SUMMARY
The importance of this work is the implementation of a natural treatment with low environmental impact. The objective was to evaluate effective microorganisms for there movalofhydrogensul?deon activated sludges of the industrial wastewaters. For the experimental part of the research a bio?lter was built with effective microorganisms, activated sludge and ?lter material. 21 liters of activated EM were inoculated on sludges for over 3 weeks, controlling parameters such uspH, temperature, humidity, oxygen and sun light, guaranteeing the optimal conditions for the develop of photosynthetic bacteria, lactic acid and yeast. Sampling of wastewater was carried out in the closest manhole to the point of discharge of the sewage system of La Iberica and for its analysis at the bio?lter output, taking a sampling with three repetitions each week, for 21 days, to know the initial, intermediate and ?nal concentration of H2S and the removal percentage reached during the treatment. Research ?ndings showed that the effective microorganisms increased the microbialload of the endogenous microorganisms in the sludge,obtaining a better growth of the bio?lm and achieving the reduction of the H2S concentration from 3.68 mg/L to 0.45 mg/L, reaching a removal percentage of 70.35%. This work analyses that to a greater retention times, a better performance of the effective microorganisms is given. The use of effective microorganisms in the removal of H2S is pro?table since the time of action is short and the costs of application are low.