Correlations between organic pollution indicators in municipal wastewater

The paper presents the results of a study of parameters used for determining the amount of organic pollutants in wastewater fl owing into a collective wastewater treatment plant with a population equivalent of about 120 000 PE.The plant constituted part of a sewage system.Assays were performed for biochemical oxygen demand (BOD 5 ), chemical oxygen demand (COD Cr ), permanganete index (COD Mn ) and total organic carbon (TOC).In addition, the pH of wastewater and its alkalinity were determined.Sampling of incoming wastewater and measurement of physicochemical parameters were performed once a week, in the spring.A total of 44 samples of wastewater were collected.The correlations between the individual parameters and the correlations between the ratios of these parameters were determined.It was found that it was possible to estimate, with suffi cient accuracy, the values of selected parameters for determining the concentrations of organic compounds in municipal wastewater, knowing the values of other parameters in this group.Moreover, it was shown that, knowing the relationship between the analyzed parameters, one can fi nd multiple regression equations for a given type of wastewater, which allow one to calculate the remaining relationships with a good fi t, i.e. a determination factor R 2 greater than 0.6.