Efeito do corante azo reactive black 5 no processo de granulação aeróbia em reator em batelada sequencial

Abstract

In the present work, the impact of the azo dye Reactive Black 5 (RB5) on the process aerobic granulation, granule stability and matter removal performance organic and nutrients (nitrogen and phosphorus) from an aerobic granular sludge (LGA) system. The impact of azo dye RB5 on the stability of aerobic granules and on performance of removing organic matter and nutrients (nitrogen and phosphorus) from a system of LGA whose biomass was previously granulated in the absence of dyes. Also, removing of color was evaluated in the absence and in the presence of different concentrations of the redox mediator anthraquinone-2,6-disulfonate sodium (AQDS). The granulation process took place satisfactorily in the presence and absence of the RB5 dye. In the presence of the dye, the granules presented worse sedimentability and smaller dimensions than those formed in the absence of dye. Therefore, the dye interfered with the physical characteristics of the granules. However, these showed high degradation performance of different pollutants. The reactors showed excellent COD removals (greater than 95%). Regarding nitrogen, the systems have almost completely oxidized ammonia (nitrification), but accumulations of nitrate and nitrite, indicating difficulties in the denitrification process. At Phosphorus removals were low when compared to reported values ​​for LGA systems. The addition of RB5 dye to the system tributary with previously granulated biomass in the absence of dye reduced sedimentability and granule size. However, large variations in COD removal efficiencies were observed in the two systems, and the values ​​remained above 85% during almost the entire experiment. Regarding fractions nitrogen, a greater accumulation of nitrate occurred in the reactor supplemented with dye, indicating better denitrification in the system operated without dye. As for phosphorus, the efficiencies removal in both systems were similar and relatively low. Finally, adding of the redox mediator AQDS and the increase in its concentration increased the removal efficiency dye RB5, however the residual color still remained relatively high, especially for proper disposal of the effluent.