The removal of phosphate in an up-flow anaerobic sludge blanket (UASB) reactor treating a synthetic substrate simulating domestic sewage and its relation with the presence of FeCl3 in the influent was investigated. Phosphate removal efficiencies were 30%, 54% and 84% for influent FeCl3 concentrations of 90 mg.L-1 and 200 mg.L-1, respectively. Scanning eletronic microscopy of granular sludge samples taken from the reactor showed the presence of Methanothrix- like microorganisms as the main predominant methanogenic bacteria. Iron precipitates such as vivianite [Fe3(PO4)2 . 8 H2O] were identified in granular samples by x-ray defraction and energy dispersion x-ray (EDX) analyses
Phosphate removal; synthetic substrate; reactor
