GAS EMISSIONS OF YAKACIK CLOSED SOLID WASTE LANDFILL SITE IN ISTANBUL

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1 Volume 13 No REPRINT pp GAS EMISSIONS OF YAKACIK CLOSED SOLID WASTE LANDFILL SITE IN ISTANBUL Goksel Demir - H. Kurtulus Ozcan - Semih Nemlioglu Naim Sezgin - Mehmet Borat - Cuma Bayat Angerstr Freising - Germany Phone: ++49 (0) Fax: (0) parlar@psp-parlar.de

2 GAS EMISSIONS OF YAKACIK CLOSED SOLID WASTE LANDFILL SITE IN ISTANBUL Goksel Demir, H. Kurtulus Ozcan, Semih Nemlioglu, Naim Sezgin, Mehmet Borat and Cuma Bayat Istanbul University, Faculty of Engineering, Department of Environmental Engineering, Avcilar - Istanbul, Turkey Presented at the 12 th International Symposium on Environmental Pollution and its Impact on Life in the Mediterranean Region (MESAEP & SECOTOX), Antalya, Turkey, Oct SUMMARY Landfill gases are formed as a result of decomposition of the organic components of the solid waste. Because of the adverse effects on both the public health and the environment, the control of landfill gas emissions requires an effective gas control system. The methods commonly applied in controlling landfill gases are combustion and/or electrical energy production. In this study, the gases in Istanbul Yakacik unsanitary landfill have been examined. Yakacik is surrounded by inhabited buildings. Since 1979, the municipal and industrial wastes of Kartal and Pendik provinces have been dumped in Yakacik landfill, which covers an area of m 2 and stores m 3 of waste. There is a landfill gas combustion plant on this rehabilitated and closed Yakacik landfill. In this study, the major landfill gases, methane (CH 4 ), oxygen (O 2 ), carbon dioxide (CO 2 ), have been investigated together with their gas flow rate and atmospheric temperatures in the year The monthly average of methane concentration obtained from Yakacik solid waste combustion plant in 2001 varies between 40 % and 67.7 % in volume and its annual average is about 51 % in volume. The total gas flow rate at the combustion plant varies between and m 3 with an annual average of m 3. The total amount of methane gas produced daily varies between 55.5 and m 3 with an annual average of 87.5 m 3 depending on the gas production. Landfill gases depict an explosive behavior, when their concentration in air is between 5 % - 15 % in volume. Because of the fact that some excessive methane concentrations were measured in this combustion plant, effective combustion should continue in such cases for the sake of public health and the protection of the environment. KEYWORDS: Gas emission, landfill, air pollution, solid waste, Istanbul, Turkey. INTRODUCTION The properties and amount of solid wastes vary not only with respect to the country, but also with respect to the regions and even to the neighborhoods of a city. This variation is highly dependent on the socio-economic structure and human consumption habits. In Turkey, human waste production is 0.61 kg/person-day. This value varies considerably in Turkey; in rural areas it approaches zero, while in urbanized areas it rises to 2-3 kg/person-day. The average value in Istanbul is 0.65 kg/person-day [1, 2]. Solid waste landfills are quite different due to their heterogeneous structures and many decomposable matters [3]. The chemical and physical processes in a landfill contribute to the decomposition of solid wastes, but the most important process is the biological decomposition, that results in landfill gas production. In the initial stages of the biological decomposition process is aerobic due to the existence of oxygen. This results in the formation of water and carbon dioxide. This continues until the oxygen in that environment is exhausted. When there is no oxygen left in the environment, anaerobic conditions arise and the organic components decompose after a chain of reactions [4]. Some factors that greatly affect the biological decomposition of solid wastes are the nutrient ingredients of the waste, temperature, moisture, ph, particle dimensions, density and the composition of the buried wastes [3, 5]. Landfill gases are composed of a variety of gases, methane (45 % - 60 %) and carbon dioxide (40 % - 60 %) account for a greater portion, while the remaining portion is composed of nitrogen, sulphide, disulphide, ammonium, hydrogen, carbon monoxide and trace components [6]. The amount of methane in the troposphere increases by 1 % annually. This increase in methane concentrations necessitates the characterization studies be performed. It has been found that 18 % of the total global warming is caused by methane gas. This value corresponds to 500 million tons, million tons of which are produced by solid waste 974

3 Parameter TABLE 1 - The annual variation of the contents of solid wastes in Istanbul [9]. Basturk (1979) WHO-UNDP (1981) CH 2 M Hill (1992) Arıkan (1996) Ash Organic matter Paper Plastic Glass Textile Metal Other matters Diaper landfills. Of the landfill gases, methane depicts explosive properties if its concentration in air is between 5 15 %. If the amount of methane reaches these values but the amount of oxygen is limited, the risk of explosion is highly decreased [7]. According to the year 2000 census, Istanbul is the most crowded city in Turkey with a population of The average daily solid waste dumped in Istanbul is 9000 tons over 45 % of which consists of organic matters [8]. This high percentage results in big amounts of landfills in Istanbul. Resulting landfill gases depict explosive properties and, therefore, they need to be either removed safely from the covered solid waste landfill areas or be utilized [9]. The annual variation of the contents of solid wastes is given in Table 1. areas. In 1995 this area was covered by soil and rehabilitated, the landfill gases were removed by wells. These gases have been burned in the combustion unit since This closed solid waste landfill emits a significant amount of gas, that contributes to air pollution [9, 11]. Fig. 1 shows the location of Yakacik closed solid waste landfill in Istanbul. In Istanbul, the water content of solid waste is given to be %, the organic matter content %, C/N ratio 30 35, and calorific value kj/kg [1]. There are a limited number of research studies about the solid waste landfill gases in Istanbul. These studies show that the amount of formation of solid waste landfill gases vary considerably, and among the organic gases, methane is mostly in the combustible range [9, 10]. Also we must state that the oxygen amount in the wells is not less than the oxygen amount in the atmosphere, which may be a sign of malfunction of the vents. Therefore, it has to be analyzed regarding gas accumulation and explosion. In this study, measurements of methane (CH 4 ) (major gas in solid waste landfills), oxygen (O 2 ), carbon dioxide (CO 2 ), temperature and emission in year 2001 have been performed in Yakacik in Istanbul, which is surrounded by buildings and which has a combustion unit on the landfill. In Yakacik unsanitary solid waste dumping area, m 3 of waste has been dumped on an m 2 area. Since 1979 household and industrial wastes of Pendik and Kartal, which are provinces of Istanbul, have been dumped in this landfill. In 1990 this landfill was closed to waste dumping, because it had become surrounded by urban FIGURE 1 Location of Yakacik closed dumping site in Istanbul. MATERIALS AND METHODS The aim of this study is to determine the important gas emissions of the closed solid waste landfill located in Yakacik on the Anatolian side of Istanbul. Therefore the concentrations of CH 4, CO 2, O 2 gases in the combustion room have been measured in volume percentage and the total gas entering the chamber have been measured in m

4 CH4 (Vol. %) Time (month) CO 2 ( vol.%) Time (month) Oxygen (Vol.%) 3 2,5 2 1,5 1 0,5 0 Time (month) FIGURE 2 Monthly methane, carbon dioxide and oxygen concentration distribution in

5 The gases that accumulate in the 11 vents that are closed to the atmosphere in the landfill are connected to a manifold by pipes. The accumulated gases in the manifold are transferred to the combustion unit in a controlled manner. Among the 11 vents, 2-3 are selected according to the methane content, and combustion is performed. Combustion unit is composed of gas analytical system, combustion chamber and vents. The CH 4, CO 2, O 2 concentrations have been measured by using the Winter Gas - Warnanlagen DGM 9 model analysis system. The analysis was performed in 2001, each month on the 10 th and 20 th day and 7 times a day between 8:00 16:00 hrs. during the weekdays, on which the combustion units were active. The arithmetic averages of the measurement values have been calculated and the monthly emission data are found. Also the temperature values have been determined in the external environment [12]. RESULTS Fig. 2 shows the monthly CH 4, CO 2 and O 2 concentrations that were measured in the Istanbul Yakacik solid waste landfill gas combustion plant during the year As seen in Fig. 2, methane concentrations vary between 40.1 % and 67.7 % in volume, and the annual volume average is about 51 %. The highest concentration values are reached during winter in the months of January, February and December of the year 2001, with the highest in December 2001, which is 67.7 % in volume. During the April September 2001 interval methane concentration is quite less with the least value in May 2001 and 40.1 % in volume. The monthly average CO 2 concentration varies between 22.6 and 26.9 % in the year 2001 with an average of 24.7 % in volume. CO 2 concentration depicts a variable distribution with small amount of variations in the year 2001, low CO 2 concentration has been measured in May, June, and July period, but the highest volume of 26.9 % was reached in August, whereas the lowest volume of 22.6 % was reached in December. The average monthly O 2 concentration varies between 0.1 % and 2.5 % in volume, with an annual average of 0.8 % volume. The O 2 concentration in January July interval is stable and quite close to 0.5 %, but the highest value of 2.5 % was reached in September after the lowest value of 0.1 % in August. The total gas amounts of CH 4, CO 2 and O 2 that arrive at the combustion plant daily are given in Fig. 3. The total gas amount varies between and m 3 with an annual average of m 3. Higher values are reached in the first 7 months of the year, while the lower ones are reached in the rest of the year. The total amount of methane gas formation is dependent on the total amount of gas formed and varies in the m 3 range with an annual average of 87.5 m 3. The average amount of CO 2 that arrives at the combustion unit depends on the total gas formation and varies between 29.7 and 54.8 m 3 with an annual average of 42.4 m 3. The amount of daily O 2 formation also depends on the total gas formation and varies between 0.1 and 3.1 m 3, range with an annual average of 1.3 m 3. Avarage Daily Gas Amount (m 3 /day), Temp. ( o C) Total Gas CH4 CO2 Temp. O2 Time (Month) FIGURE 3 Distribution of daily produced average gas amounts in 2001 months. 977

6 DISCUSSION AND CONCLUSION When the measured monthly average methane concentration and volume were analyzed in the Istanbul Yakacik solid waste landfill gas combustion plant for the year 2001, it was found that the average annual concentration was 51 volume percent. Average daily methane formation amount was measured as 87.5 m 3 The annual CO 2 concentration average was found to be 24.7 % in volume. The daily average CO 2 formation was measured as 42.4 m 3. Not a great variation in CO 2 amount was noticed. It was also observed that the annual average O 2 concentration was 0.8 % in volume. The daily average O 2 formation was found to be 1.3 m 3. No great variation in the O 2 amount that arrives at the combustion plant has been noticed, and it could be stated that due to its low concentration, anaerobic conditions might have formed in the medium and that the air might have intruded into the landfill mass from atmosphere. Also no any significant variation has been noticed in the gas flow rate related to the seasonal temperature variation. Methane formation is greater in winter and less in summer; this may be attributed to soil fractures, which result in the widening of pore diameters and gas leakage as a consequence. Similarly, it can be said that the water in the waste content evaporates and, therefore, prevents the formation of anaerobic conditions. Another reason for the decrease in methane formation in summer might be that the water evaporates and leaves the medium. If the area was not used as a landfill before, this might result in improper gas leak even if the landfill has been rehabilitated. As a result, this combustion plant is useful, because it allows the explosive methane gas and other landfill gases that come out of anaerobic decomposition, to be burnt and destroyed, but also it was noted that the concentration of these gases was insufficient for energy production. [3] McBean, E.A., Rovers, F.A. and Farquhar, G.J. (1995) Solid Waste Engineering and Design. Prentice Hall PTR. New Jersey. [4] Bottomley, V. (1993) Monitoring of Landfill Gas. The Institute of Wastes Management s Technical Sub Committee. [5] El-Fadel, M. and Massaud, M.(2000) Emissions From Landfills: A Methodology Comparative Assessment. Environmental Technology 21, [6] Tchobanoglous, G., Theissen, H. and Vigil S.A.(1993) Integrated Solid Waste Management Engineering Principles and Management Issues. McGraw Hill International Editions, New York. [7] Mosher, B.W., Hzepiel, P.M., Harris, R.C., Shorter, J.H., Kolb, C.E., Mcmanus, J.B., Allwine, E. and Lamb B.K. (1999) Methane Emissions at Nine Landfill Sites in the Northeastern United States. Environ. Sci. Technol. 33, [8] Municipality of Metropolis Istanbul, Bulletin of Istanbul (in Turkish).No.145, Istanbul, [9] Nemlioglu, S., Demir, G., Borat, M. and Bayat, C. (2002) Landfill Gas Emissions of the Closed Solid Waste Dumping Sites Yakacik and Hekimbasi in Istanbul. ISWA 2002 World Congress&Exhibition, Appropriate Environmental Solid Waste Management and Technologies for Developing Countries. Istanbul [10] Gonullu, M.T. (1998) Umraniye - Hekimbasi Dumping Site Under Rehabilitated Condition Measurement Report (Environmental Directorship of Istanbul City,in Turkish). unpublished, Yildiz Technical University. [11] Bayat, C., Borat, M., Nemlioglu, S., Demir G. and Soyhan B. (2000) Landfill Gas Measurement in Solid Waste Landfill Sites of Istanbul (in Turkish), the Research Fund of the University of Istanbul. Project Report, P roject N o. 1139/010598, Istanbul. [12] Turkish State Meteorological Service, Ankara ACKNOWLEDGEMENTS This work was supported by the Research Fund of the Istanbul University (Project number: BYP-199/ ). Received: November 21, 2003 Revised: March 24, 2004 Accepted: May 06, 2004 REFERENCES [1] Demir, I., Altinbas, M. and Arikan, O. (1999) Integrated Management Approach for Solid Wastes (in Turkish). City Administration Human and Environment Problems 99 Symposium, Istanbul, [2] Toroz, I. and Arikan, O. (1999) Investigation on Solid Waste Recycling in Istanbul (in Turkish). City Administration Human and Environment Problems 99 Symposium, Istanbul, CORRESPONDING AUTHOR H.K. Ozcan Istanbul University Faculty of Engineering Department of Environmental Engineering Avcilar, Istanbul - TURKEY hkozcan@istanbul.edu.tr FEB/ Vol 13/ No 10/ 2004 pages