Taynan de Oliveira Costa1*, Jackeline de Siqueira Castro1, Maria Lúcia Calijuri1, Paula Peixoto Assemany1, Eduardo de Aguiar do Couto1
1 Department of Civil Engineering, Núcleo de Pesquisas Ambientais Avançadas – nPA, Universidade Federal de Viçosa, Av. P.H. Rolfs – Campus da Universidade Federal de Viçosa – Viçosa, MG – Brazil – Postal Code: 36570-900.
The algae biomass harvest from high rate algal ponds (HRAPs) is one of the biggest challenges with regard to the use of energy, since the algae cells are very difficult to remove due to their small size, the density similar of the water and the strong negative surface charge. Higher harvesting efficiency of algal biomass can be promoted by increasing the dominance of algae species readily liable for sedimentation. This study assessed if biomass recirculation in HRAPs can promote the dominance of genera with best sedimentability features, which would improve the biomass separation and, therefore, increase the productivity of harvestable biomass in the pond. For that purpose, two HRAPs with ultraviolet pre-disinfection and CO2 addition were compared, one with recirculation and one control (without recirculation). By the analysis of the results, it was possible to observe that the dominance was different in the two ponds. An improvement in the efficiency of biomass harvesting was also observed, 46.89% in pond with recirculation and 30.85% in the pond with no recirculation. However, the obtained harvesting was low and even inefficient when compared with other studies found in the literature. In addition, there was no positive influence of recirculation on nutrients and organic matter removals efficiency.