Validación de la determinación de oxígeno disuelto y demanda bioquímica de oxígeno en aguas y aguas residuales

Abstract

Inside the methods of determination of OD the more employee is of the method yodométrico (or of Winkler), it is very laborious, being also needed, to achieve good results, to have an analyst trained in the determination of the final point of the valuation, for this method or his modifications are subject to due serious errors to interferences. In the literature other methods of determination appear among those that meet the methods of determination for membrane electrode like variants with the objective of diminishing the errors, as well as the analyst's manipulation. The DBO is defined as the quantity of oxygen required by the microorganisms, to stabilize the material organic biodegradable present in the residual one, under aerobic conditions. Their determination is carried out, usually, by means of the mensuration of the Dissolved Oxygen of a sample before and after a period of incubation that is generally of five days, defined conditions for the biological oxidation of the organic matters. The present work offers the results obtained in the validation of the determination of OD and DBO by means of the employment of membrane electrodes in waters of different origins. In the validated method a Coefficient of Variation of 1,1% was obtained, a Recovered of 99,82% and a total Uncertainty (95% of trust) of 0,1 mg/L.