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Large pig farms generate enormous volumes of wastewater without proper treatment before discharge. High-rate anaerobic reactors as the expanded granular sludge bed (EGSB) are rarely reported for that purpose. In this study, an EGSB reactor with Cuban natural zeolite addition was evaluated for treating piggery wastewaters at lab scale. This study was conducted at different organic loading rate (OLR) ranging from 0.32 to 6.13 gCOD/Ld with a constant hydraulic retention time (HRT) of 12 h. The evolution of several control and operational parameters as the soluble chemical oxygen demand (COD) demonstrated a proper bioreactor performance to treat piggery wastewater. The results showed that the addition of natural zeolite at 40 gzeo/Lreactor in EGSB reactor results in COD efficiencies over 70%, despite of the fluctuations of fed wastewater characteristics. The kinetic study demonstrates that, the modified Stover-Kincannon model was found to be appropriate for EGSB reactor. The effluent soluble COD was predicted with high determination coefficient. The maximum removal rate constant (Umax) and saturation value constant (KB) were reported for a first time for the EGSB reactor with values of 10.2 and 11.8 gCOD/Ld, respectively. Methane yield for both, batch and continues experiments, were in the range from 214.5 to 299.8 mLCH4/gCOD. [ABSTRACT FROM AUTHOR]

The present paper evaluates for the first time, an anaerobic system of UASB-Upflow anaerobic filter (UAF) to treat raw vinasse with and without pH adjustment and without nutrient addition. The anaerobic digestion was properly developed without diluting the vinasse nor with nutrient addition. The best results were achieved with pH adjustment while increasing the organic loading rate (OLR). The stable condition for UASB-UAF system was at OLR 10 and 3 kgDQO m-3d-1 respectively. The methane yield was 0,236 and 0,159 Nm3CH4 kg-1DQOe. It was demonstrated that the use of UASB-UAF system allowed increasing the removal efficiency in terms of COD in more than 90%. A better final disposal of the anaerobic effluents and higher energy recovery was possible. [ABSTRACT FROM AUTHOR]

In this study the stimulus-response techniques are used to study the flow models of two type upflow filters packed reactors, volume of 3,4 to 6 liters respectively, using hydraulic retention times and different tracers in both. The concentration versus time curves for both reactors were determined and comparative analysis of a set of relationships between the different times that were obtained in the graphs was performed. Dispersion Model (Levenspiel) was applied in the same experiments, determined the median time (tm) that the dye is inside the reactor and the degree of dispersion. It was proved that the hydrodynamic models of the two reactors have very similar characteristics, dominated by the tendency of the plug flow and degree of dispersion media. [ABSTRACT FROM AUTHOR]