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Sewage Sludge Disposal and Applications
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| Editorial: | INTECH -OPEN ACCESS PUBLISHER |
| Fecha de publicación: | 2010 |
| Idioma: | Ingles |
| Notas: | Municipal solid waste landfills often develop scenarios of self heating, causing negative environmental impacts by odors, gas generation and smoke production. Self-ignition and resulting fires at landfills have been undesirable outcomes in compost piles worldwide. Field, laboratory and numerical studies have been considered trying to reproduce and understand the conditions under which self-heating and combustion may take place. Inside a compost pile built from solids obtained after municipal wastewater treatment, oxygen, methane, carbon monoxide and carbon dioxide concentrations and temperature change with time and in depth. Electric conductivity and pH show only slight changes. In field piles temperature increased with time, reaching a maximum of about 90°C. While no spontaneous combustion was observed after six months in field experiments, in laboratory studies carried out in a closed bottom cylinder, self-ignition was observed and a maximum temperature of about 400°C was reached. Spontaneous combustion in compost piles is a chemical and biological process. Initially, the metabolism that allows microorganism growth causes temperature increase, but simultaneous oxidation of the organic matter also reinforces self-ignition at a lower value. When the temperature within the compost pile rises to about 87°C, self-ignition follows mainly due to cellulose oxidation. Therefore, the conditions under which biomass increases must be studied. An important factor in the development of internal changes within the compost pile comes from atmospheric boundary conditions. General convection, radiation, rain rate and atmospheric humidity must be included as boundary atmospheric field conditions on the lateral and top surfaces. |