Sustainable valorization of sugarcane leaves for succinic acid and biochar production

Abstract

The leaves of sugarcane (Saccharum officinarum) are agricultural waste that is burnt before harvesting. This project aims to find an alternative way to increase the value of sugarcane leaves and decrease air pollution by using the leaves as raw material to produce succinic acid and biochar. Reducing sugars were extracted from the leaves by H2SO4 hydrolysis. The sugars were then fermented by Yarrowia lipolytica TBRC 4417 to produce succinic acid. The solid residue was used as the raw material for biochar production by pyrolysis. The effects of pyrolysis temperature (350, 400, and 450℃) and nitrogen gas flow rate (5, 10, and 15 Lmin-1) on the specific surface area of biochar were determined. The adsorption capacity of mixed nitrogen, phosphorus, and potassium compound solution at various concentrations by biochar was also investigated. The hydrolysis condition was at 1%v/v of H2SO4, 100 gL-1 of sugarcane leaves, and hydrolysis time of 60 min. The hydrolysate yielded sugar monomers at a concentration of ca. 13.00 gL-1 of xylose and 2.00 gL-1 of glucose. The fermentation process of extracted reducing sugar from sugarcane leaves by Yarrowia lipolytica TBRC 4417 was studied at 30℃ for 84 h. with 120 rpm shaking. It was found that Yarrowia lipolytica TBRC 4417 produced succinic acid in glucose, mixed glucose and xylose, and extracted reducing sugars. The maximum succinic acid yield of 0.061 g succinic acid /g sugar consumption was obtained. For biochar production, the maximum specific surface area of 301.19 m2g-1 was found at a pyrolysis temperature of 400℃ and the N2 gas flow rate of 10 Lmin-1. The maximum adsorption capacity of the mixed solution was 28.45 wt%. The adsorption capacity of biochar was N>P>K at a total concentration of 100 mgL-1. This study demonstrates the agricultural waste's potential value as a useful feedstock for the biological generation of succinic acid and biochar.