Water chestnut shell as a novel substrate for biosurfactant production: Enhanced oil recovery and soil decontamination

Abstract

In the realm of green chemistry, biosurfactants derived from fruit and vegetable wastes have garnered substantial interest due to their environmentally friendly applications. This study investigates the utilization of water chestnut shell powder (WCSP) as a novel substrate for biosurfactant production from Pseudomonas aeruginosa IITR110 and Bacillus velezensis IITR111. The extracted biosurfactants were identified as rhamnolipid and lipopeptide, with a yield of 1.18 g/L and 0.99 g/L, respectively. Their emulsification activities against crude oil demonstrated an E₂₄ value of 60.5 ± 1.8 % with rhamnolipid and 64.9 ± 1.4 % with lipopeptide. These biosurfactants exhibited robust stability across a wide range of pH 2.0–13.0, temperatures 4–120 ºC, and salinity levels 1–20 %, NaCl. The biosurfactants were employed in soil washing assay in which biosurfactants from IITR110 and IITR111 resulted in crude oil removal rates of 52.12 % and 58.03 %, respectively, outperforming the synthetic surfactant tween 20 (50.71 %). The sand pack column experiments revealed a substantially enhanced oil recovery percentage of 36 % for rhamnolipid and 43 % for lipopeptide. The novelty and significance of this study lie in the innovative use of water chestnut shell powder as an alternative substrate for biosurfactant production, thus presenting a sustainable and previously untapped approach.