INFLUENCE OF THE VARIATION OF TEMPERATURE IN THE REMOVAL OF NITROGEN FROM SANITARY SEWAGE USING A SEQUENCE BATCH REACTOR (SBR) WITH IMMOBILIZATED BIOMASS

Abstract

Conventional treatment systems remove the highest part of pollutants present in the sanitary sewage, however, the most part of these systems present difficulties in the reduction of nitrogen and phosphorus concentrations that can cause hazardous damages to the environment and public health. Biological removal of nitrogen can be obtained by nitrification process followed by denitrification in systems with sequenced batch operation. Thus, this paper sought to evaluate the behaviour of a sequenced batch reactor (SBR) with immobilized biomass in bench scale (10 L) in the removal of nitrogen from the effluent of an anaerobic fluidized bed reactor (AFBR) treating domestic sewage of Campo Mourão, State of Paraná. SBR reactor was operated with cycle of 5.5 h and kept at controlled temperature of 25 °C (phase I) and 35 °C (phase II) during 55 d and 15 d, respectively. With the monitoring of the reactor, it was possible to conclude that the mean efficiency in the removal of raw COD in the phases I and II was 70% and 90%, respectively, showing the influence of the temperature in the achieving of higher efficiency in the removal of organic matter. There was reduction of 28% in the concentration of total solids and of 14% in the mean concentration of total suspended solids. SBR reactor presented mean efficiencies of ammoniacal nitrogen removal of 52% in the phase I and of 42% in the phase II. However, it was noted an accumulation of nitrite in the final steps of the cycle that can be related to the C/N ratio of 2.2 verified in the denitrification phase. It was not verified nitrate concentration in any step of the cycle during the monitoring, indicating the partial nitrification in the reactor. Key words: SBR. Sanitary Sewage. Nitrification. Denitrification. Immobilized Biomass. Post-treatment.