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RESUMO Parte dos resíduos sólidos recicláveis gerada nas cidades é coletada por catadores. A atividade é considerada informal, mas reconhecida como a base da cadeia produtiva da reciclagem. Este artigo retrata uma investigação realizada com uma amostra de 29 catadores individuais em Esteio (RS), submetidos a entrevistas estruturadas. Os dados foram tratados estatisticamente e confrontados com dados de pesquisa pública disponível. Os resultados demonstraram que PET, alumínio, papel e papelão são os resíduos que mais atraem os catadores, que a média individual de coleta de recicláveis da amostra é cerca de 1.200 kg/mês e que as massas mínima e máxima de recicláveis para todos os catadores do município são, respectivamente, 102,5 e 257,3 t/mês. Esses resultados mostraram que o desempenho ambiental dos catadores é maior de 2,3 a 5,7 vezes quando comparado com o indicador da coleta seletiva formal de Esteio.
ABSTRACT Urban waste pickers collect part of the mass of recyclable solid waste in the cities. The activity has been considered informal, but it is recognized as the basis of the recycling's production chain. This paper discusses a research developed with 29 waste pickers in Esteio city, Brazil. The data were compared to the public research data available. The results indicated that PET, aluminum, paper and cardboard are the most economically attractive solid waste for the waste pickers. The data also indicated that the average individual recyclable materials collected by waste pickers is 1,200 kg/ month, and the minimum and maximum mass of recyclable materials for all municipality's waste pickers are respectively 102.5 and 257.3 t/month. These results showed that the environmental performance of waste pickers is from 2.3 to 5.7 times higher when the data are compared to the indicator of formal selective collection in Esteio city.
RESUMO
The extraction of sulphur produces a hematite-rich waste, known as roasted pyrite ash, which contains significant amounts of environmentally sensitive elements in variable concentrations and modes of occurrence. Whilst the mineralogy of roasted pyrite ash associated with iron or copper mining has been studied, as this is the main source of sulphur worldwide, the mineralogy, and more importantly, the characterization of submicron, ultrafine and nanoparticles, in coal-derived roasted pyrite ash remain to be resolved. In this work we provide essential data on the chemical composition and nanomineralogical assemblage of roasted pyrite ash. XRD, HR-TEM and FE-SEM were used to identify a large variety of minerals of anthropogenic origin. These phases result from highly complex chemical reactions occurring during the processing of coal pyrite of southern Brazil for sulphur extraction and further manufacture of sulphuric acid. Iron-rich submicron, ultrafine and nanoparticles within the ash may contain high proportions of toxic elements such as As, Se, U, among others. A number of elements, such as As, Cr, Cu, Co, La, Mn, Ni, Pb, Sb, Se, Sr, Ti, Zn, and Zr, were found to be present in individual nanoparticles and submicron, ultrafine and nanominerals (e.g. oxides, sulphates, clays) in concentrations of up to 5%. The study of nanominerals in roasted pyrite ash from coal rejects is important to develop an understanding on the nature of this by-product, and to assess the interaction between emitted nanominerals, ultra-fine particles, and atmospheric gases, rain or body fluids, and thus to evaluate the environmental and health impacts of pyrite ash materials.