Avaliação da eficiência da ozonização combinada com o tratamento por lodos ativados de efluentes de fábricas de celulose kraft branqueada

• Ano de defesa: 2009
• Autor(a) principal: Silveira, Daniella Sette Abrantes
• Orientador(a): Mounteer, Ann Honor
• Banca de defesa: Rezende, Ana Augusta Passos , Passos, Frederico José Vieira
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Viçosa
• Programa de Pós-Graduação: Mestrado em Engenharia Civil
• Departamento: Geotecnia; Saneamento ambiental
• País: BR
• Palavras-chave em Português: Águas residuárias; Tratamento biológico; Compostos recalcitrantes; Toxicidade
• Palavras-chave em Inglês: Wastewater; Biological treatment; Recalcitrant compounds; Toxicity
• Área do conhecimento CNPq: CNPQ::ENGENHARIAS::ENGENHARIA SANITARIA::TRATAMENTO DE AGUAS DE ABASTECIMENTO E RESIDUARIAS
• Link de acesso: http://locus.ufv.br/handle/123456789/3715

The pulp industry consumes large quantities of water and is consequently responsible for generating relatively large volumes of effluents, that if not adequately treated can cause serious harm to receiving waters since they are rich in organic matter and recalcitrant compounds. The objective of the present study was to evaluate the efficiency of ozone as pre, intermediary or post-secondary treatment, aimed at removing organic matter in bleached kraft pulp effluents. Three types of effluents were collected (primary, partially biologically treated, or intermediate and secondary) from a Brazilian bleached kraft pulp mill. These effluents were treated with ozone at doses of 50 to 1000 mgO3 L-1 and temperature of 35ºC. The effluents were characterized before and after treatments by quantifying: pH, TOC, lignin, COD, BOD5, color, carbohydrates and AOX. Two ozone flow rates, 5 and 50 mgO3 min-1, were tested in treatment of the primary effluent, while the other effluents were treated at the lower flow rate only. Ozonation of primary effluent resulted in a decrease in biodegradability, and is thus not indicated for this effluent. Ozonation of secondary effluent was efficient in reducing effluent COD, TOC, color and lignin. Application of ozone to intermediate effluent resulted in an increase in biodegradability as well as reductions in lignin and color. Combined biological + O3 (50 mgO3/L) + biological treatment reached higher removal efficiencies than obtained in the mill biological treatment system for all parameters evaluated except BOD and color, which presented equal efficiencies. Ozone treatment reduced the high molar mass fraction of organic matter, transforming it into low molecular mass compounds that can be more easily biodegraded. None of the three effluents, before or after ozonation, presented toxicity to the micro-crustacean Daphnia similis. Primary and intermediate effluents presented chronic toxicity in the form of growth inhibition to the green algae Pseudokirchneriella subcapitata, whereas secondary effluent stimulated growth of this test organism. Ozone treatment reduced the chronic toxicity of the intermediate effluent as well as the stimulatory effect of the secondary effluent. Biological treatment eliminated the inhibitory effect and actually led to a stimulatory effect of the intermediate effluent treated with 50 mgO3 L-1.