Production of Alternative Fuels Based on Sewage Sludge

Abstract

Due to the growing demand for energy, conventional fossil fuels are being depleted. Reducing dependence on energy sources based on fossil fuels is possible by using the energy potential of biomass. Sewage sludge deserves special attention. The increase in the amount of sewage sludge produced around the world poses a serious problem with its management. The use of sewage sludge to produce fuel with the possibility of energy recovery seems to be an excellent solution. The article presents the results of laboratory tests on the production of fuel in the form of granulates from mixed sewage sludge, rubber waste, and wood waste in the form of sawdust. Fuel mixtures were tested, and fuel parameters were determined. The calorific value of the tested fuel ranged from 13.92 MJ/kg to 22.15 MJ/kg, and the moisture content from 41.57% to 18.36%, depending on the percentage composition of the mixtures used to produce the granules. The ash content ranged from 14.82% to 17.40%. The composition of granulated fuel mixtures has been designed to avoid additional drying or pre-drying of sewage sludge. In this way, fuel was obtained without additional energy consumption associated with drying sewage sludge. Moreover, it should be stated that the share of sewage sludge in granulated fuel should not exceed 25%. Nowadays, such fuel can be an alternative to fossil fuels used in the cement or energy industry.