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Poster Abstract

Effect of mixing frequency on biogas yield in biodigesters

Hala Chaoui and Tom Richard
Postdoctoral Scholar, Agricultural and Biological Engineering
The Pennsylvania State University

Mixing biodigesters might either increase or decrease methane yield. Mixing disrupts bacterial growth yet brings substrates to bacteria, which it degrades into organic acids and hydrogen, used to reduce CO2 to methane. This study examined the effect mixing frequency on the methane yield of lab scale batch biodigesters. The mixing frequencies were once, twice and three times a day, lasting one minute each. Results showed that a 3 fold increase in mixing frequency significantly decreases biogas volume. Mixing also reduces the waste stability of the digesters' effluent. Optimal biodigesters mixing frequency and mixer velocity need to be investigated.