The mass balance was acquired out in order to determinate the mean values of chemical oxygen demand (COD) and methane (CH4) production from two UASB reactors treating swine wastewater subjected to distinct operational conditions in respect to concentrations of total suspended solids of the affluent (TSS of 500; 1,000; 1,500 and 2,000 mg L-1), hydraulic detention time (HDT of 30; 20; 12 and 8 h), volumetric organic loading rates (VOLR of 0.8 to 8.0 kg COD (m³ d)-1) and temperature (ambient, 25 ºC and 30 ºC). It was verified that values of total COD removed and converted in CH4 varied from 28 to 51% and the ratio values of COD-CH4 by removed and dissolved COD varied from 0.94 to 2.07; indicating a high participation of physical removal (49 to 72%) of the affluent solids in the process. The TSS concentrations, temperature, HDT and VOLR influenced the UASB reactors performance.
anaerobic digestion; anaerobic treatment; swine waste
