Craft Brewery Wastewater Treatment: a Fixed-Bed Single-Batch Reactor with Intermittent Aeration to Remove COD and TN

Abstract

This study evaluated an intermittently aerated, fixed-bed, single-batch reactor, with mini BioBob© as biofilm media support, as an alternative treatment of craft brewery wastewater. In order to remove chemical oxygen demand (COD) and total nitrogen (TN), seven conditions were performed in a central composite experimental design (CCD) with different aeration times (1, 2 and 3 h in a 4 h cycle) and hydraulic retention times (HRT) (12, 16 and 20 h). The results showed that the removal of COD and TN were positively affected by increased aeration time and HRT. The condition that presented the best quality effluent was Condition No. 1 (20 h HRT and 3 h aeration), with 209 ± 28 mg COD L-1; 3.00 ± 0.15 mg TKN L-1; and 0.67 ± 0.11 mg NO3-N L-1. Kinetic assays showed that the highest values for the substrate removal rate constant, kCOD = 0.1774 h-1were obtained with the longest aeration time (3 h). The most probable number (MPN) test showed a higher concentration of denitrifying bacteria (heterotrophic), 3.3 x 106, than for AOB and NOB bacteria (autotrophic), which were 4.9 x 103and 2.7 x 103, respectively. Moreover, it was possible to verify that correcting the influent alkalinity with 7.14 mg CaCO3for each 1 mg of TKN resulted in better process efficiency. It was concluded that COD and TN can be removed from craft brewery wastewater using an intermittently aerated, fixed-bed, single-batch reactor with mini Biobob©as biofilm media support.