Avaliação de estratégias de armazenamento do lodo granular aeróbio visando o tratamento de águas residuárias

Abstract

An interesting alternative to accelerate the start-up of aerobic granular sludge reactors (AGS) is the use of previously formed granular biomass, from another system, as an inoculum. In this context, the adoption of effective strategies for granule storage and reactivation is of great importance. Therefore, the objective of the work was to evaluate the storage of aerobic granules in different conditions and their reactivation in a simulated domestic sewage treatment system, aiming at the best storage condition to preserve the structure and bioactivity of the granules. The granules were stored at 5 ºC with tap water (Test 1), synthetic sewage (Test 2), ammonium+phosphate solution (Test 3) and saline solution with a concentration of 35 gNaCl/L (Test 4), for 60 days. Then, the reactivation of the granular biomass stored in each condition was evaluated in small flasks, simulating a cycle test of a sequencing batch reactor from which the granules were collected. It was observed that the granules stored with tap water (Test 1) and synthetic sewage (Test 2) showed better performance in the removal of COD, NH4 + and PO4 3- . Subsequently, two reactors (R1 and R2) were used to evaluate the start-up time (time needed to reach the performance compatible with that before storage) in a continuous system with the biomass subjected to Tests 1 and 2. Over 20 days, the results showed that the storage of the granules with substrate (synthetic sewage) provided better preservation of the morphological, structural and biological characteristics of the granules and fast reactor start-up (4 days) in the reactivation process.