Sophorolipids Production from Oil Cake by Solid-State Fermentation. Inventory for Economic and Environmental Assessment

Abstract

Biosurfactants are being proposed as a substitute for surfactants in the framework of a circular economy strategy. Sophorolipids (SL) are a type of biosurfactant produced by yeast that can be produced through submerged or solid-state fermentation (SSF) processes. Even though sophorolipids are being produced at full scale, through submerged fermentations, environmental and technoeconomic information regarding its production through SSF is unavailable. An inventory of data necessary to perform preliminary economic and environmental assessments is presented in this study. Data was obtained from three SSF processes at 22-L reactor volume and from two SSF processes at 100-L reactor volume, using winterization oil cake and molasses as substrates, wheat straw as support material, and Starmerella bombicola as SL producing yeast. The effect of increasing the operation scale was assessed. Besides presenting parameters such as inoculum production, initial mass of substrates, and airflow requirements; process emissions (NH3, Volatile Organic Compounds, N2O, SH2 and CH4) and the biogas potential of the spent fermentation solids were also presented.

Microbial biosurfactants: a review of recent environmental applications

“…The biosurfactant extract with a capacity of dispersing 90% of oil drops in seawater was produced using two low-cost substrates (corn steep liquor and ground-nut oil refinery residue) in 20-L bioreactors obtaining a yield of 21 g L −1 at 144 h, similar to that obtained at lab-scale. Comparably, 37 ,used winterization oil cake and molasses as low-cost substrates for biosurfactant production in an SSF process with 22-L and 100-L reactors with S. bombicola , achieving a yield of 0.19 gSL gDM −1 and 0.14 gSL gDM −1 , respectively, showing the production adaptability that this microorganism presents. It should be highlighted that SSF is carried out using solid substrates where microorganisms grow in the absence of free water.…”

A Simplified Techno-Economic Analysis for Sophorolipid Production in a Solid-State Fermentation Process

“…The base scenario was based on previous work performed at different scales, with reactor volumes of 500 mL [9], and 22 and 100 L [29]. These studies demonstrated the feasibility of the production of SL through SSF at bench and pilot-scale, using winterization oil cake (WOC) and molasses (MOL) as substrates, wheat straw (WS) as the support material to provide porosity and resistance to compaction, and S. bombicola ATCC 22214 (American Type Culture Collection, Manassas, VA, USA) as the SL-producing yeast.…”

“…Under these conditions, the productivity is 0.026 g SL/g dry matter d, and the obtained production yield is 0.72 g SL/g fat (corresponding to 0.26 g SL/g WOC). Based on the results obtained for 100 L reactors, we considered a scale-up factor and assumed to achieve 85% of the SL yield obtained in our previous works, as a conservative value in the simulation [29].…”

“…The clean extract is then derived to the SL recovery stage, and the residual biomass is sent for treatment. The models consider costs for spent solids managed through anaerobic digestion in an existing industrial facility in the region, since biomethane production potential has been confirmed in the range of biowaste [29].…”

“…Recently, we have demonstrated the feasibility of producing SLs from oil cake and molasses from the food industry by SSF at a representative scale [29]. Also, the system can admit different lignocellulosic materials as supports [30].…”