Combustion behaviour of different types of solid wastes and their blends with lignite

The combustion characteristics of blends of lignite with various organic waste materials are evaluated in this study in order to assess their potential for energy recovery. Different types of municipal solid waste (i. e. paper, plastic, textile, organic), as well as sewage sludge and agri-residues (sunflower shells) samples were collected from the Western Macedonia region, northern Greece. Mixtures of each one of them with lignite in different proportions (30-50-70 wt.%) were prepared. Proximate analysis, calorific value determination, and thermogravimetry (TGA/ DTG) were performed. Thermal parameters such as ignition temperature, total weight loss, maximum rate of weight loss, peak and burnout temperatures and burnout time were determined from the TG/DTG profiles of the raw materials and their blends. The combined utilization of proximate analysis, calorific value determination and TG/DTG method proved to be an effective method for a preliminary assessment of the energetic potential of raw solid waste “combustible” materials and their blends with lignite. The analytical results revealed that most of the blends are promising for energy recovery. Regarding the raw wastes, sunflower shells were the most reactive. A non-synergistic effect was found for the blends. Organic and sewage sludge blends revealed the lowest combustibility, which is attributed to the high content of inorganic matter and the heterogeneity of these two types of wastes.