Decontamination and Valorisation of a Corn-to-Ethanol Biofuel Waste Stream

The transition toward net carbon zero energy production has accelerated global biofuel production, resulting in the generation of novel, complex waste streams which challenge conventional treatment methods. This study investigates the physiochemical characteristics, decontamination and valorisation potential of a tertiary waste stream (TWS) produced during a corn-to-ethanol whole stillage upgrading process. Rheological analysis revealed that TWS exhibits non-Newtonian, pseudoplastic behaviour driven by interaction between fibrous solids and oil-based components, rather than by soluble components such as glycerol. Chemical oxygen demand (COD) measurements indicated extremely high organic load present (estimates of up to 428 g/L), while microscopy and high-performance liquid chromatography (HPLC) confirmed a heterogeneous emulsion-suspension comprising oils, fibres and polar compounds. Bioelectrochemical system (BES) treatment, an emerging wastewater treatment technology, was evaluated as a biological remediation strategy for TWS. Although microbial conversion of glycerol, lactic acid and potentially long-chain hydrocarbons were observed, electrochemical performance was limited by viscosity and mass-transfer constraints. In contrast, liquid-liquid extraction using n-heptane as a solvent effectively partitioned TWS into three distinct fractions: an oil-rich organic phase, a fibrous intermediate middle phase and a low-viscosity aqueous phase. GC/MS, HPLC and microscopy revealed distinct chemical and structural profiles for each recovered extraction phase, highlighting opportunities to transform TWS into more manageable and value-added streams. Collectively, these results form the basis for an integrated circular valorisation strategy that integrates targeted solvent extraction with complementary biological treatment to convert a complex stream into processable fractions, enabling resource recovery and significantly reducing waste in a biofuel production process.<p></p>

Author dc:creator

• Chloe Beney (21048506)

• Biofuel waste streams
• Bioelectrochemical systems
• Waste valorisation
• Liquid-liquid extraction
• C-zero energy transition

Statement dc:rights

• All rights reserved
• Open Access after 2031-06-15

Identifier

10779/exe.32625984.v1

OAI identifier oai:identifier

oai:figshare.com:article/32625984