Conversion of chicken feather waste via hydrothermal carbonization: process optimization and the effect of hydrochar on seed germination of Acacia auriculiformis

Using statistical response surface methodology this paper primarily investigates the role of process parameters at different levels (temperature, contact time, and rotation speed) and their influence on yield percentage during the production of chicken feather hydrochar (CFH) as soil amendment. Later, the produced char samples were evaluated before and after washing to assess the phytotoxic effect of seed germination and growth on Acacia auriculiformis through germination index% (GI). The optimized conditions for temperature, contact time, and rotation speed of hydrochar production were 150 degrees C, 1 h and 105.65 rpm, respectively. The hydrochar yield percentage at optimized conditions was 51.93%. The seed germination test indicated strong phytotoxicity for soil with untreated char, fresh hydrochar extract (FHE) with high doses, and 4 months old hydrochar extract (OHE) but the toxic effect was lower for washed hydrochar extract (WHE). It showed a higher germination rate and growth performance for washed hydrochar extract among all the doses. This study has confirmed the applicability of chicken feather (CF) hydrochar for improving the physical properties of sandy loam soil. Further research into pre-treatment and assessment of hydrochar before field application is required.