Abstract:
The demand for biochar as a soil amendment is increasing due to its ability to enhance
soil properties and sequester carbon. While conventional biochar is known to improve soil
quality, it is not commonly recognized as a source of nutrients because the thermochemical
conversion process often results in the loss or leaching of the nutrients in the biochar
feedstock biomass. This research aimed at developing a novel method for manufacturing
nutrient enhanced biochar by pyrolyzing organic matter with inorganic matter. Here, a
combination of rice husk (RH) and fish waste (FW) were utilized as organic feedstocks,
while Eppawala Rock Phosphate (ERP) and Potassium Feldspar (PF) were employed as
inorganic additives, for the pyrolysis process by keeping the mixture in a small, closed
tubular reactor in the muffle furnace. Seven different RH: FW: ERP: PF ratios were
used; 70:20:5:5, 55:30:7.5:7.5, 40:40:10:10, 75:20:5:0, 75:20:0:5, 50:40:10:0, 50:40:0:10,
respectively. Totally, twenty one different combinations were utilized at 30 minutes
retention time at temperature of 550 ◦C. The produced biochar was evaluated for
its physicochemical properties following the biochar quality standard test protocol.
Biochar generally had a basic pH, while electrical conductivity and total dissolved solids
showed no correlation with mixing ratios. Potassium availability varied with mixing
ratios, increasing with higher PF. Phosphorus availability also varied with mixing ratios,
increasing with higher ERP ratios. The study reported the highest phosphorus content
as 1816.6 mg/L and the highest potassium content as 7986 mg/L. In conclusion, copyrolysis
of organic and inorganic matter seems promising method to manufacturing
biochar with high nutrient content.
