Jhonatas Antonelli

Technical potential of electricity production from municipal solid waste disposed in the biggest cities in Brazil: Landfill gas, biogas and thermal treatment

This article presents an analysis of possibilities for electrical energy production by using municipal solid waste disposed in the biggest Brazilian cities. Currently, the municipal solid waste in Brazil is collected and disposed of at landfills, but there are also other technologies, which in addition to dealing with the garbage can also provide benefits in terms of energy provision. The following scenarios were studied in this work: electricity production from landfill gas (reference scenario); incineration of all municipal solid waste; anaerobic digestion of organic waste and incineration of refuse-derived fuel fractions after being separated in separation plants. According to this study, the biggest cities in Brazil generate about 18.9 million tonnes of municipal solid waste per year (2011), of which 51.5% is biogenic matter. The overall domestic consumption of electricity is 480,120 GWh y−1 in Brazil and the municipal solid waste incineration in the 16 largest cities in the country could replace 1.8% of it using incinerators. The city of São Paulo could produce 637 GWh y−1 with landfill gas, 2368 GWh y−1 with incineration of municipal solid waste and 1177 GWh y−1 with incineration of refuse-derived fuel. The latter two scenarios could replace 27% and 13.5% of the residential electrical energy consumption in the city. This shows that thermal treatment might be a viable option of waste-to-energy in Brazil.

Lead adsorption and subsequent gasification with Pinus elliottii waste

Purpose The purpose of this paper is to investigate the use of Pinus wood waste in lead adsorption as a remediation technique in aqueous medium and its subsequent use in obtaining synthesis gas. Design/methodology/approach The capacity of the timber in the lead adsorption was studied in aqueous medium at various pH, determining the amount adsorbed in equilibrium. Then, the same timber was added in a fixed bed, co-current flow of two stage gasifier type, working temperature of 900°C, for obtaining synthesis gas. The synthesis gas composition was evaluated by the spectrophotometry in the infrared region and the gas chromatography and lead content in the ash and gas was determined by the atomic absorption spectrophotometry. Findings In laboratory tests carried out, the optimal pH for lead removal was pH 4 with 96.15 percent removal rate, reaching equilibrium after 180 min. In pilot scale the lead removal after 72 hours was 96 percent. The average production of syngas was 11.09 m³h−1. For tests with the motor-generator, the best condition occurred with charge of 2.0 kW, wherein gas consumption per kW produced reached 4.86 m³ kW−1, resulting in a 14.81 percent efficiency rate. The gas analysis showed an average concentration of 14.85 percent H2, 30.1 percent CO2, and 50.49 percent of atmospheric air. The concentration of lead in the gas was below the limit established by law. Pinus elliottii waste proved to be an excellent adsorbent, with removing more than 96 percent of the Pb ion present in aqueous solution and a starting material in the gasifier to generate synthesis gas. Research limitations/implications This paper describes the waste wood application in the treatment of contaminated environments and for obtaining syngas providing a sustainable process. Originality/value This paper shows a process that combines the remediation of contaminated environmental with power generation systems, allowing efficient management of contaminated environments.

Biogas production with co-digestion of sugarcane straw

Purpose The purpose of this paper is to investigate straw modification by chemical degradation generated by two forms of pretreatment, using citric acid in an autoclave and urea solution with sodium hydroxide at low temperature. Design/methodology/approach The material was digested and compared in biodigester reactors lined with natural straw, straw pretreated with citric acid, straw pretreated with urea and NaOH, and straw subjected to both the pretreatments. The amount of straw has been delimited to 0, 2.5, 5, 7.5 and 10 percent v/v, and used 20 percent v/v inoculum in all reactors, consisting of 30 percent v/v poultry litter and 70 percent swine wastewater (SW). The experiment was conducted in an incubator kept in mesophilic conditions (35°C). Findings The results indicate significant change in the studied material, with degradation of lignin as well as hemicellulose and cellulose exposed to further hydrolysis. Spectrophotometric methods were used for monitoring degradation. These methods were efficient in monitoring changes caused by the treatments. When the proposed pretreatments are applied to sugarcane straw, there is a significant gain in biogas production (L g VSR−1). The most appropriate rates for higher methane production in the pretreatments are 2.5 and 5 percent straw-SW. The best results for the anaerobic digestion of sugarcane straw were obtained by pretreating it with citric acid. Originality/value This paper shows a new use for the sugarcane straw waste after being pretreated with acid or base for the coproduction of biogas.