A meus pais, Milton e Clélia, por toda a dedicação para a minha formação e a minha esposa Alessandra pelo apoio e compreensão nos momentos de ausência. AGRADECIMENTOS Agradeço primeiramente ao professor Eduardo Cleto Pires, pela orientação, compreensão, incentivo e confiança durante esse trabalho. A empresa Tecumseh do Brasil Ltda., pelo programa de incentivo ao desenvolvimento profissional de seus funcionários em especial ao gerente da Engenharia Industrial Avançada, Sr. Ivan Dias, pela

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... idade e compreensão na realização desse trabalho e ao gerente da Unidade de Serviços, Sr. Maurício T. S. Silva, por possibilitar o acesso a ETE da empresa e a realização desse estudo. Ao professor Marco Antonio Penalva Reali, por toda colaboração e paciência durante toda a pós-graduação e pela autorização para acesso ao LATAR e utilização dos equipamentos e materiais envolvidos nesse trabalho. Ao Daniel e os seus funcionários, Jair e Edes, pelas informações fornecidas da ETE, colaboração nas etapas iniciais desse trabalho e na coleta de amostras. À Maria Teresa, técnica do LATAR, pelo auxílio na realização de todos os ensaios desse trabalho e pela paciência em relação aos meus horários. Aos professores Marco Antonio Penalva Reali e Marcelo Zaiat pelas valiosas sugestões no exame de qualificação. Ao Alcino, funcionário da USP, pelo apoio na manutenção de alguns equipamentos. A empresa Procytek Indústria e Comércio Ltda. pela colaboração técnica e fornecimento de amostras. As funcionárias do Departamento de Hidráulica e Saneamento, Sá, Pavi e Rose. A todos meus familiares e amigos pela amizade e apoio. Palavras chave: esgoto industrial; água residuária industrial; coagulação; precipitação; sedimentação; flotação; aluminato de sódio; cloreto férrico; policloreto de alumínio. ABSTRACT LOPES, M. A. Evaluation of different coagulants for solids removal by flotation and sedimentation of wastewater from a metal-mechanic industry. 2011. p. Dissertation (Mestrado). Department of Hydraulics and Sanitation. Engineering School of São Carlos. Universidade de São Paulo. 192p. São Carlos, SP. One approach to minimize the consumption of drinking water and effluent disposal is the reuse of water within the plant through advanced treatment techniques such as reverse osmosis system, however, this system requires an affluent with a low amount of solids and other requirements. The wastewater used in this study comes from a metalworking company that uses coagulation-flocculation-sedimentation process as a way to remove the solids before a reverse osmosis system. The purpose of this study was to evaluate three different coagulants (sodium aluminate, ferric chloride and a mixture of two commercial coagulants, Procytrat 100A and Procytrat 300) in the process of coagulation-flocculation and separation of solids from the liquid phase by sedimentation and dissolved air flotation and also compare the approximate costs of the processes involved. Jar tests and flotatests were performed and the coagulation-flocculation diagrams were built. In the coagulation-flocculation diagrams were selected areas of higher solids removal. Through the chosen regions, comparisons were made of removal efficiency and cost study for each coagulant. It was found that the diagrams of coagulation-flocculation-sedimentation presented the areas of higher turbidity remaining area with less than 2%, mainly for the coagulants ferric chloride and the mixture Procytrat 100A + Procytrat 300, reaching values close to 0.5 %. The most economical option was achieved at a cost of ferric chloride at a dosage of 200mg/l, pH 8.3, and the remaining turbidity equal to 0.6%, from R$ 0.47/m3 treated water. The diagrams of coagulation-flocculation-flotation showed regions with turbidity remaining areas much reduced compared to the diagrams of coagulation-flocculation-sedimentation, and the turbidity remaining values were more than 1.5%. The lower values of turbidity remaining for the flotation process were found using the mixture Procytrat 100A + Procytrat 300, and the most economical option was reached for a pH of 3.3, dosage of 60mg/l and remaining turbidity equal to e 1.6%, at a cost of R$ 0.33/m3 of treated water. In general, for all coagulants tested, the selected regions in the diagrams of coagulation-flocculation-flotation, whose remaining turbidity values were lower, were concentrated in low pH values (3.2 to 5.5), dosages of coagulant reduced (10 to 80mg/l) and dosages of alkaline also reduced (0 to 60mg/l of Ca(OH) 2 ). This behavior was contrary to the diagrams presented by coagulation-flocculation-sedimentation whose remaining turbidity values were lower in higher pH values (6.5 to 8.5), larger amounts of coagulant (40 to 380mg/l) and high doses of alkaline (100 to 400mg/l Ca(OH) 2 ).