Stimulation of methanogenesis in a laboratory scale UASB reactor treating domestic sewage by Fe(0) application.

The effects of application of zero valence Fe (Fe(0)) on the anaerobic digestion of sewage was investigated using two laboratory scale UASB reactors. One reactor had Fe(0) addition in a container found midway along the recycling loop. The other one was a control reactor. In a test run period of 76 days, the Fe(0) application significantly increased the CH, yield by 8.7% and decreased the effluent COD concentration by 21.0% relative to the control reactor. A decrease of the H, concentration of biogas and the CODs/CODt ratio in effluent by Fe(0) application were observed. The obtained results imply that the methanogenesis and COD removal efficiency of the UASB reactor were stimulated by Fe(0) application. The higher performance of the reactor with Fe(0) application arises from the integrated functions of Fe(0) or its ionic state as donor of H2, macronutrient, and flocculant. This study showed that the supply of Fe(0) to a UASB can improve the methanogenesis and the overall COD removal of a UASB reactor treating low-strength domestic waste water.