Parra Huertas, Ricardo AdolfoCampos Montiel, Rafael Germán2015-03-112015-03-1120141909-0455http://hdl.handle.net/10567/1261Introduction. Dairy industry is one of the most important sectors in industrialized and developing countries. Approximately 90% of the milk used in cheese industries is eliminated as whey (or lactoserum). Statistics indicate that lactoserum or whey is discarded as an effluent and brings a serious environmental problem, due to the fact that it affects, physically and chemically, the soil´s structure. This reduces the performance of crops and, when whey is disposed by being pouring it into water bodies, aquatic life is reduced because it drains the dissolved oxygen. Objective. Evaluate a UASB reactor by means of anaerobic digestion, using two organic loads of 3 g/L/.day COD and 4 g/L/. day COD. materials and methods. Different laboratory analyses were performed on both loads: COD, protein, sugars, VFA, methane and ammonium. Results. The results indicated that the COD efficiency was above 65%; the sugars´ degradation was total and the protein degradation was higher that 78%, while the ammonium, methane and VFA concentrations were all within the normal parameters for the reactor´s correct work. Conclusion. The UASB reactor is a god option to treat waste water, as it contains whey in two different organic loads.esCorporación Universitaria LasallistaÁrea Metropolitana del Valle de AburráLactosueroDigestión anaerobiaIndustria lácteaArticle