Livestock Manure Compost Mixed with Biochar: Efficient Pelleting and Pellet Production Characteristics

Abstract Biochar is difficult to make pellets on its own. The pelleting of biochar mixed with livestock manure compost could have the following advantages: (1) use compost as a binder, (2) reduce the moisture content of compost for pelleting by simply mixing without drying, and (3) promote the application of biochar for carbon sequestration by simultaneous application with agricultural machinery for chemical fertilizers while preventing dust pollution and additional work for the farmer. Fertilizer pellets need to be produced in an economical manner. Therefore, we empirically examined the productivity of pelleting using a roller die pellet mill, which is characterized by high throughput and is commonly used in the mass production of multifertilizer and wood pellets. Although a feedstock with 25% biochar mixed with cattle manure compost produced fewer pellets than a feedstock consisting of only compost, the energy input per unit of production remained the same. The results suggest that the addition of biochar may not increase GHG emissions during the production of this new material. Durability and wettability showed similar or higher values in the mixed pellets, indicating that the new material can be used as a fertilizer in the same way as cattle manure pellets.