Remoção de nutrientes em reatores anaeróbio-aeróbio seguido por um filtro percolador

This study aimed to evaluate the performance of a combined system used in nitrogen and phosphorus removal, with a variation of the hydraulic retention time (HRT) and the recirculation rate (R). The system consisted of three sequential reactors operated in series, composed of an anaerobic reactor (20 L), an aerobic fixed bed reactor (19 L), and a trickling filter (16 L). The recirculation rates of 150, 100, and 50% and HRT of 9, 7, and 5 h have been, with a constant aeration flow of 10 L min-1. For system evaluation, liquid temperature, pH, total alkalinity, bicarbonate alkalinity, volatile acids, dissolved oxygen, chemical oxygen demand, Kjeldahl total nitrogen, nitrogen ammonia, nitrite, nitrate, and total phosphorus have been analyzed. The combined system has reached achieved organic matter removal efficiencies of 99%, 98%, and 98% for the recirculation rates of 50, 100, and 150%, respectively. Under the same R rates, TKN removal efficiencies resulted in 96, 89, and 87%, and TP removal efficiencies in 78, 82, and 77%, respectively. When operated with HRT of 9, 7, and 5 h, the combined system achieved removal efficiencies of 86, 96, and 98% for COD, 90, 93, and 94% for TKN, and 74, 89, and 95% for TP, respectively. The best operational condition was experimentally established having with a recirculation rate of 150% and HRT of 5 h. However, after experimental validation by CCRD (through desirability), the optimal operational condition resulted in a recirculation rate of 123% and HRT of 5 h for TKN and PT removal efficiencies.