Biorreator combinado anóxico-aeróbio de leito fixo para remoção de matéria orgânica e nitrogênio de efluente lácteo

Abstract

This study measured the performance of an anoxic-aerobic combined fixed bed bioreactor (pilot scale) operated in continuous mode, with upflow and recirculation using plastic filler filled with polyurethane foam as support material for immobilization of biomass applied to the treatment of dairy wastewater aiming at the removal of carbonaceous organic matter and nitrogen. During the first two steps we evaluated the performance of removal of organic matter (COD) and conversion of total Kjeldahl nitrogen (TKN-N) of anaerobic modules operating under 48h and 24h of hydraulic retention time (HRT). In the following two steps was coupled aerobic modules, evaluating the performance gain of organic matter removal and conversion of nitrogen by applying affluent without recirculation and with different volumetric organic loads (VOC) applied, confirming that this value does not exceed 2 KgDQO.m-3day-1 to effective nitrification process, as was noted inhibition of nitrite-oxidizing bacteria due to the presence of free ammonia in sample. During the last two steps, was started re-circulating effluent to stimulate denitrification, and were applied the conditions of the recirculation ratio 1:1 and 2:1. The COD removal efficiency, TKN-N and total nitrogen (N-Nt) were 96.0%, 94.2%, and 30.9%, respectively during the Step 5. It was verified that the performance and stability of the bioreactor concerning to the removal of carbonaceous organic matter and nitrogen is related to the VOC applied, and when the VOC applied is less than 2 KgDQO.m-3day-1 is possible to reach the release patterns effluent disposed by Brazilian environmental legislation.