Experimenting biochemical oxygen demand decay rates of Malaysian river water in a laboratory flume

Abstract

Mathematical models used to simulate the water quality and the processes of self-purification of water bodies are important tools to support effective water resource management. The objective of this study was to evaluate the impact of organic pollution on water quality and the assimilative capacity of organic matter in the Ribeirão Vermelho stream situated in the city of Lavras in Minas Gerais. The deoxygenation rate (K 1 ) and reaeration (K 2 ) were determined and tested in three segments of the Ribeirão Vermelho over two seasons (summer and winter). The purification process simulation was performed using the StreeterPhelps model. The highest K 1 and K 2 values occurred during the winter period which was characterized by lower flows. Simulation of the dissolved oxygen profile and biological oxygen demand fitted the model well, indicating the prevalence of carbonaceous deoxygenation due to nitrification and also demonstrating the importance of natural reaeration as part of the purification process. Different response was observed during the winter, in which the high primary productivity values stood in the reaeration process stream. Biological oxygen demand values did not meet the limits recommended by the Resolution of the Ministry of the Environment 357/2005 throughout the river system and the entire study period. In conclusion, the Ribeirão Vermelho is unable to self-purify along its entire length, and water quality is influenced by effluent discharge which intensifies degradation.Keywords: effluent release, Streeter Phelps models, water quality.Coeficiente de desoxigenação, reaeração e potencial de auto purificação de um ribeirão urbano RESUMOOs modelos matemáticos utilizados para simular a qualidade da água e o processo de autodepuração de corpos d'água são importantes ferramentas de auxílio à gestão dos recursos hídricos. Assim, o objetivo deste trabalho foi avaliar o impacto da poluição orgânica na qualidade da água e a capacidade de assimilação da matéria orgânica no Ribeirão Vermelho. Para essa finalidade, foi desenvolvido e testados os coeficientes de desoxigenação (K 1 ) e reaeração (K 2 ), em três trechos e em dois períodos distintos (verão e inverno). Os maiores valores de K 1 e K 2 foram obtidos durante o inverno, onde foram registrados as menores vazões. A simulação do processo de autodepuração foi realizada com o uso do modelo de Streeter-Phelps. A simulação do perfil de OD e DBO no verão apresentou calibração aceitável, tendo em vista a otimização dos coeficientes, evidenciando a prevalência da desoxigenação por demanda carbonácea sobre a nitrificação e a importância da reaeração natural no processo de autodepuração. Comportamento diferente foi observado no inverno, no qual os altos valores de produtividades sobressaíram no processo de reaeração no ribeirão. Apenas o parâmetro demanda bioquímica de oxigênio não respeitou os limites preconizados pela Resolução do Ministério do Meio Ambiente 357/2005, tendo ficado em toda a extensão do rio e, em ambos períodos, fora da regulamentação. Des...

Climate change impact assessment on a tropical river resilience using the Streeter-Phelps dissolved oxygen model

“…For groups 1, 2 and 3, were 0.30 d −1 , 0.36 d −1 respectively. The values obtained for groups 1 and 2 are like those reported for tropical environments, with values of 0.56 ± 0.32 d −1 , with average temperatures of 24 °C and seasonal differences derived from rainfall (Nuruzzaman et al, 2018). The kd obtained for group 3 (0.22 d −1 ), corresponding to January, was the lowest.…”

Development of Non-Point Source Hybrid Cells in Series Model for Reactive Pollutant Transport in Natural Rivers

“…The impulse responses generated for the first, third, seventh and tenth hybrid units with respect to time at different sections of the river from the near field were simulated using Eq. (17) and (19) and is presented as Fig. 2, which shows that all the graphs exhibit a bell-shaped distribution curve with elongated tails.…”

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Impacto ecológico por descargas de aguas residuales hacia el río Mololoa (Nayarit, México) en 12.5 km

“…Cada río tiene su propio mecanismo de autodepuración para cada elemento potencialmente contaminante 180 biodegradable. Para modelar la concentración de OD de un río, es esencial conocer la cinética de DBO, el modelo de Streeter-Phelps utiliza estos dos parámetros para medir la carga contaminante en un río (Nuruzzaman et al, 2018).…”