Biomethane Production From Residual Algae Biomass (Ecklonia maxima): Effects of Inoculum Acclimatization on Yield

This paper presents the effects of inoculum acclimatization on biomethane production from extraction residues of the seaweed (Ecklonia maxima) via anaerobic digestion. Anaerobic digestion of Ecklonia maxima has been studied with and without acclimatized inoculum under mesophilic conditions (similar to 37 degrees C) for a digestion period of twenty (20) days. The acclimatized inoculum-seaweed sample recorded the highest methane yield of similar to 862 ml CH4/gVS (similar to 55% of the total biogas produced) compared to the similar to 580 ml CH4/gVS recorded for the non-acclimatized inoculum-seaweed sample, both within the first ten (10) days. Kinetic studies on acclimatized and non-acclimatized samples were carried out using the modified Gompertz model. The model showed coefficients of determination (R-2) of 0.99 and 0.98 with an estimated yield rate (mu) of similar to 296 ml/gVS/day (0.4 days phase lag, lambda) and similar to 60 ml/gVS/day (3.4 lambda) for the acclimatized and non-acclimatized samples respectively. The Fourier transform infrared spectroscopy (FTIR) analyses revealed the presence of carboxylic, hydroxyl, ketone and ether groups which further corroborated the suitability of E. maxima for biogas production. The implications of the results are discussed to elucidate the potential of seaweed as a renewable energy source for macroalgae biorefinery.

Automated summary

Acclimatization of inoculum significantly improves biomethane production from seaweed extraction residues through anaerobic digestion, as evidenced by higher methane yield and kinetic model analysis. Fourier transform infrared spectroscopy further confirms the suitability of Ecklonia maxima for biogas production.