Energetic performances and environmental impact of the combustion of cardboard/sawdust in a domestic boiler

• Pelletization of cardboard wastes.
• Determination of thermal properties in view of their energy recovery.
• Combustion tests in domestic pellets boiler.
• Determination of boiler and combustion efficiencies.
• Measurements of main gaseous and particulate pollutants.

The French Grenelle environment initiative defined different actions for sustainable development. One of them was to recycle 75% of the household packaging in 2012. Nowadays 4400 million tons are recycled representing 86% the total of papers and cardboard packaging. This paper studies the energy recovery of paper and cardboard pellets, pure or blended with sawdust in a commercial residential pellet boiler. Wood pellets complying with the standard DIN CERTCO are used as reference material to compare combustion behavior and emissions. Physicochemical characteristics such as ultimate and proximate analyses and calorific values were determined. The four pellet-types were combusted in a domestic pellets boiler according to European EN 303-5 standard. Main gaseous pollutants and particulate matter were analyzed. With low heating values of the cardboard pellets close to 14 MJ kg−1, their combustion did not have significant environmental impact. Emissions of CO and particulate matter were below the values required by the European standard NF EN 303-5 and the French label Flamme Verte. Despite the high ash content close to 7.7% (dry basis) in the case of 100% cardboard pellets, their combustion did not generate notably more particulate matter than wood pellets. Residual ashes will be analyzed to consider their potential use.