ORGANIC MATTER, NUTRIENTS AND COLIFORMS REMOVAL IN A TWO-STAGE ANAEROBIC PROCESS (ANAEROBIC BAFFLED REACTOR FOLLOWED BY UASB REACTOR) FOR SWINE WASTEWATER TREATMENT

In this work it was evaluated the effect of swine wastewater with mean total suspended solid (TSS) concentration ranging from 4.591 to 13.001 mg L-1 on the performance of the anaerobic process in two stages composed of anaerobic baffled reactors (ABR) and an upflow sludge blanket reactor (UASB), installed in series, in pilot scale testing ( volumes of 530 and 120 L, respectively) and with hydraulic detention times (HDT) of 60; 36 and 24 h in the ABR reactor and 13.6; 8.2 and 5.4 h in the UASB reactor. The mean CODtotal removal efficiency varied from 69 to 84% in the ABR reactor and from 39 to 58% in the UASB reactor, resulting in average values ranging from 87 to 94% for the two-stage anaerobic treatment system under organic loading rate (OLR) of 11.5 to 18.0 g total COD ( L d)(-1) in the ABR reactor and 4.2 to 13.4 g total COD ( L d)(-1) in the UASB reactor. The maximum volumetric methane production of 0.227 m(3) CH4 ( m(3) reactor d)(-1) occurred in the UASB reactor with OLR of 10.6 g total COD ( L d)(-1) and HDT of 5.4 h. The most removal efficiencies of thermotolerant coliforms (99.7), diss COD (94%), TSS (96%), NTK (71%), P-total (61%) and other minerals in the two-stage anaerobic treatment system was obtained with HDT of 73.6 h and medium air temperature of 24.6 degrees C, applying the minor OLR of 11.5 g total COD ( L d)(-1) in the ABR reactor and 4.2 g total COD ( L d)(-1) in the UASB reactor with the biggest affluent TSS (13.001 mg L-1).