Apoio à atualização da metodologia de quantificação e caracterização física dos resíduos urbanos em Portugal
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2024
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obtenção de dados fiáveis sobre a composição e a quantificação dos resíduos urbanos é essencial para o seu sistema de gestão, uma vez que define todos os parâmetros que são eficazes no processo de tomada de decisão. O objetivo deste trabalho é apoiar a atualização da metodologia portuguesa de caracterização e quantificação de resíduos urbanos, aprovada pela Portaria n.º 851/2009, que já se encontra em curso. Para o efeito, foram compilados 25 artigos científicos, abrangendo metodologias aplicadas em 10 países europeus e 15 países não europeus, além de 5 metodologias nacionais de países europeus, de forma a identificar os melhores procedimentos adotados nos últimos 15 anos. Os resultados mostraram que os países europeus têm vindo a desenvolver a sua própria metodologia com base noutras de referência, procurando enriquecer a metodologia lançada pela Comissão Europeia em 2004, numa tentativa de a uniformizar, enquanto nos países não europeus a metodologia americana D 5231-92 tem sido a mais utilizada. Os fatores-chave na aplicação desta metodologia foram a estratificação, a amostragem, a classificação das categorias e as análises estatísticas. No que diz respeito à estratificação, o tipo de amostragem aleatória estratificada foi considerado o mais representativo. 9 dos 10 artigos científicos de países europeus tiveram como alvo do estudo os resíduos domésticos, tal como as 5 metodologias nacionais. No que se refere à amostragem, o nível predominante nos países não europeus foi por veículo de recolha, enquanto nos países europeus foi por habitação. A unidade e a quantidade da amostra variaram consideravelmente entre todos os estudos compilados. Em geral, a duração das campanhas foi de 1 semana, variando o número de campanhas anuais. Quanto à preparação da amostra, os países não europeus utilizaram mais o método de cone e quarteio, enquanto os países europeus utilizaram mais o método de pilha plana e alongada ou não reduziram a amostra para evitar os erros da Teoria da Amostragem (TAM). Em relação à classificação das categorias, a triagem manual foi realizada em todos os estudos, com procedimentos diferentes e categorias; o catálogo de triagem vem sendo desenvolvido em 3 níveis nos países europeus, conhecido como “abordagem hierárquica das frações de resíduos”. As análises estatísticas estão a evoluir nos países europeus para análises de dados composicionais (CoDa), isto é, análises estatísticas mais robustas que respeitam a distribuição não normal dos dados e a sua restrição de soma constante. Concluiu-se que a falta de uma metodologia uniformizada impossibilita a comparação entre diferentes estudos. No que corresponde à estratificação, a metodologia portuguesa deve ter os resíduos domésticos como alvo do estudo, deve ser escolhido o tipo de amostragem aleatória estratificada, com pelo menos 5 estratos, e devem ser identificados os fatores específicos que influenciam a composição e quantificação dos resíduos urbanos em cada região. Relativamente à amostragem, o nível sugerido é por veículo de recolha em cada estrato e sem compactação da amostra, sendo a amostra inicial reduzida em 5 subamostras de 100 kg, através do método de pilha plana e alongada, totalizando 25 subamostras por campanha, com a duração de 1 semana completa. Nesta fase, devem ser tidos em conta os resíduos volumosos, a contaminação e o teor de humidade dos resíduos. O catálogo de triagem deve ser desenvolvido em 3 níveis: nível I para o tipo de material, nível II para a finalidade dos resíduos e nível III para as necessidades das entidades gestoras, e os resíduos finos devem ser separados com base na observação visual e em diferentes categorias sem os peneirar. No que tange às análises estatísticas, é necessário realizar transformações logarítmicas isométricas dos dados, priorizar medidas de tendência central e de variabilidade que melhor representem dados com uma distribuição não normal, utilizando testes estatísticos não paramétricos. Por fim, a quantidade de membros da equipa de caracterização deve ser testada e, sobretudo, devem ser envidados todos os esforços para garantir a sua saúde e segurança. Palavras-chaves: resíduos urbanos; caracterização física; estratificação; triagem manual; análises estatísticas.
Obtaining reliable data on the composition and quantification of municipal waste is essential for its management system, as it defines all the parameters that are effective in the decision-making process. The aim of this work is to support the updating of the Portuguese methodology for characterising and quantifying municipal waste, approved by Ministerial Order 851/2009, which is already underway. To this end, 25 scientific articles were compiled, covering methodologies applied in 10 European countries and 15 non-European countries, as well as 5 national methodologies from European countries, in order to identify the best procedures adopted over the last 15 years. The results showed that European countries have been developing their own methodology based on reference ones, seeking to enrich the methodology launched by the European Commission in 2004 in an attempt to standardise it, while in non-European countries the American D 5231-92 methodology has been the most widely used. The key factors in applying this methodology were stratification, sampling, classification of categories and statistical analyses. With regard to stratification, stratified random sampling was considered the most representative. 9 of the 10 scientific articles from European countries targeted household waste, as did the 5 national methodologies. With regard to sampling, the predominant level in non-European countries was by collection vehicle, while in European countries it was by dwelling. The unit and quantity of the sample varied considerably between all the studies compiled. In general, the duration of the campaigns was 1 week, with the number of annual campaigns varying. As for sample preparation, the non-European countries used the cone and block method more, while the European countries used the flat and elongated pile method more or did not reduce the sample to avoid sampling theory (TAM) errors. Regarding the classification of categories, manual sorting was carried out in all the studies, with different procedures and categories; the sorting catalogue has been developed on 3 levels in European countries, known as the "hierarchical approach to waste fractions". Statistical analyses are evolving in European countries towards compositional data analyses (CoDa), i.e., more robust statistical analyses that respect the non-normal distribution of the data and its constant sum constraint. It was concluded that the lack of a standardised methodology makes it impossible to compare different studies. With regard to stratification, the Portuguese methodology should have household waste as the target of the study, the type of stratified random sampling should be chosen, with at least 5 strata, and the specific factors that influence the composition and quantification of municipal waste in each region should be identified. With regard to sampling, the suggested level is by collection vehicle in each stratum and without compacting the sample, with the initial sample being reduced into 6 subsamples of 100 kg, using the flat and elongated pile method, totalling 30 subsamples per campaign, lasting 1 full week. At this stage, bulky waste, contamination and the moisture content of the waste must be taken into account. The sorting catalogue should be developed on 3 levels: level I for the type of material, level II for the purpose of the waste and level III for the needs of the managing bodies, and fine waste should be separated on the basis of visual observation and into different categories without sieving. As far as statistical analyses are concerned, it is necessary to carry out isometric logarithmic transformations of the data, prioritise measures of central tendency and variability that best represent data with a non-normal distribution, using non-parametric statistical tests. Finally, the number of members of the characterisation team should be tested and, above all, every effort should be made to ensure their health and safety. Keywords: municipal waste; physical characterisation; stratification; manual sorting; statistical analysis.
Obtaining reliable data on the composition and quantification of municipal waste is essential for its management system, as it defines all the parameters that are effective in the decision-making process. The aim of this work is to support the updating of the Portuguese methodology for characterising and quantifying municipal waste, approved by Ministerial Order 851/2009, which is already underway. To this end, 25 scientific articles were compiled, covering methodologies applied in 10 European countries and 15 non-European countries, as well as 5 national methodologies from European countries, in order to identify the best procedures adopted over the last 15 years. The results showed that European countries have been developing their own methodology based on reference ones, seeking to enrich the methodology launched by the European Commission in 2004 in an attempt to standardise it, while in non-European countries the American D 5231-92 methodology has been the most widely used. The key factors in applying this methodology were stratification, sampling, classification of categories and statistical analyses. With regard to stratification, stratified random sampling was considered the most representative. 9 of the 10 scientific articles from European countries targeted household waste, as did the 5 national methodologies. With regard to sampling, the predominant level in non-European countries was by collection vehicle, while in European countries it was by dwelling. The unit and quantity of the sample varied considerably between all the studies compiled. In general, the duration of the campaigns was 1 week, with the number of annual campaigns varying. As for sample preparation, the non-European countries used the cone and block method more, while the European countries used the flat and elongated pile method more or did not reduce the sample to avoid sampling theory (TAM) errors. Regarding the classification of categories, manual sorting was carried out in all the studies, with different procedures and categories; the sorting catalogue has been developed on 3 levels in European countries, known as the "hierarchical approach to waste fractions". Statistical analyses are evolving in European countries towards compositional data analyses (CoDa), i.e., more robust statistical analyses that respect the non-normal distribution of the data and its constant sum constraint. It was concluded that the lack of a standardised methodology makes it impossible to compare different studies. With regard to stratification, the Portuguese methodology should have household waste as the target of the study, the type of stratified random sampling should be chosen, with at least 5 strata, and the specific factors that influence the composition and quantification of municipal waste in each region should be identified. With regard to sampling, the suggested level is by collection vehicle in each stratum and without compacting the sample, with the initial sample being reduced into 6 subsamples of 100 kg, using the flat and elongated pile method, totalling 30 subsamples per campaign, lasting 1 full week. At this stage, bulky waste, contamination and the moisture content of the waste must be taken into account. The sorting catalogue should be developed on 3 levels: level I for the type of material, level II for the purpose of the waste and level III for the needs of the managing bodies, and fine waste should be separated on the basis of visual observation and into different categories without sieving. As far as statistical analyses are concerned, it is necessary to carry out isometric logarithmic transformations of the data, prioritise measures of central tendency and variability that best represent data with a non-normal distribution, using non-parametric statistical tests. Finally, the number of members of the characterisation team should be tested and, above all, every effort should be made to ensure their health and safety. Keywords: municipal waste; physical characterisation; stratification; manual sorting; statistical analysis.
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ENVIRONMENTAL ENGINEERING, ENVIRONMENTAL SCIENCES, MUNICIPAL SOLID WASTE, STATISTICS, SAMPLING, WASTE MANAGEMENT, WASTE TREATMENT, MESTRADO EM ENGENHARIA DO AMBIENTE, ENGENHARIA DO AMBIENTE, CIÊNCIAS DO AMBIENTE, RESÍDUOS SÓLIDOS URBANOS, ESTATÍSTICA, AMOSTRAGEM, GESTÃO DE RESÍDUOS, TRATAMENTO DE RESÍDUOS, POLÍTICA PÚBLICA, Mestrado em Engenharia do Ambiente