Energy Production From Solid Waste In Rural Areas of Province By Anaerobic Digestion

Edris Madadian, Leila Amiri+, M.Ali Abdoli, Saeid Gitipour, Hamed Hasanian

Department of Environmental Engineering, Faculty of Environment, University of Tehran, E-mail address: [email protected].

Abstract. By growing population and standard of living, the amounts I. INTRODUCTION of Municipal of Solid Waste (MSW) are rising steeply. Developing alternative energy source to replace traditional fossil fuel has As a consequence to the increasing number of recently become more and more attractive due to the high energy population and the improvement of living quality, the demand, the limited resource of fossil fuel, and environmental total amount of municipal solid waste is continuously concerns as well as a strategy to survive post-fossil fuel economy era. Biogas has become more attractive as an alternative to fossil fuel rising. In the present condition, all of the countries have because of its environmental benefits and the fact that it is made from a common problem, and it is replacing the unrenewable renewable resources. energy resources with the renewable energy resources. Anaerobic digestion is described as a series of processes involving Specially, the problems related to providing fuel for the microorganisms to break down biodegradable material in the rural areas and the shortage of fossil fuel resources has absence of oxygen. It occurs in three stages, hydrolysis/liquefaction, acidogenesis and methanogenesis. The overall result of anaerobic made them to consider biogas technology and its digestion is the biodegradable material into methane, carbon dioxide, development in Iran. Therefore it needs professional hydrogen sulfide, ammonia and new bacterial biomass. The correct planning for its development, and considering its development of anaerobic digesters can have several advantages, but positive social, economical, political and cultural effects. generally, it has been considered from three aspects which are as In this research rural areas of are follows: 2 - Biogas recovery for various applications selected. The Tehran case study covers 730 km areas - Successful handling of wet waste and is the capital of Iran. It is also Iran's largest urban - waste stabilization and reduction of landfill settlements area and Tehran features a semi-arid, continental - less emission of bad odor and green house gasses climate. - reducing contamination of the environment; II. METHODOLOGY In this research, we have performed case studies for the rural waste in the province of Tehran. The research showed that the usage of Review anaerobic digesters in this province, by considering the condition of Organic materials, livestock, human and vegetal this region, is more suitable and useful strategy for waste waste are degradable and under special condition, a part management. Batch system is selected for this purpose. The batch system would be right for developing countries for these are cheap of them can be fermented and converted to biogas which and easy to operate. In the batch system, digesters are filled once is composed of methane and carbonic gas [1,2]. The with fresh wet waste, and sealed for the complete retention time, after result of this reaction has invented some ways for which it is opened and the effluent removed. The results showed that converting waste to energy, which is known as biogas there are enough potential for the recovery of biogas from technology. The biogas production in digesters depends degradable waste in the rural areas of Tehran. Annually it can be extracted about 16100 million m3 biogas from the existing resources on several factors such as PH (between 6.8 to 7.2 is in the rural areas of this province, and provided the lighting, heating suitable[2]), Temperature (suitable temp is 37°C[2]), and cooking of the villagers from the biogas fuel. Type, concentration and the composition of raw Key Words: Anerobic Digester, Biogas, Rural Areas, Biodegradable materials (7 to 9% of the solution is suitable[3,4]). The Solid Waste, livestock waste lack of inhibitor and toxic elements in the biogas device (such as sodium, potassium, calcium, magnesium and iron), The detention time in the digester (The more the decay time, the more the gas production factor [4,5,7,9]).

Types of anaerobic digesters for organic solid wastes Typically Anaerobic Digesters (AD) or processes of The Usage Of Biogas Production From Anaerobic Digester In solid waste can be distinguished into several types, The Rural Areas Of Tehran mostly according to the feeding mode (continuous and The biogas is produced by the fermentation of three batch mode) and the moisture content of the substrate biological resources: (I)the livestock waste (II)municipal (wet or dry digestion). [8,11] and rural waste (III)domestic wastewater. In this research, the potentiometry of the biogas production in A. Wet and dry AD: digestions depending on the AD from the livestock and rural waste are discussed. total solids concentration of the feed substrate can be termed as “wet” (solids concentration <15%) and “dry” Table 1 presents the number and the type of the (the concentration >20–40%)[6,8]. livestock statistics with the statistics of the rural population in ten county of Tehran (2009). B. Batch and continuous feeding systems: In the batch system, digesters are filled once with fresh material and sealed for the complete retention time, after TABLE 1-THE STATISTICS OF THE NUMBER OF THE LIVESTOCK AND THE which it is opened and the effluent removed. In the RURAL POPULATION (2009) continuous system, fresh material continuously enters County Population livestock the digester and an equal amount of digested material is Tehran 93422 26310 removed. Damavand 23312 78799 The Necessity Of The Anaerobic Digesters Development In Rural Rey 193122 124581 Areas The usage of biogas technology will decrease the Shemiranat 14699 41771 consumption of fossil fuels and the problems related to 61479 105774 the transferring of fuel to the rural areas. And it is also a 100848 294998 good way to manage rural waste. On the other hand, job Savojbolagh 125007 133502 opportunities will be provided for a group of youth. The lack of rural roads makes the fuel transportation hard. Shahryar 154113 131887 The depth and the extent of the problems will be realized 44507 41498 if the ecological effects of fossil fuels in the Robatkarim 94516 36398 environmental contamination and the required costs for 94018 117496 compensating are estimated. Therefore the significance of the biogas technology will be recognized. Firozkoh 19396 115677 Nazarabad 28008 80868 A comprehensive economical analysis has to be performed in order to define a strategy of AD of Organic Fraction of Municipal Solid Waste (OFMSW). By using the statistics of the annual waste Furthermore, if the digestate of an AD has to be production for each livestock which is presented in disposed in a landfill, AD of OFMSW has advantages Table 2, the total production of waste in each county is such as: minimization of masses and volume, calculated separately. inactivation of biological and biochemical processes in order to avoid landfill-gas and odor emissions, reduction TABLE 2- THE ANNUAL LIVESTOCK WASTE PRODUCTION of landfill settlements, and immobilization of pollutants Type of Endemic Heterogeneous Purebred Goat Sheep in order to reduce leachate contamination [10]. Livestock cow cow cow Livestock According to the past researches, various models of waste 0.95 1.44 9 13.5 20.25 digester are known and established throughout the (tons/year) world. However, the AD is selected in this research[6,7]. This model is more compatible with the weather Since only a part of the calculated waste can be condition of Iran. According to the advantages and collected and used in biogas devices,the amount of the disadvantages of available digesters, the best biogas recoverable waste should be determined.The waste device model, is AD. recovery factor for each livestock is presented in Table3. One notable disadvantage of AD are the relatively long time requirements of the start-up period, a condition attributed to the slow growth rates of anaerobic bacteria.

TABLE 3- THE LIVESTOCK WASTE RECOVERY Type of Endemic Heterogeneous Goat Sheep Purebred cow Livestock cow cow TABLE 6- THE RECOVERY OF RURAL WASTE AND THE BIOGAS The waste PRODUCTION 0.2 0.2 0.5 0.7 1 recovery factor amount of Potential of biogas County recovery rural production waste (kg/day) (m3/day) In addition to the above factors, the weather Tehran 13416 1744 condition of the studied area is considered, which Damavand 3348 435 determines the energy production efficiency (Table 4). Rey 27733 3605 Shemiranat 2111 274 TABLE 4- THE VALUES OF THE PRODUCED RECOVERABLE WASTE AND Karaj 8829 1148 POTENTIAL OF THE BIOGAS PRODUCTION 14482 1883 recoverable recoverable Varamin Biogas County waste waste Savojbolagh 17951 2334 (m3/capita) (ton/year) (kg/day.capita) Shahryar 22131 2877 Tehran 759185 22.26 5.57 Eslamshahr 6391 831 Damavand 1504306 176.79 44.2 Robatkarim 13573 1764 Rey 11061681 156.93 39.23 Pakdasht 13501 1755 Shemiranat 134452 25.06 6.27 Firozkoh 2785 362 Karaj 2888309 128.71 32.18 Nazarabad 4022 523 Varamin 6836807 185.73 46.43 Savojbolagh 3761065 82.43 20.61 Shahryar 13445915 239.03 59.76 III. CONCLUSION. Eslamshahr 8605665 529.74 132.44 Robatkarim 4455969 129.16 32.29 In order to produce biogas in Tehran, the available Pakdasht 5311949 154.79 38.7 livestock waste is 64.4 million tons per year, and the 3 Firozkoh 185743.5 26.24 6.56 produced biogas is 16093 million m . The value of the rural degradable waste which can be used in biogas Nazarabad 5422472 530.42 132.61 devices in Tehran is 55 thousand tons per year, and its 3 produced biogas is 7.13 million m . It is seen that, 16100 In the second section, the biogas production million m3 biogas (9664 million m3 methane) is potentiometry of the rural waste is studied. The average recoverable from the above resources. If we assume that percentage of its components is presented in the Table 5. the thermal value of methane is 36.7 MJ/m³, this amount The average of the waste production in rural areas of of methane is equal to 3.5 ×10 11MJ energy. It can be is 323.96 g/day and its density is 255 kg/m3. concluded that the potential for biogas production from livestock waste is higher than the potential from the

degradable materials that exists in the rural domestic TABLE 5- THE AVERAGE PERCENTAGE OF WASTE COMPONENTS IN RURAL waste AREAS OF THE TEHRAN PROVINCE In most parts of Iran, not only these organic Component Paper Plastic Organic waste Metal Glass materials are not used, but also these materials are percentage 6.01 6.49 46.36 5.37 4.53 disposed and buried with a considerable cost. The Demolition Component Textile Wood Tire Other establishment and development of the AD in rural areas waste of Iran, is a reliable way for collecting and the optimal percentage 4.32 7.83 4.36 3.22 11.51 use of livestock waste

In the last decade of the 20th century, the use of AD In this section, the amount of recovery rural waste technology for the processing of organic wastes has and biogas production potential is calculated by expanded appreciably. In future, the best practicable considering the waste production per capita and the environmental option will be deriving energy from percent of the degradable rural waste in each county, and waste. Energy recovery technologies include combustion by applying the 70% factor for the possibility of the of waste and AD. However, combustion of the wet recovery of these produced waste in the rural areas as the stream of solid waste does not provide efficient energy raw material for the biogas production (Table 6). recovery. So the advantages offered by AD are worth

exploring for the wet stream of Solid Waste of rural areas in Tehran province and elsewhere. Considering the studied statistics, it can be concluded that in many parts of the rural areas in Tehran, the potential for the use of biogas exists, and only with suitable management and planning, we can take advantage of this endless resource. The use of biogas not only provides healthy environment, rich compost and fuel gas, but also it is important from the economical viewpoint.

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