Anaerobic digestion of pre-treated microalgae biomass

ABSTRACT: Chlorella vulgaris microalgae biomass was cultivated in brewery secondary effluents and used as a recalcitrant effluent to be valorised energetically by anaerobic digestion process. All previous techniques applied for cellular disruption – autoclave, freeze/heating, ultrasound, microwave - provided either high absorption values and release of reducing sugars in the medium or membrane cells damage, compared to the untreated sample, indicating that the pre-treatment action was effective. The highest methane production was attained by the autoclave and untreated microalgae assays (samples with less permeabilized cells) while the lowest was provide by the microwaves biomasses pre-treatment: 163-178 mL versus 67 mL CH4. COD removal of 27-29 % and 16 % and TS removal of 28-32 % and 17 % were obtained, respectively. The corresponding methane yield achieved values of 0.04 and 0.030 L g-1 COD and 0.205-0.235 L g-1 TS related to concentrations determined in the influent.