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Our objective is to determine the changes in the wastewater treatment process in the city of Valencia by taking into account population changes during the period 1983–1990.
We have consulted analytical data and information regarding this volume of water treated in a biological treatment plant of activated sludge; data was collected daily and introduced into a data matrix from which the distribution and central tendency measures were calculated. We then obtained the correlations of the different parameters according to population variations.
We observed an increase in the volume of water treated during our study period: from 74,220 m3/day in 1983 to 183,850 m3/day in 1990. This was in contrast to a gradual decrease in the population of Valencia: 729,900 in 1983 to 699,600 inhabitants in 1990. As parameters indicating pollution, we studied the changes of suspended matter (S.M.) and the biochemical oxygen demand (B.O.D.) in relation to population changes. The variations of the suspended matter produced annually and the population correlate through a second degree polynomial curve with a r = 0.73. The biochemical oxygen demand correlates with the number of inhabitants through a second degree polynomial curve, although in this case r = 0.86.