With regard to the microalgae biomass harvested after wastewater
treatment, biogas production is probably one of the simplest
applications. Anaerobic digestion (AD) is a straightforward technology
for microalgae biomass valorization. AD is preferred over
biodiesel or bioethanol production since it avoids the drying step of
the biomass and the three macromolecules (namely carbohydrates,
proteins and lipids) are converted to biogas. The production of
biogas is determined by the resistance of microalgae cell wall and
the macromolecular composition of the microalgal biomass. This
macromolecular composition is determined by the nutrient availability
in the growth media. Thus, high nitrogen and phosphorus
concentrations promote protein production while a shortage of
nutrients results in carbohydrate- or lipid-rich biomass, depending
on the microalgae strain [8e10].
The first objective of the present work was to evaluate the ability
of a microalgae consortium for biomass production using swine
slurry as growth media. The different mechanisms involved in
slurry bioremediation at two ammonium loads under different
environmental conditions (winter and summer conditions) were
studied in batch mode. The best condition (summer and high NH4
þ
load) was further studied in semicontinuous mode for comparison
purposes with the batch experiment. The collected biomasses were
subjected to anaerobic digestion to evaluate the effect of the
cultivation parameters on the final methane yield.