This study was devoted to couple swine slurry bioremediation
with energy production by using microalgae. Even though all tested
conditions efficiently removed NH4
þ and PO4 3, higher biomass
production and faster removal rates were observed at favourable
conditions (i.e. 23 C and 14 h of illumination). The initial NH4
þ load
determined the removal mechanism in batch mode. When
favourable culture conditions were tested in semicontinuous culture
mode, nutrients were as well removed but different N removal
mechanisms were observed along the cultivation.
Under favourable conditions, carbohydrates rich biomass
(50e60% VSS) was obtained when working in batch mode, while
the continuous operation resulted in protein-rich biomass (57%
VSS) probably due to the continuous availability of nitrogen in the
media. Lipid accumulation in the biomass grown under nonfavourable
conditions could have hampered the anaerobic digestion.
Biomass grown under favourable conditions resulted in higher
methane yields and closer to the theoretically methane yield
achievable according to the macromolecular profile. This investigation
highlighted the need of further testing promising results in
batch and semicontinuous mode since different nitrogen removal
mechanisms, biomass macromolecular profile and hence methane
yield were attained.