Determinação da capacidade de diluição do estuário do rio Apodi/Mossoró para efluentes da indústria salineira

Abstract

The objective of this work was to determine the dilution capacity of the Apodi / Mossoró River Estuary for effluent from the salt industry. For the mapping of the effluent launching points, field and aid expeditions of the Free Software QGIS (version 2.18.16) were carried out, as well as laboratory analysis of 50 samples collected in the estuary and comparison with other reports and reference resolutions. Of the 20 identified and mapped effluent discharge points, it was observed that the highest concentration of points located in the portion corresponding to the average estuary while the lowest concentrations of points are located in the lower estuary (estuary) and in the region of the upper estuary, being divided in six areas. Regarding the physical chemical analysis of the effluents, it was verified that the temperature, pH and sedimentary materials of the effluents did not change markedly, remaining within the limits allowed by the resolution established by CONAMA and although there is no legislation that determines a limit for Dissolved Oxygen concentration in the effluents, was attacked by the fact that no effluent should cause the reduction of the quality of the receiving body. In this sense, considering that salinity was the parameter with the highest pollutant potential among those analyzed for effluents from the salt industry, it was considered as a base element for determination of the dilution capacity of the estuary and, consequently, of the maximum effluent release rate, assuming some standard values, which resulted in the emission rate of 320 l /s and the maximum flow rate. Based on the observed data and synthesis performed, it is verified that the adoption of the effluent discharge limit estimated in the present work, replacing the current control system, based only on the time limit of disposal, is an alternative to reduce risks of pollution, and minimize conflicts with traditional fisher populations.