bed depths. The soil compost blend and leaves showed the permeability increasing when the moisture increased not only from 50% to 80% WHC but also from 20% to 50% WHC. Permeability of alfalfa hay and beef manure always decreased with increasing moisture levels and pile depth. In this study the maximum wet bulk density and mechanical strength decreased with increasing the moisture content. The method described for determining physical properties under varying moisture contents and compost bed depths will be very useful for designing and modeling airflow characteristics of a mortality composting process with a variety of materials.     

Study on the quality and stability of compost through a Demo Compost Plant

This study is concerned with the performance of a Demo Compost Plant for the development of acceptable composting technology in Bangladesh. The Demo Compost Plant was setup at the adjacent area of an existing compost plant located at Khulna city in Bangladesh. Four different composting technologies were considered, where Municipal Solid Waste (MSW) were used as a raw material for composting, collected from the adjacent areas of the plant. Initially the whole composting system was conducted through two experimental setups. In the 1st setup three different types of aerators (horizontal and vertical passively aerator and forced aerator) were selected. For a necessary observation four piles, using only MSW as the input materials in the first three compost pile, the fourth one was the existing Samadhan’s compost pile. Based on the analysis of the experimental findings, the horizontal passively aerated composting technique is suitable for Bangladesh as it had better performance for reducing composting period than that of the others. It was being observed from the quality parameters of compost in the both 1st and 2nd setup that as the waste directly come from kitchen, degradation rate of waste shows a positive result for reducing this waste and there is no possibility of toxic contamination, when it would be used as a soil conditioner. Though there is no significant improvement in the quality of the final product in the 2nd setup as comparing with the 1st setup but it fulfills one of the main objectives of this study is to reduce the whole composting period as well as immediate management of the increasing amount of waste and reducing load on landfill. Selfheating tests reveal that degree of stability of compost with respect to maturation period was remained in the acceptable level, which was further accelerated due to the use of organic additives.     

Characteristics of municipal solid waste and sewage sludge co-composting

The purpose of this work is to study the characteristics of the co-composting of municipal solid waste (MSW) and sewage sludge (SS). Four main influencing factors (aeration pattern, proportion of MSW and SS, aeration rate and mature compost (MC) recycling) were systematically investigated through changes of temperature, oxygen consumption rate, organic matters, moisture content, carbon, nitrogen, carbon-to-nitrogen ratio, nitrogen loss, sulphur and hydrogen. We found that a continuous aeration pattern during composting was superior to an intermittent aeration pattern, since the latter delayed the composting process. A 3:1 (v:v) mixture of MSW and SS was most beneficial to composting. It maintained the highest temperature for the longest duration and achieved the fastest organic matter degradation and highest N content in the final composting product. A 0.5L/minkgVS aeration rate best ensured rapid initiation and maintained moderate moisture content for microorganisms. After the mature MC was recycled to the fresh materials as a bulking agent, the structure and moisture of the initial materials were improved. A higher proportion of MC resulted in quicker decrease of the temperature, oxygen consumption rate and moisture. Therefore a 3:1:1 (v:v:v) proportion of MSW: SS: MC is recommended.     

Co-composting of livestock manure with rice straw: Characterization and establishment of maturity evaluation system

Composting is considered to be a primary treatment method for livestock manure and rice straw, and high degree of maturity is a prerequisite for safe land application of the composting products. In this study pilot-scale experiments were carried out to characterize the co-composting process of livestock manure with rice straw, as well as to establish a maturity evaluation index system for the composts obtained. Two pilot composting piles with different feedstocks were conducted for 3 months: (1) swine manure and rice straw (SM–RS); and (2) dairy manure and rice straw (DM–RS). During the composting process, parameters including temperature, moisture, pH, total organic carbon (TOC), organic matter (OM), different forms of nitrogen (total, ammonia and nitrate), and humification index (humic acid and fulvic acid) were monitored in addition to germination index (GI), plant growth index (PGI) and Solvita maturity index. OM loss followed the first-order kinetic model in both piles, and a slightly faster OM mineralization was achieved in the SM–RS pile. Also, the SM–RS pile exhibited slightly better performance than the DM–RS according to the evolutions of temperature, OM degradation, GI and PGI. The C/N ratio, GI and PGI could be included in the maturity evaluation index system in which GI > 120% and PGI > 1.00 signal mature co-composts.     

Simple technologies for on-farm composting of cattle slurry solid fraction

Composting technologies and control systems have reached an advanced stage of development, but these are too complex and expensive for most agricultural practitioners for treating livestock slurries. The development of simple, but robust and cost-effective techniques for composting animal slurries is therefore required to realise the potential benefits of waste sanitation and soil improvement associated with composted livestock manures. Cattle slurry solid fraction (SF) was collected at the rates of 4m(3)h(-1) and 1m(3)h(-1) and composted in tall (1.7 m) and short (1.2m) static piles, to evaluate the physicochemical characteristics and nutrient dynamics of SF during composting without addition of bulking agent materials, and without turning or water addition. Highest maximum temperatures (62-64 °C) were measured in tall piles compared to short piles (52 °C). However, maximum rates of organic matter (OM) destruction were observed at mesophilic temperature ranges in short piles, compared to tall piles, whereas thermophilic temperatures in tall piles maximised sanitation and enhanced moisture reduction. Final OM losses were within the range of 520-660 g kg(-1) dry solids and the net loss of OM significantly (P<0.001) increased nutrient concentrations during the composting period. An advanced degree of stabilization of the SF was indicated by low final pile temperatures and C/N ratio, low concentrations of NH(4)(+) and increased concentrations of NO(3)(-) in SF composts. The results indicated that minimum intervention composting of SF in static piles over 168 days can produce agronomically effective organic soil amendments containing significant amounts of OM (772-856 g kg(-1)) and plant nutrients. The implications of a minimal intervention management approach to composting SF on compost pathogen reduction are discussed and possible measures to improve sanitation are suggested.     

Influence of aeration on CH4, N2O and NH3 emissions during aerobic composting of a chicken manure and high C/N waste mixture

Co-composting of chicken manure, straw and dry grasses was investigated in a forced aeration system to estimate the effect of aeration rates on NH₃, CH₄ and N₂O emissions and compost quality. Continuous measurements of gas emissions were carried out and detailed gas emission patterns were obtained using an intermittent-aeration of 30 min on/30 min off at rates of 0.01 (A1), 0.1 (A2) and 0.2 (A3) m³ min⁻¹ m⁻³. Concentrations of CH₄ and N₂O at the low aeration rate (A1) were significantly greater than those at the other two rates, but there was no significant difference between the A2 and A3 treatments. CH₄ and N₂O emissions for this mixture could be controlled when the composting process was aerobic and ammonia emissions were reduced at a lower aeration rate. Comparison of CH₄, N₂O, NH₃ emissions and compost quality showed that the aeration rate of the A2 treatment was superior to the other two aeration rates.     

Influence of aeration rate on nitrogen dynamics during composting

The paper aimed to study the influence of aeration rate on nitrogen dynamics during composting of wastewater sludge with wood chips. Wastewater sludge was sampled at a pig slaughterhouse 24h before each composting experiment, and mixtures were made at the same mass ratio. Six composting experiments were performed in a lab reactor (300 L) under forced aeration. Aeration flow was constant throughout the experiment and aeration rates applied ranged between 1.69 and 16.63 L/h/kg DM of mixture. Material temperature and oxygen consumption were monitored continuously. Nitrogen losses in leachates as organic and total ammoniacal nitrogen, nitrite and nitrate, and losses in exhaust gases as ammonia were measured daily. Concentrations of total carbon and nitrogen i.e., organic nitrogen, total ammoniacal nitrogen, and nitrite and nitrate were measured in the initial substrates and in the composted materials. The results showed that organic nitrogen, which was released as NH4+/NH3 by ammonification, was closely correlated to the ratio of carbon removed from the material to TC/N(org) of the initial substrates. The increase of aeration was responsible for the increase in ammonia emissions and for the decrease in nitrogen losses through leaching. At high aeration rates, losses of nitrogen in leachates and as ammonia in exhaust gases accounted for 90-99% of the nitrogen removed from the material. At low aeration rates, those accounted for 47-85% of the nitrogen removed from the material. The highest concentrations of total ammoniacal nitrogen in composts occurred at the lowest aeration rate. Due to the correlation of ammonification with biodegradation and to the measurements of losses in leachates and in exhaust gases, the pool NH4+/NH3 in the composting material was calculated as a function of time. The nitrification rate was found to be proportional to the mean content of NH4+/NH3 in the material, i.e., initial NH4+/NH3 plus NH4+/NH3 released by ammonification minus losses in leachates and in exhaust gases. The aeration rate was shown to be a main parameter affecting nitrogen dynamics during composting since it controlled the ammonification, the ammonia emission and the nitrification processes.     

Influence of compost covers on the efficiency of biowaste composting process

The temperature of matured compost is an indicator of feedstock quality and also a good feedback informing about the suitability of an applied technological procedure. Two independent experiments using the technology of windrow composting at open area were conducted with the final goal to evaluate the effect of compost pile covering (in comparison with uncovered piles) on the course of composting process – behaviour of temperature over time and oxygen content. Two types of sheets were used – Top Tex permeable sheet and impermeable polyethylene sheet. The experiment I (summer months) aimed at comparison of efficiency between the Top Tex sheet cover and the uncovered compost piles, while experiment II (autumn months) compared treatments using the Top Tex sheet and polyethylene sheet by contrast. Within the experiment I the composts consisted of cattle slurry and fresh grass matter at a ratio of 1:1, in case of experiment II consisted of pig/cattle manure, fresh grass matter and chipped material at a ratio of about 1:2:1. The obtained data showed no significant differences among the cover treatments according to ANOVA. The only exception was oxygen content in pile 4 (experiment II) under Top Tex sheet, where a markedly higher oxygen content than under polyethylene sheet was measured during the whole composting period. It was the only case where statistical analysis proved a significant difference; the p-value was 0.0002.     

An investigation of the presence of methane and other gases at the Uzundere-Izmir solid waste disposal site, Izmir, Turkey

Izmir is a large metropolitan city with a population of 3,114,860. The city consists of 27 townships, each township has a population of not less than 10,000 inhabitants. The two major solid waste disposal sites are in the townships of Uzundere and Harmandali. The amount of solid waste that is disposed at each of these sites is about 800 and 1800 t/day, respectively. In Uzundere, compost is produced from the organic fraction of urban solid wastes while the residual material is deposited at a disposal site with a remaining capacity of 700,000 m(3) as of 2001. Gas monitoring and measurements were carried out at the disposal site in Uzundere. For this purpose, nine sampling wells were drilled on selected locations. Each well was furnished with perforated metal pipes suitable for gas monitoring and measurements. The following gases were monitored: O(2), CH(4), CO, CO(2), and H(2)S. The most important finding was that the concentrations of CH(4) in the wells ranged from 7 to 57%. Dilution of the CH(4) by O(2) down to the LEL levels (5-15%) is always possible and poses a continuing risk at the site. Furthermore, the levels of O(2) require that access to the site be limited to only authorized personnel.