The work aimed at evaluating the performance of an UASB reactor treating domestic sewage pre-treated in a Forced Sieving Unit (FSU) which resulted in size reduction of the influent organic matter particles. The experiments were carried out in two identical demonstration-scale UASB reactors, one with a FSU upstream and the other used as control reactor. The results showed that, after biomass adaptation to new kinetic and hydraulic conditions (low hydraulic detention time followed by high sludge load), the particles size reduction, in the range of 1.8 to 30 µm, resulted in a microbial community selection with higher activity (specific methanogenic activity of 0.072 g COD/g VTS.day four times higher than in the control reactor). This enabled a better performance of the UASB reactor with the FSU, which showed a higher removal efficiency in terms of COD TOTAL (65 versus 54% in the control reactor), and an effluent with lower concentration of COD PARTICULATE (48 versus 74 mg/L in the control reactor).
particles size distribution; domestic sewage; forced sieving; UASB reactor; pre-treatment
