Determinação da demanda bioquímica de oxigénio e da demanda química de oxigénio em águas residuais

Abstract

The chemical oxygen demand and the biochemical oxygen demand are parameters used as indicators in the regulation and control of the environmental quality of domestic and industrial effluents. They can be determined with great accuracy using classical methods. The biochemical oxygen demand is determined by the "Winkler" method with azide modification (iodometric situation) while the chemical oxygen demand is determined with the open reflux method (dichromate titration). The results obtained from the Biochemical Oxygen Demand analysis in different wastewater of the Infulene valley region are compared with the values recommended in Decree n 18/2004 of 2 July. The values obtained are very high compared to the values recommended in the Decree. The same official document recommends a maximum value of BOD equal to 50mg/l to be exerted by a certain industrial effluent. The determinations of the Biochemical Oxygen Demand indicate a relative error of 5%. (TRADUÇAO NOSSA)