Biosurfactants Enhanced Methane Production from Organic Solid Waste using Co-culture of Methanosarcina mazei and Pseudomonas aeruginosa

The effect of biosurfactants (surfactin and rhamnolipid) on the methane production from organic solid waste (OSW) investigated using co-culture of facultative anaerobes Methanosarcina mazei and Pseudomonas aeruginosa+Bacillus subtilus. The biosurfactants were applied in the concentration ranges 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5 and 5.g/l respectively. Cumulative methane production (P), maximum methane production rate (R_max) and lag phases (ë) were analyzed using the modified Gompertz model. Results revealed that both the biosurfactants were effective in methane production enhancement. The maximum cumulative methane production of 2.10 L-CH₄/L-substrate and 1.91 L-CH₄/L-substrate recorded at 3.5% surfactin and 3.0% rhamnolipid, respectively. Corresponding highest methane yields were 77.7 mL CH₄/g Carboinitial and 70.7 mL CH₄/g Carboinitial, respectively. The lag phase decreased from 13.9±0.2 hours at control to a minimum of 9.93±0.04 and 10.02±0.02 surfactin and 3.0% rhamnolipid, respectively. Volatile fatty acid generation subsequently increased with biosurfactants additive.