Global Journal of Science Frontier Research, H: Environment & Earth Science, Volume 22 Issue 1

of civil works, including those resulting from excavation for land preparation and civil works; • Agricultural, arising from the productive activity of the primary sector. • Transport services waste, those originating from ports, airports, customs, road and rail terminals and border crossings; or • Mining waste, those generated in the activity of research, extraction or mineral processing In this article, only urban solid waste will be treated. According to ABRELPE [3], the total ammount of waste generated in Brazil in 2019 was 79 million ton/year. About 92.0% of this total was collected. The Fig. 1 compares the percentage of waste disposal that had an adequate final destination (landfills) and inadequate final destination (disposed in controlled landfills and dumps), concluding that about 5 million ton/year were still not collected. Fig. 1: Final destination of MSW collected in Brazil in 2019 (ton/year) [3] The initial deadline of the PNRS for the municipalities eradicating irregular landfills and effectively implemented the solid waste management expired in 2014. In 2020 a new deal was established: all capitals and metropolitan regions must eliminate dumps until August 2021; cities with more than 100,000 inhabitants have until August 2022 and for those with less than 100,000 inhabitants the deadline is August 2024. Recycling collection and material separation are significant components of MSW minimization. However is important to highlight that only 73.10% of the municipalities carry out selective waste collection as shown in Fig. 2. Fig. 2: Selective waste collection in municipalities in 2019 – Regions and Brazil [3] b) The problem of urban solid waste and its energy use The decomposition of materials could generate toxic gases that contaminate the soil, water, air and population [3], so the inadequate destination of residues is responsible for serious environmental impacts. Disposal in landfills remains the main form of MSW disposal method. However, it is known that landfills are major contributors to the emission of GHG. An alternative to minimize its effect is the energy use of MSW for energy generation [4]. Solid waste gases are composed of 50% to 60% methane (CH 4 ), 40% to 50% carbon dioxide (CO 2 ) and smaller proportions of other gases such as ammonia (NH 3 ), hydrogen (N 2 ) and oxygen (O 2 ) [5]. These gases are generated during the decomposition of organic matter that occurs by two processes: aerobic decomposition, from the final disposal of waste in the landfill, and anaerobic decomposition, due to the reduction of O 2 . CH 4 and CO 2 come from anaerobic decomposition [6], both are responsible for GHG emissions. CH 4 is the second most important GHG emissions, after CO ₂ and its global warming potential is 21 times greater than CO ₂ [7]. Therefore it is fudamental analyzing the feasibility of implementing plants for the energy use of MSW as an environmental alternative and as a business opportunity. Incineration and biological processing of MSW are examples of energy use that can drastically reduce the area needed for landfills [6]. Recycling is also considered an efficient form of energy use, as it allows the recovery of raw materials used in the production process, where energy consumption is normally higher. The energy use from biogas, commonly known as landfill gas (LFG), can be used in two ways: as a substitute or complement to natural gas, in this case a purification process is need [8], or as electricity generation that will be the object of this study [6]. c) Electricity generation from biogas The energy use of biogas for electricity generation requires the installation of equipment to operate and monitor the system as shown in Fig. 3. © 2022 Global Journals 1 Year 2022 54 Global Journal of Science Frontier Research Volume XXII Issue ersion I VI ( H ) Energetic Potential of the Biogas from Urban Solid Waste Generated in the Jacareí Municipal Landfill, Brazil