Avaliação de reator anaeróbio operado em bateladas sequenciais com biomassa imobilizada (AnSBBR) visando à produção de hidrogênio a partir de água residuária de fecularia de mandioca

Abstract

Anaerobic sequencing batch biofilm reactors (AnSBBR) have been used successfully in wastewater treatment. Currently, this setting has been used for biological production of hydrogen from synthetic and complexes substrates with reasonable results in stability and productivity. Considering the good performance achieved by such configuration, an AnSBBR reactor with a 6.0-L total capacity and a 4.3-L useful volume (2.3-L residual volume and 2.0-L treated volume by cycle) was evaluated, since its goal was hydrogen production, whose substrate was cassava wastewater. Eight experimental conditions were evaluated, in which four volumetric organic loads were applied (5.0; 12.0; 14 and 18 gCarb.L-1 d-1) calculated according to influent concentration (2,000; 3,200; 4,200; 4,700 and 5,000 mgCarb.L-1) and cycle time (4; 3 and 2 h). The AnSBBR feeding of the system was carried out by varying the reactor filling time. Thus, assays were carried out in: i) batch, in which the reactor filling occurs in 20 minutes; and ii) fed- batch, in which the reactor filling occurs during 50% of the total cycle time. Reactor inoculation was carried out with mixed cultures from autofermentation of cassava wastewater and anaerobic sludge that was thermally treated. The highest molar productivities were 36 molH2.m-3.d-1, while volumetric productivity was 2.2 LH2.L-1.d-1 (applied volumetric organic load of 14 g.L-1.d-1) and molar yield was 4.9 molH2.kg-1Carb (applied volumetric organic load of 12 g.L-1.d-1) in assays with the highest cycle times (4 h), inoculated with anaerobic sludge and autofermented cassava wastewater. Lactic acid and bacteriocin nisin were recorded in all the studied assays, consequently, it is evident the presence of lactic bacteria. Therefore, the total hydrogen absence can be explained in both assays, inoculated with autofermented cassava wastewater.