Energy recovery in high rate algal pond used for domestic wastewater treatment
P.P. Assemany1*, M.L. Calijuri1, M.H.B. de Souza1 and E.A. do Couto1
1Department 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: 36570900
(free)
High rate algal pond (HRAP) was evaluated according to its energy potential and productivity by two rates, net energy ratio (NER) and specific biomass productivity. All energy inputs were calculated according to one HRAP with pre-ultraviolet disinfection treating domestic sewage. The outputs were calculated for three energetic pathways: biomass burning, lipid and biogas production for the raw biomass and biomass after lipid extraction. The total lipid in dry biomass was 7.37% reaching a daily productivity of 4.6 mg/L and the biogas production potential was 0.22 m³/kg solids. For the biomass after lipid extraction, the biogas production reached 2.55 m³/kg solids, 10 times higher than the biogas potential production of the raw biomass. NER values for the raw biomass were 0.134, 0.0122 and 0.0141 for burning, lipids and biogas, respectively. The specific biomass productivity was 4.26 mg/kJ. For the residual biomass, after lipid extraction, NER value was 0.0173 for the integrated route (lipids + biogas). The biogas generation from the raw biomass was the most favorable energy route.
