Deoxygenation rate, reaeration and potential for self-purification of small tropical urban stream

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 Streeter-Phelps 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. 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. 749Deoxygenation rate, reaeration and potential for self-purification… Rev. Ambient. Água vol. 10 n. 4 Taubaté -Oct. / Dec. 2015 Palavras-chave: lançamento de efluentes, modelo qualidade de água, Streeter Phelps.

Incertezas sobre a modelagem matemática de qualidade da água em curso de água urbano

“…Entretanto, para este trabalho, o coeficiente de reaeração foi obtido pelo método inverso utilizando da Equação 1, em que ao inserir os dados de entrada e a concentração de oxigênio em um tempo determinado obteve-se o valor de k2 de forma a minimizar a soma dos quadrados dos desvios Menezes et al (2015), ao avaliarem a capacidade autodepurativa do Ribeirão Vermelho, em dois períodos distintos, observaram que a estimativa do k2 por meio da solução da equação proposta por Streeter and Phelps (1958) pelo método inverso enquadrou-se bem com os dados obtidos no campo.…”

Penilaian Daya Tampung Sungai Jangkok dan Sungai Ancar Terhadap Polutan Organik

“…Secara kontekstual, pemurnian secara alamiah (natural self purification) didefinisikan sebagai suatu proses kompleks yang melibatkan proses fisik, kimia, dan biologis yang terjadi secara simultan, yang menggambarkan kemampuan sebuah sungai untuk merecovery status alamiahnya pada jarak tertentu (5,6) . Mekanisme yang terlibat dalam proses self purification antara lain pengenceran (dilution), pengendapan (sedimentation), reaerasi, adsorpsi, absorpsi, rekasi kimia, dan reaksi biologis yang dapat dievaluasi secara matematis.…”

Pre-project geoecological studies for clearing of the Tikhomandritsa riverbed (Tver Region, Russia)

“…According to calculations made by Scientific & Industrial Association Gidrotekhproekt specialists the annual flow of the Tikhomandritsa river in Udomlya lake for dry water years (90 percent exceedance) isregulation of the river flow in dry water years, additional annual water inflow in Udomlya lake is up to 12.5 MCM. This fact also will positively affect the ecological state of the river, because it is known that with increase of flow rate the self-cleaning velocity of rivers rises and their water quality improves [25,26]. Another favorable factor is the aquatic vegetation growth inhibition by increasing the flow and flow velocity.…”