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Gasification of wastes is considered a promising alternative for energy generation due to its lower environmental impacts when compared with conventional landfilling and incineration. Valorisation of such wastes improves sustainability of resource management and of energy production. However, an appropriate characterisation of wastes in terms of physical and chemical properties is essential for the prediction of their behaviour during gasification, allowing to identify possible problems for the environment and installed equipment and also to define which materials present a greater energy potential. This study aimed to characterise 10 different fractions from municipal, construction and demolition wastes received in different fluxes by a Portuguese waste management company. These fractions included wood (44.83 wt%), plastic (22.15 wt%), paper/card (0.04 wt%), mixtures of paper and plastic (14.67 wt%) and sewage sludge (18.31 wt%). For this purpose, determination of density, proximate and ultimate analysis, higher heating value (HHV), thermogravimetric profiles and inorganic composition of ashes were performed for each fraction. Analysis revealed that plastics and their mixtures with paper/card possess the highest HHV's (25-45 MJ/kg db), thus exhibiting a greater capacity for energy production. High levels of ashes found in dried sewage sludge (50 wt % db) indicate that a lot of by-product will be generated after gasification, possibly increasing the treatment costs. A gasification unit operating at 50 kg/h and admitting a mixture of all these wastes would generate 109.7 kW of total power, having capacity to receive more waste fluxes along the year.

Abstract:Textile industries have as main characteristic the generation of effluents with high color, and efficient treatment techniques are necessary. In this context, this study compared the efficiency of the electrochemical treatment for color removal from synthetic textile effluent using two configurations of sacrificial electrodes, parallel plates and array of cylindrical electrodes. For application of the electroflocculation technique, an electrochemical reactor was used, in a laboratory scale, operated in a continuous flow. The synthetic textile effluent was prepared with preset concentrations of reactive dye Blue 5G and sodium chloride. Sacrificial iron (Fe) electrodes with different configurations were used: parallel plates and cylindrical electrodes. The Hydraulic Retention Time (HRT) and electric current density (j) were controlled, and their effects on color removal were evaluated using a Central Composite Rotational Design (CCRD) composed of 12 trials. For the electrochemical treatment using parallel plates, the color removal efficiency ranged from 56.13% to 98.95% and for the electrochemical treatment using an array of cylindrical electrode, the color removal efficiency varied from 2.11% to 97.84%. The mathematical models representative of the process explained a high proportion of the total data variability, with a coefficient of variation of 99.49% and 97.21% for parallel plates and arrangement of cylindrical electrodes, respectively. The electrochemical treatment using parallel plates presents advantages over the configuration using a cylindrical electrode array, since the color removal efficiency is superior under the same operating conditions, representing economic and environmental gains.Keywords: Dyes. Cylindrical electrodes. Electroflocculation. Mathematical modeling. Parallel plates.Resumo: Indústrias têxteis possuem como principal característica a geração de efluentes com elevada coloração, sendo necessárias técnicas eficientes de tratamento. Neste contexto, o presente artigo tem como objetivo comparar a eficiência do tratamento eletroquímico para a remoção de cor de efluente têxtil sintético utilizando duas configurações de eletrodos de sacrifício, placas paralelas e arranjo de eletrodos cilíndricos. Para a aplicação da técnica de eletrofloculação, utilizou-se um reator eletroquímico, em escala laboratorial, operado em fluxo contínuo. O efluente têxtil sintético foi preparado com concentrações preestabelecidas de corante reativo azul 5G e cloreto de sódio. Utilizou-se eletrodos de sacrifício de ferro (Fe) com diferentes configurações: placas paralelas e eletrodos cilíndricos. Foram controlados os fatores Tempo de Retenção Hidráulica (TRH) e densidade de corrente elétrica (j), sendo seus efeitos sobre a remoção de cor avaliados utilizando-se um delineamento composto central rotacional (DCCR) composto por 12 ensaios. Para o tratamento eletroquímico utilizando placas paralelas a eficiência de remoção da cor variou de 56,13% a 98,95% e para o tratamento eletroquímico utilizando arranjo de ele...

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