A study on the drying characteristics from mixture of food waste and sawdust by using microwave/inner-cycle thermal-air drying process

The main objective of this study is a development for recycling food waste by using the microwave/inner-cycle thermal-air drying process. And this research is also aiming to assess the quality of refuse-derived fuel (RDF) based on operating parameters such as different mixture ratios, the amounts of food waste (70–100 %) and sawdust (0–30 %). For homogeneous mixture of the food waste with combustible materials and better drying efficiency, foreign substances were removed. Also, to improve the drying efficiency and heating values of the food waste, experiments were carried out to dry a mixture of powder-type sawdust which is resized <2 mm of diameter. The microwave intensity and thermal air temperature were controlled 1 kW and 200 °C, respectively. The mixture of the food waste with sawdust (70:30) was dried using the microwave–thermal air (1 kW, 200 °C). The drying process led to the final moisture content of 5.8 %, which was the lowest level (required <10 %) with 10 min operating period. In this moisture content, lower heating value for the RDF was 5,660 kcal/kg. The food waste mixed with the waste sawdust was found to produce good-quality RDF that met the quality standard across all mixture ratios.