Influência da configuração do reator batelada sequencial no cultivo da biomassa granular aeróbia

Abstract

This work evaluated the impact of two sequential batch reactor (SBR) configurations (conventional and constant volume) used for the cultivation of aerobic granular sludge (AGS) in relation to the physical and microbiological characteristics of the granules, and the capacity of simultaneous removal of carbon, nitrogen and phosphorus. In the conventional SBR (R1), the filling, reaction, settling and decanting phases occurred sequentially, while, in the SBR operated at constant volume (R2), the filling and decanting phases occurred simultaneously followed by the reaction and settling phases. A faster formation of granules (about 30 days) with a larger size (∅ > 1 mm) and better settleability (SVI30 ≈ 44.8 mL/g) was observed in R1. On the other hand, R2 presented a slower formation of granules (about 50 days) with a smaller diameter (±0.8 mm) and a worse settleability (SVI30 ≈ 70.7 mL/g). Although R2 presented smaller granules (and longer time for biomass formation), this configuration presented several advantages, such as better system stability during the entire operation (125 days), higher solids retention, and granules with better physical resistance. In terms of performance, both systems presented high values of COD (> 90%), NH4 + (> 90%) and TN (> 50%) removals after stabilization. However, the phosphorus removal in R2 was higher (≈ 50%) than in R1 (≈ 25%). The results justify the use of SBRs operated at constant volume in most full-scale AGS wastewater treatment plants, such as Nereda®. Therefore, the SBR configuration has a direct influence on the granule formation and its physical and microbiological characteristics as well as on the system performance in terms of efficiency and operational stability.