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Energy from Waste: Case Study from Brazil T. CÁSSIADE BRITOGALVÃOlANDWILLERH. Pos,2 lSchoolof Engineering-FederalUniversityof Minas Gerais,Av. Contorno842/104, 30110-060, Belo Horizonte, Brazil 2Instituto Mineiro de Gestão das Agusa-Head Rua Santa Catarina, 1354, 4° andar, 3070-081, Belo Horizonte, Brazil

Introduction A growing concern of environmental issues is a very important characteristic of the last 40 years in the whole world. This concern is well justified by the immediate problems: population growth, depletion of productivity of agriculturallands, watershed management, high-carbon energy system, climate changes, and waste management practices. In the past few years some conferences proposed by the United Nations had discussed some of the immediate problems left to be solved in the next millennium, and described above: Earth Summit-92 in Rio, Population growth in Cairo (1994), the future of cities in Istanbul in 1995. AIso, in 1995 about 500 diplomats from 130 countries gathered in Berlin to negotiate an agreement for climate protection. In 1996, climate researchers had pointed out that the floods in China, and the third greatest drought in America, in this century, are the trigger mechanisms for the next climatic geohazard: deicing of the poles and the heightening of the sea leveI, as consequences of the great amount of polluted gas in our atmosphere- (COz' CFC -clorofluorcarbon, methane and nitrous oxide). In Brazil, the clean technologies have been developed mainly due to economical needs. An example is the Alcohol Program, developed due to Petroleum Crisis, which increased the price of a barrel in four times, in 1973. However, a research done in 1998 by the Brazilian Institutions "Confederação Nacional da Indústria (CNI), the Banco Nacional de Desenvolvimento Econômico e Social (BNDES) and Sebrae", named "Research of Environmental Management in Brazilian Industry", showed that about 75% of the companies intend to invest on environmental research; 90% of the biggest companies and more than one third of the microcompanies invested in the environmental sector in 1997, and more than 39% of those companies used Brazilian consultants. This research shows the growing concern towards environmentally clean technologies, that means, lower consumption of materiaIs and energy with lesser environmental impacts. At present, the modern industrial societies of the big cities need great amounts of petroleum for mass transportation, but future societies won't be able to count on this form of energy and, probably,

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would rely on solar, nuclear or thermonuclear energy, or develop methods to use energy from waste in a more efficient and economical way. In the particular case of Brazil, preservation of our environment should be a national priority due to the fact that a third of all tropical forests and biodiversity af this planet are located in Brazil. Developing technologies based less on fossil-fuel, which produce less greenhouse gas emissions and developing more technologies based on the principIe of the "clean-burning economical technologies" to preserve our environment, is an imperative need for the country. This chapter encloses a state-of-the-art from the Brazilian experiences and developments on clean technologies and on the potential to develop clean technologies regarding energy production, which contemplates much more the environmental needs than the economical needs. An emphasis is given on the Brazilian Experiences on Biomass and Landfilling Process and on the Use of Landfill Gas. A1though those technologies benefit the environment, and represent a necessary condition towards safe life conditions in this planet, they hardly will shake the billionaire electric power industry - one of the world's largest-in the next few years. For the next 7 years, the Brazilian Govemment plans to invest about US$ 1.7 billion dolIars in the construction of transmission lines for electricity, about 0.7 billion dolIars in the construction of gas conduits, about 10 billion dolIars in therma electrical power plants and about 15 million dolIars in the construction of hydro electrical power plants. No money for alternative sources of energy has been planned, so faro

Traditional Sources of Energy in Brazil Brazil is a country rich in water resources (more than 12% of the available water resources of this planet), mineral resources, plants resources and renewable forest resources. Besides petroleum and its derived products we have: firewood; vegetal and mineral coal; sugarcane which gives us alcohol; "babaçu" plant, turf, vegetal residues, biogas, uranium, etc. TraditionalIy, the energy for the growing Brazilian market was provided by harnessing its water resources potential, by means of constructing dams. Hydroelectric power plants cater to 92% of alI energy requirements and produce about 65, 000 MWatts/hour. The majority of the Brazilian population and industries are located in the south and southeastern regions. The hydraulic potential of the region is welI utilized, to the tune of > 80% via power harnessed from the rivers Paraná and São Francisco. What remains to be used for the next generation is less than 17%. The only region in the whole country, which remains to be explored, is the Amazonas. However, the nega tive environmental impacts of exploiting water resources of the region outweigh the benefits and the endeavour to do so. In order to fill a dam water reservoir it is necessary to fIood extensive areas of forest killing most of the existing biodiversity. It requires also, fIooding agriculturallands, villages and smalI cities, as welI as displacing entire populations to other areas. The cultural and social costs involved in such activities are hardly greater than the advantages that a hydraulic power plant might offer. As an example, we have the hydraulic power plant of Balbina in the Amazonas region, which emits to the atmosphere a great amount of methane due to the biodegradation of the fIooded biomass of the forest in an effect similar to a thermo-electric power plant of similar capacity. Also,

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Energy trom Waste: Case Study trom Brazil

it is known that in São Paulo, the thermo-electric power plant of Piratininga alone praduces more sulfur dioxide than alI the public transportation. The second source of energy is petroleum, and Brazil is presently a world leader in extracting petroleum from great depths (more than 1000 m) and produces a total amount of 1,108,000 barrels a day. The third source is natural gas and it represents 2.6% of the total energy matrix. It comes from national beds and from Bolivia, through conduits calIed "Gasoduto Bolívia-Brasil". It is estimated that Brazil will receive about 16 million m3/ day from Bolivia and could reach a maximum of 30 million m3/ day. In 1996, the natural gas reserves in Brazil were of the orderof 157.7 billion m3. With the gas importation fram Bolívia, the goal is to go from 2.6% to 12%, of the total Brazilian market, by the year 2010. In Brazil's energy planning, for 2001, it is predicted a 10% rise in the natural gas consumption. Although gas is basicalIy transported by conduits in its gaseous state, it could be transported in liquid state, where its volume is reduced about 600 times, by diminishing its temperature to -160°C. Natural gas is basicalIy a compound of light hydrocarbons and in the standard conditions of temperature and pressure its natural state is in the form of gas. Although the chemical composition of natural gas varies, it is a compound of methane, ethane and propane. UsualIy, it is found in underground reservoirs associated or not with petroleum. If it is mixed with petroleum, we have the natural associated gas. The non-associated gas is characterized by the absence of oil or in very smalI amounts. In smalI amounts, one can find in its composition nitrogen, carbondioxide, and sulphur. Natural gas is odourless, colorless, inflammable, and suffocating. Then, as a matter of safety, the gas is impregnated with sulphur, to identify its presence by the odour, and has no corrosive properties. The components of associated and non-associated gas are presented in Table 13.1. Table 13.1. Gas composition Components . Methane Ethane Propane Isobutene Butane Isopentane Pentane Hexane Heptane and above Nitrogen Carbon dioxide Density

Associated gas (%) 81.57 9.17 5.13 0.94 1.45 0.26 0.30 0.15 0.12 0.52 0.39 0.71

Non-associated

gas (%)

85.48 8.26 3.06 0.47 0.85 0.20 0.24 0.21 0.06 0.53 0.64 0.69

Source:Petrobras

Alternative Sources of Energy The petroleum crisis of 1973 promoted a global awakening towards the fact that this is an exhaustible source of energy. In 1976, in Brazil, began researches on the

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development of alterna tive sources of energy, the most successful is the Alcohol Program that will be discussed later. The other alterna tive sources of energy comprise solar energy, wind energy, tide energy, and biomass energy. Although a high amount of solar radiation is received in the country, specially the north and northeastern States, this potential is hardly exploited for heating purposes. COELCE-Brazilian Company of Electricity of Ceará has inaugurated a great wind plant in Fortaleza, which intends to generate 3.8 million kW /h annually. In 1987, CHESF- Company Hydroelectric of São Francisco commissioned a research to gauge the solar potential in the northeastern regions of Brazil, and this research showed that the entire region promises a high solar potential of about 11,400 MW /year in an area of 1000 km2. The optimal utilization of such a natural resource needs to be addressed. From 1976 unti11980, the Brazilian Electrical Company, Eletrobrás, and the Navy Ministry have conducted studies in Maranhão and Pará shores for installation of a tide-energy powered plant at the mouth of Bacanga River, in São Luís do Maranhão Island. Studies have shown 42 potential places to be at very advantageous positions. Among the cited advantages of such tide powered plants, were the development of renewable environmentally clean sources of energy, total independence upon the precipitation conditions of that region, the cost of the energy staying constant in the same life time of the equipments, and finally, the basin being natural, does not require any flooding of additional areas. The studies have also shown the potential of installation of a 36,000 MW tide-power plant. In the studied regions the tides are 5-8 m high, and could rise to 13 m. Biomass energy is produced direct1y through the burning of wood, pulps, peels, residues and cakes or through the production of gases in biogestors. The gas produced by the burning of biomass c?uses lesser environmental impact than the pollution of hydroelectric power plants. In Brazil, the babaçu plant is considered to be an excellent fuel and can substitute coke in the steel industry and combustible oil in cement industries. The states of Maranhão and Piaui have great Brazilian potential in babaçuplants. It is important to point out that there are some research areas that need to be investigated before the development of a wider biomass energy program, these are: . a global rising of the potential of electricity generated by biomass and urban solid wastes in different parts of the country; government subsidies on biomass and urban solid wastes power plants also on transportation and distribution to the other regions of the country as well discounts on taxes and equipments; and minimal degree of efficiency for generation and co-generation of energy from biomass, encouraging technologies into the market.

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Alcohol Program Brazil has successfully developed the greatest worldwide program of utilizing in large scale, biomass in the form of sugarcane transformed in alcohol, which can be used as car combustible. It is important to point out the existence of technology for fabricating automobiles moved by hydrated alcohol. From the Brazilian point of view this is a very important program due to the following reasons: (i) it helps to save fossi! combustible, (ii) it gives employment to people with lower levels of

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education; (iii) it reduces air-polIution. At the Fourth Meeting of Renewable Sources ofEnergy, held at Recife (October, 1998) they carne to the folIowing recommendations, which would significantly reduce greenhouse gas emissions and be beneficial for the economy, The gradative introduction of alcohol mixtures in Brazilian diesel The immediate decision of adding 2% anidro-etilic alcohol carburant into diesel oil, folIowing recommendations of several international producers of diesel motors. This mixture is considered anti-freezing. The establishment of goals and procedures based on research observations, to set levels (above 2%) af optimized mixtures, by use of anidro or hydrated alcohol, by means of stabilizer, which could be co-solvent or emulsion. The above recommendations are based on the folIowing considerations, among others:

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This country spends, 900 million dolIars, annualIy, importing 15% of diesel oil, which it needs Diesel motors contribute to the emission of a black smoke and other polIutants, which polIute major Brazilian cities The Brazilian society has invested great amounts of money in a national program of substitution of fuel by alcohol. Today, this program is responsible for more than 1 million jobs; That the addition of ethanol in diesel could be a way of stabilizing the seasonal fluctuations in diesel supply and demand; That it is possible to admit as a fact that the optimized use of mixtures alcohol-diesel can help in reducing the particulates in about 35%, the carbon monoxide and hydrocarbons in about in 15%; sulphur oxides in 10% and nitrogen oxides in 5%.

Biogas Production from landfills Landfills are a great source of methane emission, which is one of the principal greenhouse gases. After EPA (1996) methane is responsible for roughly 18% of the total contribution. Biogas is generated by the biodegradation of organic matter from vegetal or animal origin by anaerobic microorganisms. As an end product of this biological process one can have a gas composed of methane (CH4) and carbon dioxide (COz) known as biogas. Anaerobic processes could either occur naturalIy or in a controlIed environment such as a biogas planto Depending on the type of waste and the system design, 55 to 75% of pure methane can be obtained from biogas. The process of anaerobic digestion consists of three steps: (i) the first step is the decomposition (hydrolysis) of organic matter, where higher molecular mass compounds (e.g.lipids, polysaccharides, proteins and nucleic acids) are transformed into intermediate mass compounds, which are much more suitable for the microorganisms as source of energy and celI carbon; (ii) the second one is the conversion of decomposed matter to organic acids-in this phase, the existing microorganisms convert the intermediate-molecular mass compounds into lower-molecular mass compounds such as acetic acid, smalIer concentrations of fulvic acids, and other complex organic acids; and the (iii) third is the acetic acids getting converted into methane gas-in this phase anaerobic microorganisms transform the acetic acid into mainly CH4 and COz gases.

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Gas amount and composition is thus supposed to vary according to many factors. However, parameters such as waste composition, operational procedures, temperature, humidity, pH, Eh' are those that mainly impact production of gases and composition. Biogas praduction is aIs o a function of the presence of micraorganisms capable of degrading the arganic matter in an anaerabic way. If the folIowing factors such as low temperatures, presence of air, excess of water, are contralled, then one can expect a stable production of biogas. In order that the solid waste receives a small impact from the environrnent, it is advisable for the cell to have a minimum height of 10 m and a daily solid waste disposition of more than 100 t. ln general, it is estimated that a landfill can produce biogas in an amount that varies fram 200 to 300 l/kg. However, Brazil is estimated to produce about 50 to 80 m3/ton biogas fram solid waste, in 10 years, approximately. ln Brazil, the gas produced by anaerobic digestion of organic vegetal residues represents a technology meant for public consumption and has been applied specially in the northeastem Brazil, where more than 300 unities were distributed in the State of Maranhão, Ceará, Pemambuco, Paraíba and Bahia. The greatest poential to be exploited is the agricultural activities, and besides, tapping energy from the gas, fertilizers could also be obtained. Solid Waste Facilities in Brazil Brazil produces about 0.2 million tons of solid waste a day. 76% is placed in open dumps, such as erosional are as, 13% is placed in controlled areas, 10% is placed in sanitary landfills, 0.9% presents a composting plant (or anaerobic digestor), and 0.1% has an incineration power plant (IPT, 1995). "Landfilling" is not the main method for disposal of municipal and household solid wastes or refuse in Brazil, as , shown by the statistics. The country has 4,974 municipal districts (IBAM, 1993), fram them 3,611 have less than 20,000 inhabitants, and the 21 biggest municipal districts (population bigger than 0.6 million people) have a total amount of 34 million inhabitants. Only 37 municipal districts in the total of 4,974 have facilities for anaerobic digestion (composting plant). In 1990, 17 of those 37 facilities were elosed or disabled, five were under annually, about construction and 15 were operational. The reasons (IPT, 1995) to elose ar disable those facilities were, among others: Bad planning of the installations, through credit given by the National Bank of Development-BNDES, which brought dispute among the constructors, who did not take into much considerations the real needs of the municipal districts; Total absence of management training in order to conduct the activities better; lnadequate placement of the landfills; Absence of financial integration and operation between the landfill and the Public Service of Urban Cleaning.

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Assuming

that 60% of the total generated

million ton/day,

solid waste

in Brazil is organic

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this organic waste would generate about 2,160 MW of energy.

Main Composition of Solid Waste As an example, Table 13.2 shows the solid waste composition of Belo Horizonte, the fourth biggest city in Brazil, especially because its composition has not varied along last years. One can observe that the waste composition in Belo Horizonte's landfill

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has a very small percent of paper, due to an intensive program, which involves a great amount of people, in separating paper before reaching the landfill facilities. The bulk density of this waste is 254 kg/m3. The landfills of the rest of the country have a great composition of paper of about 25%, organic matter about 52%, glass about 1%, glass about 1%, plastics 12% and 6% of others. Table 13.2. Solid Waste Composition from Belo Horizonte Landfill (Source: SLU, 2000) Material Organic matter (%) Paper (%) Cardboard (%) Plastics (%) Cans (%) Glass (%) Textile (%) Gum(%) Metais (%) Wood (%) Leather (%) Tiles and stones (%) Solid (%) Others (%) pH Volatile solids (% dry weight) Carbon (% dry weight) Nitrogen (% dry weight) PzOs (% dry weight) CaO (% dry weight) Mg (% dry weight)

Amount 54.06 12.50 6.00 5.90 2.70 3.15 6.20 1.07 0.60 1.30 1.09 1.60 2.50 1.33 5.3 72.00 38.00 1.03 1.30 2.30 1.02

Biogas Collection Systems The biogas generated by landfills is either extracted through a collection system drilled into the waste, after which it is treated and stored, or it undergoes combustion by flare. The gas collection system consists of a series of wells drilled into the landfill and connected by a plastic piping system. The collection systems for biogas mainly used are: collection in the drainage system for liquids extraction by means of probes extraction by perforated wells collection on the edges of the cell collection by using horizontal drains The collection used mostly in Brazil is ma de by means of drains at the inoculation points, to check through the gas composition the stage of biodegradation of the landfill. Table 13.3 shows a typical composition of the biogas (the low-Btu) from Brazilian landfills.

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Table 13.3. Gas Composition of Brazilian landfills. Methane Carbon dioxide Nitrogen Oxygen Sulphuric acid (H2S) Organic Sulphur

15-80 % 35-45 % 3-8 % 0-16 % 5.6g/m3 0.317/100 m3

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To purify the biogas, some usual procedures are used: For separating methane from carbon dioxide, in arder to improve the combustion power of methane, biogas is saturated with water, and that water must be removed prior to further processing. The amount of water used is about 460 liter for 1 m3 biogas (assuming that the amount of COz is 35% and at standards conditions of pressure and temperature, which are 1 atm and 20 °c). When the pressure is increased and the temperature is lowered, the solubility conditions improve, but the residual water become very acidic, and cause corrosion. The following treatment could also be used: Ca(OH}z, organic solvents such as monoethanoamine, diethanoamine and tri-ethanoamine, etc. The second step is to remove sulphur dioxide from the gas since it results in corrosion within the combustion equipment. The most economical way of removing the sulphur dioxide is thraugh filings af iron, which is regenerated after air exposure for 3-4 days. The almost pure methane (without CO, HzS, Oz, Nz and hydrocarbons) can be obtained through the use of molecular panels.

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TheExperienceof BeloHorizonte The city of Belo Horizonte

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is the fourth largest city in Brazil with an average population of 2.3 million. About 4464 t solid wastes is generated daily and collected by the Municipal Services. Only about 2000 ti day of solid waste is placed in landfills, the rest in recycled or re-used, upon arrival in the landfill area. The solid waste facility occupies an area of 144 ha, and has 5 cells. The final average height of each cell is about 50 m. The cell 5 corresponds to an old open dump, which people have been using since 1973 to dispose their garbage, and has no impermeabilization or gas layer. The others cells received an impermeabilization layer and are much more controlled and monitored. The waste treatment and disposal are done through a more controlled unit (cell 2); its leachate is collected and used for the bioremediation process of the cell5. This process was proposed by a local enterprise (LM, 1998) and is intended to accelerate the production of methane (CH4) and carbon dioxide (COz). It is based on the treatment, inoculation and recycling of leachate enriched with specially developed bacteria by LM (1998), capable of acquiring the final stabilization of the wastes within three years, followed by the mining af reusable materiaIs and liberating the area for the treatment of new wastes. Figure 13.1 shows the Belo Horizonte Landfill area, and photos 2 to 3 show the cell 2 in 1992 e 1998, respectively. This cell has dimensions of 200 x 200 mZ. Figure 13.1 presents a view of the landfill, with its five cells, and the location of the leachate and composting plants.

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The biegas was collected by the gas company Gasmig, treated and stored in cylinders, until1995. Nowadays, this service was suspended and the gas is simply combusted in a fiare system showed in Photo 3.

Belo Horizonte Landfill

Fig. 13.1 View of the Belo Horizonte's landfill.

Carbon dioxide and methane analysis was performed by a gas-chromatographic system containing a thermo-conductivity detector (TCD). The chromatograph consisted of a PE-Autosystem unit held at a constant temperature of 50°C. Helium was used as a carrier gas at performed at the Laboratory of Sanitary Engineering frem Engineering School-Universidade Federal de Minas Gerais and the average results are shown in Table 13.4 for cell 2.

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Photo 13.1 Cell 2, in 1992

Photo 13.2 Cell 2 in 1998 Table 13.4. Results of Methane and Carbon Dioxide frem Cell 2 Methane Carbon dioxide

35-55% 20-45%

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Photo

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13.3 Global view of cell 2, in 1998

Photo 13.4 Fiare of cell 2 REFERENCES

1. Balderrama, L. (1993).Estudo de impacto ambiental causado por aterro sanitário via migração de gases. Master Program Dissertation, UNICAMP, 79 pp + annexes. 2. Engelman, R. (1994). Stabilizing the atmosphere: population, consumption and greenhouse gases' - Population and Environmental Program, Population Action International, 47 pp. 3. IBAM (1993). Instituto Brasileroi de Municipios. Relatório Interno. 4. IPT (1995). Instituto de Pesquisas Tecnológicas de São Paulo. Lixo Municipal. Manual de Gerenciamento Integrado, 1st Edition, IPT: CEMPRE, S.P. 5. LM Tratamento de Resíduos (1998). Implantação do Aterro Celular da Central de Tratamento de Resíduos da BR-040--Projeto Básico. Belo Horizonte-MG. 6. Monitoramento Ambiental do Aterro Sanitário da BR-040 - 1°, 2°, 3°, 4°, 5° RelatóriosConvênio SLU/FCO (DESA-ETG)-Ago/98-Dez/99-Belo Horizonte-MG.

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7. Parker, A. (1983): Chapter 7. Behavior of Wastes in Landfill Leachate. Chapter 8. Behavior of Wastes in Landfill Methane Generation. In: Practical Waste Management, J. R. Holmes (ed.), John Wiley & Sons, Chichester, England. 8. Palmisano, A. and Barlaz, M. (eds.) (1996). Microbiology of solid waste. In: CRC Press, Boca Raton (USA), 224 p. 9. Poh!and, F.G. (1987). Critica! Review and Summary of Leachate and Gas Production from Landfills. EPA/600/S2-86/073, U.S. EPA Hazardous Waste Engineering Research Laboratory, Cincinnati, OH.

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