Study of Fuel Properties of Torrefied Municipal Solid Waste

Incineration is one of the major methods for processing municipal solid waste (MSW) harmlessly; however, it could lead to low combustion efficiency and secondary pollution problems because of the high moisture content and low energy density of MSW. Torrefaction has been reported to be effective in removing moisture and improving combustion properties in various materials, such as feedstock and wood. The aim of this study was to investigate whether torrefaction could be used as a practical pretreatment method by improving the combustion properties and reducing the chloride content of MSW. Typical combustible components in MSW were chosen and torrefied at various temperatures (250, 300, 350, 400, and 450 degrees C), under a N-2 atmosphere for 30 min. The calorific values of MSW became higher after torrefaction between 250 and 350 degrees C. At a torrefaction temperature of 300 degrees C, the torrefied MSW sample produced similar calorific values to those of standard coal. Under this condition, the chlorine content of the torrefied MSW sample was 57% lower than non-torrefied samples. In addition, the grindability of the torrefied sample was better than that of synthetic MSW. The improved grindability, lower chlorine content, higher heat value, and superior combustion characteristics of torrefied MSW suggested that torrefaction may be used as an effective MSW pretreatment, and the torrefied MSW is more suitable to be used as fuel than non-torrefied MSW

Meta-analysis of environmental contamination by alkylphenols.

International audienceAlkylphenols and alkylphenol ethoxylates (APE) are toxics classified as endocrine-disrupting compounds; they are used in detergents, paints, herbicides, pesticides, emulsifiers, wetting and dispersing agents, antistatic agents, demulsifiers, and solubilizers. Many studies have reported the occurrence of alkylphenols in different environmental matrices, though none of these studies have yet to establish a comprehensive overview of such compounds in the water cycle within an urban environment. This review summarizes APE concentrations for all environmental media throughout the water cycle, from the atmosphere to receiving waters. Once the occurrence of compounds has been assessed for each environmental compartment (urban wastewater, wastewater treatment plants [WWTP], atmosphere, and the natural environment), data are examined in order to understand the fate of APE in the environment and establish their geographical and historical trends. From this database, it is clear that the environment in Europe is much more contaminated by APE compared to North America and developing countries, although these APE levels have been decreasing in the last decade. APE concentrations in the WWTP effluent of developed countries have decreased by a factor of 100 over the past 30 years. This study is aimed at identifying both the correlations existing between environmental compartments and the processes that influence the fate and transport of these contaminants in the environment. In industrial countries, the concentrations observed in waterways now represent the background level of contamination, which provides evidence of a past diffuse pollution in these countries, whereas sediment analyses conducted in developing countries show an increase in APE content over the last several years. Finally, similar trends have been observed in samples drawn from Europe and North America