Evaluation of the dioxin and furan formation thermodynamics in combustion processes of urban solid wastes

Specific combustion programs (Gaseq, Chemical equilibria in perfect gases, Chris Morley) are used to model dioxin and formation in the incineration processes of urban solid wastes. Thanks to these programs, it is possible to establish correlations with the formation mechanisms postulated in literature on the subject. It was found that minimum oxygen quantities are required to obtain a significant formation of these compounds and that more furans than dioxins are formed. Likewise, dioxin and furan formation is related to the presence of carbon monoxide, and dioxin and furan distribution among its different compounds depends on the chlorine and hydrogen relative composition. This is due to the fact that an increased chlorine availability leads to the formation of compounds bearing a higher chlorine concentration (penta-, hexa-, hepta-, and octachlorides), whereas an increased hydrogen availability leads to the formation of compounds bearing a lower chlorine number (mono, di-, tri-, and tetrachlorides).

Comparison of the methane oxidation rate in four media

Landfill gas emissions are one of the main sources of anthropogenic methane (CH4), a major greenhouse gas. In this paper, an economically attractive alternative to minimize greenhouse gas emissions from municipal solid waste landfills was sought. This alternative consists in special biofilters as landfill covers with oxidative capacity in the presence of CH4. To improve the quality/cost ratio of the project, compost was chosen as one of the cover substrates and soil (Typic red yellow-silt-clay Podzolic) as the other. The performance of four substrates was studied in laboratory experiments: municipal solid waste (MSW) compost, soil, and two soil-compost at different proportions. This study aimed to evaluate the suitability and environmental compatibility as a means of CH4 oxidation in biofilters. Four biofilters were constructed in 60 cm PVC tubes with an internal diameter of 10 cm. Each filter contained 2.3 L of oxidizing substrate at the beginning of the experiment. The gas used was a mixture of CH4 and air introduced at the bottom of each biofilter, at a flow of 150 mL min-1, by a flow meter. One hundred days after the beginning of the experiment, the best biofilter was the MSW compost with an oxidation rate of 990 g m-3 day-1 , corresponding to an efficiency of 44 %. It can be concluded that the four substrates studied have satisfactory oxidative capacity, and the substrates can be used advantageously as cover substrate of MSW landfills.

Recuperação de metais de catalisadores de hidrorrefino usados via fusão com KHSO4

This work describes a process for metal recovery from spent NiMo and CoMo/Al2O3 commercial hydrorefining catalysts. The samples were treated by fusion with potassium hydrogen sulfate (5 h, 600 ºC) with a KHSO4/catalyst mass ratio of 10:1. After fusion the solid was solubilized in water (100 ºC), leaving silicon compounds as residue. Losses of nickel and cobalt may reach 16 wt% of the amount present in the sample, depending on the silicon content. Soluble metals were isolated by selective precipitation techniques (nickel, cobalt, aluminum) or by solvent extraction with methyl-isobutyl ketone (molybdenum) in a hydrochloric acid medium. All metals were recovered in very good yields except for nickel and cobalt in the presence of considerable amounts of silicon. Soluble wastes consist of potassium/sodium sulfates/chlorides. Solid wastes correspond to about 4 wt% of the catalyst and can be discarded in industrial dumps.

Extração sequencial de zinco e cobre em solos tratados com lodo de esgoto e composto de lixo

This work aimed to access the contents and chemical forms and to estimate mobility and availability of cooper and zinc in samples from two soils (Haplortox and Paleudult) previously treated with doses of sewage sludge (SS) and municipal solid waste compost (MSWC), besides a control treatment. Largest percentages of Cu and Zn were determined in the organic matter fraction. Zn showed higher percentages of soluble and exchangeable fractions than Cu. Treatments with SS showed higher potential of Cu and Zn availability. Modifications in soil attributes due to residue application affected metal mobility and availability indexes.

Reciclagem do lixo de informática: uma oportunidade para a química

Recycling and sustainable development are increasing in importance around the world. In Brazil, the new National Policy on Solid Wastes has prompted discussion on the future of electronic waste (e-waste). Brazil generates the greatest amount of e-waste among Latin American countries. Nevertheless complete recycling, including end processing of e-waste, does not occur in Brazil. This paper discusses the physical and chemical technologies currently used worldwide and in Brazil for printed circuit board recycling, with emphasis on metal recovery and plastic processing. The goal is to put in evidence the important role that chemistry can play in developing cheaper processes to recycle e-waste.

Industrial and urban organic wastes increase soil microbial activity and biomass

Microbial processes have been used as indicators of soil quality, due to the high sensitivity to small changes in management to evaluate, e.g., the impact of applying organic residues to the soil. In an experiment in a completely randomized factorial design 6 x 13 + 4, (pot without soil and residue or absolute control) the effect of following organic wastes was evaluated: pulp mill sludge, petrochemical complex sludge, municipal sewage sludge, dairy factory sewage sludge, waste from pulp industry and control (soil without organic waste) after 2, 4, 6, 12, 14, 20, 28, 36, 44, 60, 74, 86, and 98 days of incubation on some soil microbial properties, with four replications. The soil microbial activity was highly sensitive to the carbon/nitrogen ratio of the organic wastes. The amount of mineralized carbon was proportional to the quantity of soil-applied carbon. The average carbon dioxide emanating from the soil with pulp mill sludge, corresponding to soil basal respiration, was 0.141 mg C-CO2 100 g-1 soil h-1. This value is 6.4 times higher than in the control, resulting in a significant increase in the metabolic quotient from 0.005 in the control to 0.025 mg C-CO2 g-1 Cmic h-1 in the soil with pulp mill sludge. The metabolic quotient in the other treatments did not differ from the control (p < 0.01), demonstrating that these organic wastes cause no disturbance in the microbial community.

Production of fungal protein by solid substrate fermentation of cactus Cereus peruvianus and Opuntia ficus indica

Agricultural wastes from cactus Cereus peruvianus and Opuntia ficus indica were investigated for protein production by solid substrate fermentation. Firstly, the polyelectrolytes were extracted and used in water cleaning as auxiliary of flocculation and coagulation. The remaining fibrous material and peels were used as substrate for fermentation with Aspergillus niger. Glucoamylase and cellulase were the main enzymes produced. Amino acids were determined by HPLC and protein by Lowry's method. After 120 hours of fermentation the protein increased by 12.8%. Aspartic acid (1.27%), threonine (0.97%), glutamic acid (0.88%), valine (0.70%), serine (0.68%), arginine (0.82%), and phenylalanine (0.51%) were the principal amino acids produced.

A tecnologia da reciclagem de polímeros

Solid municipal waste contains a large volume of polymers and its final disposal is a serious environmental problem. Consequently, the recycling of the principal polymers present in the solid waste is an alternative. In this review we describe the mechanical and chemical recycling of polymers and the energy recovery from plastic wastes. Polymer recycling involves not only the development of processing technologies, but also the solution of many chemical and analytical problems. The technological, economical and social aspects of polymer recycling are also considered.

Decolorization and toxicity of municipal waste by horseradish (Cochlearia armoracia)

The Municipal Station of Americana, SP, Brazil, treats a volume of 400 l s-1 of effluent, of domestic and textile origin, and produces about 20 t of sludge per day. The plant horseradish, which contains high amount of peroxidases, was able to decolorize this effluent in 2 h and the solid waste in 2 days, at concentrations of 10 and 50%, respectively. However, there was an increase in the toxicity for the bioassays with Hydra attenuatta, Selenastrum capricornutum and lettuce seeds, indicating formation of more toxic substances. Since horseradish showed the ability to decolorize these residues, it can be used as pre-treatment resulting in a sludge of less complex composition.

Reforma administrativa nos anos 90: o caso da prefeitura municipal de São Paulo

A partir de um retrospecto histórico dos processos de reforma administrativa no Brasil, o estudo destaca os desafios colocados para as intervenções de mudança na esfera pública nos dias atuais, tanto de nível organizacional (eficácia e eficiência), quanto social (participação e democracia). É apresentado o caso da Prefeitura Municipal de São Paulo, com base no modelo organizacional atual, colocandose, a seguir, a proposta de reforma. Sua análise é baseada no referencial histórico construído anteriormente. A proposição de reforma apresentada contribui com soluções inovadoras e criativas para velhos problemas da gestão pública.

Plano diretor e planejamento estratégico municipal: introdução teórico-conceitual

Este artigo discute de forma teórico-conceitual o plano diretor municipal e o planejamento estratégico municipal, instrumentos de planejamento em uso atualmente, que constituem o que se pode chamar de utopias contemporâneas para a questão urbana brasileira. Preliminarmente, contextualizando cada um deles num cenário maior de políticas urbanas. A discussão é fruto de estudos de casos que contaram com a participação dos autores. O plano diretor, mais comumente entendido pela urbanística contemporânea e pela política urbana brasileira, é contextualizado por meio das suas alterações conceituais e processuais após o estabelecimento das diretrizes do Estatuto da Cidade. Já o planejamento estratégico é abordado numa visão atual da administração pública, ainda compromissada com os interesses da maioria da população, mas igualmente obrigando-se a adotar práticas de efetividade até então restritas ao setor privado. Ressalta-se na conclusão que tais instrumentos ora são valorizados, ora esquecidos na prática urbana nacional.

Modelo de gestão municipal baseado na utilização estratégica de recursos da tecnologia da informação para a gestão governamental: formatação do modelo e avaliação em um município

São desafios constantes da gestão efetiva dos municípios a estruturação e disponibilização de informações confiáveis, oportunas e personalizadas para apoiar as decisões da administração pública municipal e para elaborar e controlar o planejamento estratégico municipal alinhado aos anseios dos cidadãos. A adaptação de modelos de gestão da iniciativa privada para o ambiente público é uma alternativa para enfrentar esses desafios. Este artigo propõe e avalia um modelo para a gestão governamental. O modelo é baseado na utilização estratégica da tecnologia da informação, que proporcione ao gestor público monitoração e controle da execução estratégica, informações executivas para a tomada de decisão, gestão dos relacionamentos com os cidadãos e o domínio sobre os processos da gestão municipal. A metodologia da pesquisa enfatizou o estudo de caso no município de Curitiba, utilizando um protocolo de pesquisa elaborado a partir da pesquisa bibliográfica exploratória. A seguir, são analisados diferenças, similaridades e resultados da aplicação de elementos que compõem o modelo proposto no município estudado. A conclusão evidencia que a utilização e adaptação do modelo proposto nas gestões municipais podem contribuir significativamente na evolução de seus modelos de gestão.

Construção e validação de medida para diagnóstico de competências relativas às funções de prefeito(a) e secretário(a) municipal

A gestão por competências tem merecido crescente atenção por parte de profissionais e acadêmicos desde seu surgimento. Sobre o setor público, percebe-se uma lacuna no que diz respeito a estudos teóricos ou empíricos que se refiram aos níveis estadual e municipal, e, do mesmo modo, no que se refere a seu primeiro escalão. O presente artigo relata a construção de um instrumento de medida para diagnóstico de competências de prefeitos(as) e secretários(as) municipais, realizada por meio de entrevistas com 17 pessoas exercendo o mandato, e sua validação com uma amostra de 455 outros sujeitos iniciando e concluindo mandatos. Os indicadores obtidos na análise fatorial sugerem a validade psicométrica do instrumento e a estrutura empírica está consistente com a teoria sobre competências.