Arango Ruiz, Álvaro de JesúsGarcés Giraldo, Luís Fernando2012-07-172012-07-172012-07-171909-0455http://hdl.handle.net/10567/550Liquid effluents from several industrial processes have been treated by the use of electro coagulation, obtaining promising results in the removal of pollutants. This technique has been especially studied in the treatment of waste water from dairy industries. Electro coagulation is a treatment that allows the removal of pollutants from liquid effluents, by applying electric energy into the liquid and, thus, destabilizing the electric loads of the suspended and dissolved solids, producing their precipitation to the bottom and making their separation possible. There are several parameters to control in this process, such as pH, electric conductivity and electric current density, among others. Objective. To study the influence of electric conductivity of waste water from dairy industries in the removal of COD. Materials and methods. Waste water from dairy industries was treated with electro coagulation, using an experimental factorial 3x2x3 design that acts according to the variations of conductivity, current density and treatment time. The response variables measured were the COD removal percentages. Results. The percentage of COD removal was favored with the increase of current density from 32.42 to 43.23 A/m2 at a 15 minutes treatment time. Concerning the conductivity of the aqueous medium, it was also observed a higher removal rate when this parameter was increased from 1.5 to 2.5 S/cm, but when it was increased to 3.5 S/cm a reduction in the removal was observed. This indicates that a conductivity increase above 2.5 S/cm is not effective for the COD removal efficiency. Conclusion. The result of this study allows to say that the optimal level for treating waste water from dairy industries by the use of electro coagulation is achieved at a 15 minutes treatment time, 2.5 S/cm conductivity and a 43.23 current density. It results in a COD removal of 95.9%.esElectrocoagulaciónCorporación Universitaria LasallistaÁrea Metropolitana del Valle de AburráIndustria lecheraAguas residualesContaminación del aguaTratamiento de aguas residualesAguas residuales industrialesConductividad eléctricaArticle