Orthogonal experiment was conducted to study the ability of effective microorganisms(EM) in decomposing organic matter of domestic sewage. It showed that EM could remove organic matter in domestic sewage and it had the best result in following conditions: water temperature (25℃), hydraulic retain time (HRT, 48 h ), EM addition (VEM/V, I/10), blast time (HRT/3 )and sewage PH (8. 0). Based on these, the removal percentage of COD and BOD in domestic sewage containing EM was determined and checked against the value without EM. The former had a muc...