Improvements in non-aseptic methods for fungal cultivation on corn-ethanol thin stillage and continuous hydrothermal liquefaction of fungal biomass feedstock

Cultivation of Rhizopus oligosporus and Mucor circinelloides on corn-ethanol thin stillage has been reported to significantly remove COD, TSS, glycerol and organic acids; making in-plant water reuse much more viable while producing a protein-rich animal feed biomass with a high oil content and valuable fatty acids. As fungal biomass cultivation is scaled up from lab to bench and pilot scale, aseptic methods become difficult and cost prohibitive. Non-aseptic fungal cultivation on thin stillage has been reported to have fungal and bacterial contaminants resulting in reduced biomass yields. Chemical oxidizers sodium hypochlorite, chlorine dioxide, iodophor and ozone along with antibiotics penicillin-streptomycin were tested as potential selective disinfectants to enhance fungal biomass yields. Fungal biomass grown on thin stillage also has the potential to be a promising feedstock for advanced biofuels due to its short 2-3 day fermentation period and high oil content. Drop-in biofuel consumption is projected to more than double from 2014-2019. Fungal biomass feedstock for thermochemical processing to produce bio-crude oil that is upgradable to drop-in renewable diesel could help to meet this increasing demand. Suspended growth fungal biomass cultivated in thin stillage has a high moisture content making aqueous-phase processing through hydrothermal liquefaction (HTL) a favorable thermochemical process for generating biofuels compared to dry feedstock required for traditional gasification and pyrolysis. Continuous HTL of fungal biomass using a 1.5L supercritical flow reactor to produce bio-crude oil was accomplished. The fungal bio-crude oil was then analyzed and compared with microalgae bio-crude oil produced by like methods