Multi-production of solid fuel and liquid fertilizer from organic waste by employing wet torrefaction process

Preliminary survey showed that organic waste from the market is about 18.77%, or second largest in the total waste generation. Its management becomes a challenge, because it is not comprised only of organics but also mixed with small amount of plastics; therefore, conventional biological process will not achieve their maximum efficiency. Wet torrefaction is a thermal process in hot water medium, which will dissolve organic materials into water, effectively converting most solids into liquid product. Banana fruit stem and cabbage were chosen as the mixed organic waste representative, and treated in a 2.5 L reactor using saturated steam in the temperature range of 175 to 225 °C before being analyzed for their heating value in solid products as fuel precursors, and their nitrogen, phosphorus and potassium (NPK) contents in liquid products as liquid fertilizer precursors. It was found that for cabbage, the wet torrefaction process at 200 °C and 90 min resulted in 15.59 MJ/kg product heating value with NPK content of 3.43%. For banana fruit bunch stem, the wet torrefaction process at 225 °C and 30 min resulted in 17.64 MJ/kg product heating value with NPK content of 5.13%. It can be concluded that wet torrefaction process can simultaneously produce solid and liquid product as solid fuel and liquid fertilizer, respectively.Preliminary survey showed that organic waste from the market is about 18.77%, or second largest in the total waste generation. Its management becomes a challenge, because it is not comprised only of organics but also mixed with small amount of plastics; therefore, conventional biological process will not achieve their maximum efficiency. Wet torrefaction is a thermal process in hot water medium, which will dissolve organic materials into water, effectively converting most solids into liquid product. Banana fruit stem and cabbage were chosen as the mixed organic waste representative, and treated in a 2.5 L reactor using saturated steam in the temperature range of 175 to 225 °C before being analyzed for their heating value in solid products as fuel precursors, and their nitrogen, phosphorus and potassium (NPK) contents in liquid products as liquid fertilizer precursors. It was found that for cabbage, the wet torrefaction process at 200 °C and 90 min resulted in 15.59 MJ/kg product heating value with NPK con...