Abstract: There is a huge amount of organic solid waste resources such as kitchen waste anaerobic fermentation biogas residue and garden waste in China. Pyrolysis carbonization is an effective way to recycle organic solid waste. The yield, physical and chemical properties and structural characterization of pyrolysis biomass char from different biomass raw materials still need to be systematically studied. The kitchen waste anaerobic fermentation biogas residue and garden waste were used as raw materials, the physical and chemical properties such as nutrient content, microstructure, functional groups, and structural characteristics of two kinds of solid waste pyrolysis biochar were analyzed. The biogas residue biochar yield and garden waste biochar yield were 62.7% and 70.1%, respectively. The pH values were 9.61 and 10.01, and the electrical conductivity were 1.25, 0.55 mS/cm, respectively. The total nutrient content were 6.26% and 4.63%, and the fixed carbon content were 54.80% and 67.90%, respectively. The specific surface area of biogas residue biochar was basically the same as that of garden waste biochar（with values of 7.73, 8.03 m2/g, respectively）, and pore volumes of 0.025, 0.011 cm3/g, with pore sizes of 10.14, 4.70 nm, respectively. There were significant differences in the types of functional groups between the two types of biochar, with biogas residue biochar had more functional groups than garden waste biochar, but the crystal structures of the two were basically the same. Both biogas residue and garden waste could be used to produce biochar-based fertilizers, but the nutrient content and pore structure of biogas residue biochar were better than those of garden waste biochar, which could be used to improve soil comprehensive fertility. The organic carbon content of garden waste biochar was higher, which was beneficial for increasing soil carbon sink.

Key words: biogas residue of kitchen waste, garden waste, pyrolysis carbonization, biochar, structural characterization