Determinação e correlação dos parâmetros demanda bioquímica de oxigênio, demanda química de oxigênio e carbono orgânico total em águas superficiais

• Autor(a) principal: Melo, Gean Barbosa de
• Data de Publicação: 2022
• Tipo de documento: Trabalho de conclusão de curso
• Idioma: por
• Título da fonte: Repositório Institucional da Universidade Federal do Ceará (UFC)
• Texto Completo: http://www.repositorio.ufc.br/handle/riufc/69965
• topic: Águas superficiais; Matéria orgânica; Correlação

Surface Waters are the main source of access for living beings to fresh water. In the State of Ceará, this resource is relatively low, due to the low average annual rainfall and the semi-arid climate, which favor the evaporation of these waters due to the high temperatures. Moreover, the reservoirs of this resource, including rivers, lakes and dams, can suffer effects through natural or anthropic action, thus observing the quality of the water in the region and leading to various losses for the local population. Among these wastes, organic matter is the main polluting load deposited, a large part of which is composed of carbon. Thus, in this work, the parameters Biochemical Oxygen Demand (BOD), Chemical Oxygen Demand (COD) and Total Organic Carbon (TOC) were determined, in addition to statistically verifying the possibility of replacing BOD and COD by TOC in the experiments experienced. Thus, 11 samples of surface water from the Metropolitan Region of Fortaleza were analyzed in order to quantify the organic matter present through BOD, COD and TOC, following the methods of BOD5, Colorimetric in Closed Reflux and High Temperature Combustion, respectively. Comparing the results with CONAMA resolution Nº 357/05, for class 2 waters, it is verified that only 3 samples have a BOD above the determined limit. In addition, the time of year in which this analysis is performed directly affected its result. In relation to the other parameters, the TOC showed stability in the 7-year interval, while the COD showed an increase during the same time, which may be indicative of a good capacity for self-purification of the water bodies studied. Regarding the statistical correlations, the coefficient of determination (R²) and Pearson correlation coefficient (r) indicated the impossibility of replacing the parameters in the studied samples. Thus, the parameters BOD, COD and TOC were determined in surface waters located in the Metropolitan Region of Fortaleza, in which only COD showed significant variations. In class 2 waters, CONAMA resolution Nº 357/05 indicates that 8 of the 11 samples are suitable for the purposes for which they are intended, through appropriate treatment. Furthermore, the statistical tests showed that it is not possible to replace the BOD and COD parameters with the TOC in these samples, indicating that both analyzes remain essential to monitor the water quality in this region.