Avaliação do processo de nitrificação e desnitrificação de efluente de abatedouro bovino em reator combinado anaeróbio-aeróbio

Abstract

The focus of this study was evaluate the efficiency removal of carbonaceous and nitrogen matter, the second through of nitrification and denitrification process, in anaerobic-aerobic packed-bed reactor, subjected to two different recirculation ratio, treating raw wastewater of bovine slaughterhouse. As a support to biomass immobilization, it was used matrices polyurethane under a rigid structure polypropylene. The reactor was operated on bench scale with a useful volume of 4,75L and Hydraulic Retention Time (HRT) of 24h. In the first step, the reactor was operated with recirculation ratio equal to 1. In the second step, the recirculation ratio was equal to 2.The samples were collected along the reactor height. The first step showed better results, with removal efficiency of raw COD, filtered COD, TS and TSS of 56%, 82%, 385 e 73%,respectively, while in second step the removal efficiency to the same parameters were 46%, 68%, 54% e 69%, respectively. As to efficiency removal nitrogen organic matter, of NTK e N-amon, the reactor showed efficiency of 95% e 98%, in the first step and 76% e 81%, in the second step. The concentration of nitrite and nitrate were 0,37 mg.L-1 e 34,4 mg.L-1, in the first step respectively and 0,73 mg.L-1 e 61,9 mg.L-1, in the second step. The most efficiency nitrite oxidation was 75%, under recirculation ratio of 200%, and 35.4% also in recycle 200% of the input. Therefore is possible regard that the nitrification process showed higher efficiency in the second stage which the reactor was submitted, due to the higher concentration of nitrite in that stage. In relation to the denitrification process, if the steps are compared, it is observed that even with the increased recirculation, there was a reduction in the efficiency denitrification, from to 91% in the first step to 67,5% in the second step.