Social metabolism and material flow analysis applied to waste management: A study case of Autonomous City of Buenos Aires, Argentina.

Waste Management in megacities is one of the most relevant issues around the world due to its environmental impacts and economic costs. In this work, we evaluate the application of the theoretical-methodological framework provided by Social Metabolism and Material Flow Analysis to analyze the Municipal Solid Waste Management in the Autonomous City of Buenos Aires (Argentina). The quantitative results evidence that 46% of the city's waste was disposed of in landfills outside its geographical limits, transferring environmental costs to the population on the outskirts of the city and other administrative jurisdictions. The city recycled the other 54% of the waste using different strategies like green centers for recyclable domestic waste (operated by 5500 registered Urban Recyclers/waste pickers recover), a Plant for treatment of pruning activities waste, a Plant for the treatment of construction and demolition waste, and a Mechanical-Biological Treatment Plant. Also in the city work, approximately 5000 informal waste pickers contributing to recycling waste. The approach shows the importance of the inclusion of waste pickers in the formal recycling system, and the failures of costly and inefficient large-scale technologies, as the Mechanical-Biological Treatment Plant. Also, the application of Social Metabolism and MFA allowed a characterization of the flows and processes that make up Municipal Solid Waste management in the area of study, despite the lack of systematized quantitative information. It facilitates a holistic visualization of waste management in the city for decision-makers.

Human urine fertiliser in the Brazilian semi-arid: Environmental assessment and water-energy-nutrient nexus.

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 1 ha of maize with 225 kg of nitrogen, 29 kg of phosphorus and 48 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 134 km (energy demand) and 84 km (environmental categories) by truck compared to 1841 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 193 km (energy demand) and 185 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.

Resource Use in Small Island States: Material Flows in Iceland and Trinidad and Tobago, 1961-2008.

Iceland and Trinidad and Tobago are small open, high-income island economies with very specific resource-use patterns. This article presents a material flow analysis (MFA) for the two countries covering a time period of nearly five decades. Both countries have a narrow domestic resource base, their economy being largely based on the exploitation of one or two key resources for export production. In the case of Trinidad and Tobago, the physical economy is dominated by oil and natural gas extraction and petrochemical industries, whereas Iceland's economy for centuries has been based on fisheries. More recently, abundant hydropower and geothermal heat were the basis for the establishment of large export-oriented metal processing industries, which fully depend on imported raw materials and make use of domestic renewable electricity. Both countries are highly dependent on these natural resources and vulnerable to overexploitation and price developments. We show how the export-oriented industries lead to high and growing levels of per capita material and energy use and carbon dioxide emissions resulting from large amounts of processing wastes and energy consumption in production processes. The example of small open economies with an industrial production system focused on few, but abundant, key resources and of comparatively low complexity provides interesting insights of how resource endowment paired with availability or absence of infrastructure and specific institutional arrangements drives domestic resource-use patterns. This also contributes to a better understanding and interpretation of MFA indicators, such as domestic material consumption.