Avalia??o do ?ndice de qualidade da ?gua no Ribeir?o Capim, M?dio Rio Doce ? Governador Valadares, MG.

A bacia do Rio Doce, quinta maior do estado de Minas Gerais, mostra-se bastante degradada com impactos diretos na vegeta??o, no solo, na biodiversidade e na qualidade das ?guas. Sabendo-se da import?ncia da bacia em quest?o executou-se um estudo no Ribeir?o Capim, afluente do Rio Doce, este influenciado diretamente por uma ind?stria de papeis reciclados e o efluente de um esgoto urbano de um bairro da cidade de Governador Valadares, MG. Foi realizada uma completa caracteriza??o f?sico-qu?mica e microbiol?gica ao longo do Ribeir?o em estudo e determinado o ?ndice de Qualidade da ?gua, desenvolvido pela National Sanitation Foundation dos Estados Unidos, para seis esta??es de coleta. Ainda, atrav?s de metodologias especificas, procurou-se avaliar a real interfer?ncia do esgoto fabril no corpo h?drico em quest?o, bem como a proposi??o de medidas corretivas ao processo de tratamento de efluente industrial. Verificou-se que tanto o esgoto gerado pelo bairro como o efluente decorrente da atividade industrial, s?o os grandes respons?veis pela polui??o do Ribeir?o Capim. Esta conclus?o se estabeleceu ap?s compara??o dos resultados do ?ndice de Qualidade da ?gua obtido no ponto amostral 1, situado pr? impactos antr?picos, com os demais ambientes de coleta. Em rela??o ? efici?ncia do processo de tratamento do efluente industrial, este atendeu as normas dos padr?es de lan?amento estabelecidas pelas resolu??es vigentes, porem necessita-se de um melhor acompanhamento na carga de DBO lan?ada no Ribeir?o, estando esta perto dos limites de padr?o de lan?amento.The Rio Doce river is the fifth largest watershed of Minas Gerais state, and it shows many signs of degradation, which directly impacts its vegetation, soil, biodiversity and water quality. Due to the importance of Rio Doce watershed, this study focused on one of its tributaries, the Capim water stream. It was found that the water quality of Capim stream was directly affected by a pulp and paper industry as well as by the sewage produced by a neighborhood of Governador Valadares city. This study accomplished a complete physical-chemical and microbial characterization along the Capim stream, and the results were used to determine, for six collecting spots, the Water Quality Index (WQI) according to the procedures adopted by the United States National Sanitation Foundation. In addition to that, this study used specific methodologies to evaluate the real interference of the industrial wastewater to the water quality of Capim stream; and also proposed corrective actions to the industrial wastewater treatment plant. It was found that both urban sewage and industrial wastewater are the main agents responsible for the pollution of Capim stream. This conclusion could be drawn after comparing the results of WQI calculated for collecting point 1, which was located upstream the discharge of sewage and industrial effluent, with WQI values from the other collecting points. The results of this study showed that the wastewater treatment plant met the environmental standards set by the Brazilian legislation, however, the biochemical oxygen demand (BOD) measured in Industrial effluent was close to the imposed discharge limits. Therefore further studies are needed to follow the impact of the BOD load to the Capim water stream