Volatile fatty acids as an added value from biowaste

Area of Science:

• Biotechnology
• Environmental Science
• Microbiology

Background:

• Volatile fatty acids (VFAs) are valuable chemicals. Traditional production methods often rely on anaerobic conditions.
• Kitchen biowaste and potato peels are abundant, underutilized feedstocks for bioprocesses.

Purpose of the Study:

• To demonstrate the feasibility of using a co-culture of K. mobilis and E. coli for VFA production.
• To investigate VFA production and chain elongation from kitchen biowaste and potato peels under microaerobic conditions.
• To compare findings with existing research predominantly focused on anaerobic VFA production.

Main Methods:

• Pilot-scale experiments were conducted using a 250L bioreactor.
• Co-culture of K. mobilis and E. coli was employed.
• Microaerobic conditions with pH control (6.0-6.5) and varying feeding strategies were tested.

Main Results:

• Acetic acid and ethanol were initial products, followed by propionic, butyric, and valeric acids.
• The highest yield (325mg/g TS) was achieved at 99.1g TS/L substrate load and pH 6.5, with a productivity of 448mg/L/h.
• The longest average VFA chain length (3.77C) was observed at 63.2g TS/L loading and pH 6.0.

Conclusions:

• The K. mobilis and E. coli co-culture symbiosis promotes VFA formation and chain elongation, likely due to enhanced ethanol production.
• Microaerobic conditions offer an alternative to anaerobic processes for VFA production.
• The study provides a foundation for optimizing VFA production from biowaste using this co-culture system.