Remoção de cor em efluente sintético através de sistema anaeróbio e microaeróbio

Abstract

The discharge of colorful effluents represents a serious environmetal and public health problem, because, apart from afects the water body’s aesthetic and transparency, as well as gas solubility, many dyes and their by-products are toxic and carcinogenic. The aim of this work was to assess and compare the colour removal of the azo dye RR2 and its aromatic amines in a bioreactor under anaerobic and microaerophilic conditions. The experiment was carried out in a UASB reactor with 3.5 L of useful volume and hydraulic retention time (HRT) of 24h with synthetic effluent containing 50 mg/L of the dye RR2. After that the reactor was microaerated and then supplemented with redox mediator (AQDS) in a concentration of 25 µM. In aerobic conditions, the colour and COD removal efficiencies were 51% and 89%, respectively. However, under microaerophilic conditions the average efficiencies were close to the values found in the last stage. The addition of AQDS increased the colour removal efficiency to 82%, keeping the COD efficiency close to 90%. As well as in the absence of AQDS, the addition of microaeration did not cause significative changes in either colour or COD removal efficiencies. So, to the conditions applied, it was not possible to observe the effect of microaeration in the UASB reactor neither in terms of performance in discoloration nor for by-products (aromatic amines) mineralization of the the synthetic effluent used in the study