Probiotic effects of anaerobic co-digestion substrates

Area of Science:

• Environmental Microbiology
• Biochemical Engineering
• Sustainable Energy

Background:

• Anaerobic digestion is crucial for waste management and renewable energy production.
• Manure is commonly used as a co-substrate to stabilize anaerobic digesters, particularly with high-energy feedstocks like whey.
• Previous studies attributed manure's benefits to alkalinity, nutrients, or trace elements, but the microbial contribution remained unclear.

Purpose of the Study:

• To investigate the role of naturally occurring microorganisms in manure and stored whey on biogas production during co-digestion.
• To determine if the beneficial effects of manure in anaerobic digestion are primarily due to its microbial community, acting as a probiotic.

Main Methods:

• Co-digestion of casein whey and cow manure with primary sludge in anaerobic digesters.
• Comparison of biogas production in reactors with untreated manure/whey versus autoclaved manure or filtered whey.
• Quantification of biogas yield relative to a control reactor using only primary sludge.

Main Results:

• Co-digestion with untreated manure and whey increased biogas production by 151.1% compared to the control.
• Autoclaving manure to eliminate microorganisms reduced biogas production to 112.8% of the control.
• Filtering stored casein whey to remove microorganisms decreased biogas production to 112.9% of the control.

Conclusions:

• The microbial community in cow manure exerts a significant beneficial, probiotic effect on anaerobic digestion performance.
• Microorganisms developed during the storage of casein whey also play a critical role in enhancing biogas production.
• These findings highlight the importance of microbial interactions in optimizing co-digestion processes for biogas generation.