ABSTRACT
RESUMO O gerenciamento de resíduos sólidos urbanos, com a disposição do material em aterro sanitário, é uma prática amplamente adotada no Brasil. A quantificação do desempenho ambiental do gerenciamento de resíduos sólidos urbanos apoia a proposição de práticas otimizadas. A avaliação do ciclo de vida foi aplicada para avaliar o gerenciamento de resíduos sólidos urbanos de 1 tonelada de material em Feira de Santana, estado da Bahia, Brasil. A fronteira do sistema do gerenciamento de resíduos sólidos urbanos deste estudo incluiu o material gerenciado nas etapas de coleta, transporte, tratamento, disposição e manejo do lixiviado. Foi avaliada a disposição do material em aterro sanitário no cenário base de gerenciamento de resíduos sólidos urbanos e opções de recuperação de recurso para o aproveitamento de material (reciclagem e compostagem) e energia (aterro sanitário e digestão anaeróbia com coleta de biogás) nos cenários propostos de gerenciamento de resíduos sólidos urbanos. O inventário de primeiro plano utilizou dados representativos para os cenários avaliados, enquanto o inventário de segundo plano utilizou a base de dados ecoinvent™ no software Simapro®, com os métodos de demanda de energia acumulada e Intergovernmental Panel On Climate Change 2013, com potencial de aquecimento global de cem anos. A demanda de energia acumulada foi 215 MJ·t-1 e as emissões de gases de efeito estufa foram 449 kg CO2eq·t-1 no cenário base. A maior contribuição da demanda de energia acumulada do cenário base foi oriunda da etapa de coleta e transporte, enquanto aquela de gases de efeito estufa foi oriunda do aterro sanitário. Os cenários propostos com a recuperação dos recursos apresentaram potenciais de redução da demanda de energia acumulada e das emissões de gases de efeito estufa do gerenciamento de resíduos sólidos urbanos, assim como apoiam a transição para uma economia circular.
ABSTRACT Municipal Solid Waste Management with the material disposal in landfills is a widely adopted practice in Brazil. The environmental performance quantification in MSWM supports the proposition of optimized practices. The Life Cycle Assessment was applied to evaluate 1 ton of material in the Municipal Solid Waste Management of Feira de Santana, state of Bahia, Brazil. The system boundary of the Municipal Solid Waste Management in this study included the material managed in collection, transportation, treatment, disposal and leachate handling stages. The material disposal in sanitary landfill was evaluated in the base scenario of Municipal Solid Waste Management and the resource recovery options for material (recycling and composting) and energy (sanitary landfill and anaerobic digestion with biogas collection) in the proposed scenarios of Municipal Solid Waste Management. The foreground inventory used representative data for the evaluated scenarios, while the background inventory used the ecoinvent™ database in the Simapro® software with the Cumulative Energy Demand and Intergovernmental Panel on Climate Change 2013 with 100 years global warming potential methods. Cumulative Energy Demand was 215 MJ·t-1 and Greenhouse Gas emissions were 449 kg CO2eq·t-1 in the base scenario. The largest contribution in the base scenario was the collection and transportation stage in Cumulative Energy Demand and the sanitary landfill in Greenhouse Gas. The proposed scenarios with resource recovery showed a potential to reduce the Cumulative Energy Demand and Greenhouse Gas emissions in Municipal Solid Waste Management, along with supporting the transition to a circular economy.
ABSTRACT
RESUMO O objetivo do trabalho foi avaliar a operação e manutenção de um sistema de esgotamento sanitário centralizado, composto de três subsistemas, que atende 367 mil habitantes no Nordeste do Brasil. A avaliação do ciclo de vida considerou um inventário amplo de operação e manutenção do sistema de esgotamento sanitário com as redes de coleta, estações de tratamento de esgoto, disposição do esgoto tratado no corpo hídrico e gestão do lodo. O arranjo tecnológico das estações de tratamento de esgoto avaliadas incluiu o reator do tipo upflow anaerobic sludge blanket, seguido de lagoa aerada e lagoa de polimento em um subsistema, e upflow anaerobic sludge blanket seguido de reator de lodo ativado por aeração prolongada em dois subsistemas. O desempenho energético utilizou o método de demanda de energia acumulada e a pegada de carbono empregou o método de potencial de aquecimento global de 100 anos do Painel Intergovernamental sobre Mudanças Climáticas. O sistema de esgotamento sanitário avaliado demandou 5,12 MJ·m−3 e emitiu 4,08 kg CO2eq·m−3. As maiores contribuições do sistema de esgotamento sanitário avaliado foram a eletricidade, com 62% da demanda energética, e as emissões diretas para o ar, com 94% da pegada de carbono, sendo as emissões dos reatores upflow anaerobic sludge blanket com 76% da pegada de carbono. A identificação dos aspectos e impactos ambientais do sistema de esgotamento sanitário avaliado apoia a inovação tecnológica e gerencial para otimizar o desempenho energético e mitigar as emissões de gases de efeito estufa.
ABSTRACT This aim of this work was to evaluate the operation and maintenance of a centralized wastewater treatment system, composed of three subsystems, which serves 367 thousand inhabitants in northeastern Brazil. The life cycle assessment considered a comprehensive inventory of the wastewater treatment system operation and maintenance with the collection networks, wastewater treatment plants, disposal of the treated wastewater in the water body and sludge management. The technological arrangement of the evaluated wastewater treatment plants included the Upflow Anaerobic Sludge Blanket reactor, followed by aerated and polishing ponds in one subsystem, and Upflow Anaerobic Sludge Blanket followed by extended aeration activated sludge in two subsystems. The energy performance used the cumulative energy demand method and the carbon footprint used the global warming potential method for 100 years of the Intergovernmental Panel on Climate Change. The evaluated wastewater treatment system presented 5.12 MJ·m−3 and 4.08 kg CO2eq·m−3. The largest contribution of the evaluated wastewater treatment system was the electricity use with 62% of the energy demand and direct emissions to the air with 94% of the carbon footprint, being direct emissions from Upflow Anaerobic Sludge Blanket reactors with 76% of the carbon footprint. The identification of environmental aspects and impacts of the evaluated wastewater treatment system supports technological and management innovations to optimize its energy performance and mitigate greenhouse gases emission.
ABSTRACT
Potassium (K), along with nitrogen and phosphorus, is an essential resource to ensure agricultural productivity and, therefore, food security around the world. However, diminishing physical reserves of potash salts and high-price volatility of potassium chloride, the main source of K to agricultural soils, has raised concerns about a K scarcity scenario, mainly in countries that depend on fertilizer imports to sustain its production. In this context, Brazil is one of the main agricultural producers in the world, having a major role in the global K flows, since the country sustains its production by a high consumption of imported K fertilizers. In order to seek opportunities to contribute to a more sustainable management of K resources, tools such as the material flow analysis (MFA) can be used to highlight the main K stocks and flows in a country scale, and identify options for reuse and recycle. This study proposed a MFA of K for Brazil, considering the base-year 2013. A total of forty-four flows and seven stocks were identified and quantified considering nine main processes related to human activity. According to the results, for the year of study, the main inputs of K in Brazil were in the form of fertilizers (4.1 × 103 Gg of K per year), and the main outputs were in the form of grain exports (9.1 × 102 Gg of K per year). Agricultural soils were the main stock for K in the country, and from the total flow of 7.3 × 103 Gg of K per year applied to soils, 67% came out as agricultural products, 13% was lost through erosion and leaching, and 20% remained in the soils. The flow of K actually consumed by the Brazilian population was 3.5 × 102 Gg of K per year, just 8.4% of the total food produced in the country. About 1.9 × 103 Gg of K per year has been lost to the environment in sewage streams and solid landfill waste. Prospects for more sustainable K management in the country are identified and discussed.
Subject(s)
Fertilizers , Potassium , Agriculture , Brazil , Humans , Phosphorus/analysis , SoilABSTRACT
This manuscript aimed to identify the energy demand, and environmental aspects and impacts of crop fertilisation with human urine when compared to using mineral fertilisers. The Material Flow Analysis and Life Cycle Assessment methods were adopted covering the options from "cradle to grave". The fertilisation with human urine included the collection, storage, transportation, application and field emissions, while the fertilisation with mineral fertilisers included primary production of fertilisers, transportation, application and field emissions. The reference flows were based on the fertilisation of 1â¯ha of maize with 225â¯kg of nitrogen, 29â¯kg of phosphorus and 48â¯kg of potassium oxide. We analysed the environmental aspects such as nitrogen and phosphorus mass balance, energy demand and water depletion, as well as environmental impacts such as global warming, human toxicity, photochemical ozone formation, acidification, eutrophication, freshwater ecotoxicity, water scarcity and resource depletion. The agricultural fertilisation with full volume of human urine closer to the source presented smaller energy demand and environmental impact indicator values when compared to solid mineral fertiliser, despite the uncertainties. The fertilisation with human urine was more advantageous with transportation distances up to 134â¯km (energy demand) and 84â¯km (environmental categories) by truck compared to 1841â¯km of mineral fertiliser. Ammonia volatilisation control was key to reduce acidification and eutrophication indicator values. When considering additional gains such as the reduction of water demand and wastewater generation from a waterless collection of human urine, the indicator values of environmental aspects and impacts of fertilisation with human urine were smaller than those with mineral fertiliser and reached a break-even point of 193â¯km (energy demand) and 185â¯km (environmental categories). The nutrient cycling through resource-based sanitation offers an opportunity to expand sanitation access with smaller environmental impacts and more efficient water-energy-nutrient nexus.
Subject(s)
Fertilizers/analysis , Brazil , Humans , Nutrients , Wastewater , WaterABSTRACT
The change in nitrogen balance causes many environmental and socioeconomic impacts. In relation to food production and nitrogen release in wastewater systems, wastewater and sludge discharge and mineral fertilizer use intensify nitrogen imbalance of a region. The replacement of mineral fertilizer by nitrogen from treated wastewater, biosolids, and treated urine is a promising alternative. This work presents a model to support decision taking for the management of reactive nitrogen flows in wastewater systems based on system dynamics. Six scenarios were simulated for nitrogen flows in wastewater systems and related components.
Subject(s)
Decision Support Systems, Management , Fertilizers/analysis , Models, Theoretical , Nitrogen/analysis , Waste Disposal, Fluid/methods , Wastewater/chemistry , Fertilizers/economics , Waste Disposal, Fluid/economicsABSTRACT
RESUMO Os encargos energéticos decorrentes do Sistema Integrado de Abastecimento de Água de Feira de Santana (SIAA-FSA) foram analisados utilizando o método de avaliação do ciclo de vida. Foram identificadas, na cadeia de abastecimento de água, as etapas do sistema com maiores encargos energéticos, e propostos cenários de melhoria. Cadeias de produção dos insumos químicos, transporte dos insumos, energia elétrica e substituição dos tubos na rede para a manutenção do SIAA-FSA foram consideradas. A demanda energética acumulada do SIAA-FSA foi de 3,51 kWh.m-3 de água consumida. As etapas de captação e distribuição de água apresentaram os maiores consumos energéticos, e a eletricidade do bombeamento representou 86% da demanda energética acumulada. Os cenários propostos para o SIAA-FSA apresentaram melhorias significativas em relação ao cenário atual, com usos mais racionais de insumos químicos, eletricidade e água.
ABSTRACT The energy burdens of the Feira de Santana Integrated Water Supply System (SIAA-FSA) were analyzed using the life cycle assessment method. The higher energy burdens in the water supply chain were identified and scenarios for improvement were proposed. The supply chain of chemicals, transportation, electricity and replacement of pipes were considered for SIAA-FSA. The cumulative energy demand of SIAA-FSA was 3.51 kWh.m-3 of consumed water. The water uptake and distribution steps presented the highest energy demands, and the electricity for pumping represented 86% of the cumulative energy demand. The SIAA-FSA proposed scenarios showed significant improvements over the current one, with rational use of chemicals, electricity and water.
