Biological treatment of pulp and paper mill effluents with aerobic granular sludge

• Ano de defesa: 2016
• Autor(a) principal: Morais, Ismarley Lage Horta
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Universidade Federal de Viçosa
• Palavras-chave em Português: Águas residuais - Purificação - Tratamento biológico; Lodo aeróbico granular; Celulose e papel; Tratamento de Águas de Abastecimento e Residuárias
• Link de acesso: http://www.locus.ufv.br/handle/123456789/9372

Aerobic granular sludge wastewater treatment has many advantages over the conventional activated sludge process. The granules are dense and compact microbial aggregates that allow a higher biomass retention in the biological reactor and a high settling velocity, favoring the biological removal of organic matter, nutrients, toxic substances and improves wastewater clarification. Due to the sludge structure and settleability, these benefits have attracted considerable interest in the implementation of the aerobic granular sludge process and givenrise to the need for better understanding of the formation, stability and influence of the operational parameters on the granulation. Thus, this work was divided into three chapters. Chapter 1 presents a review of recent developments on aerobic granular sludge including the possibility of using aerobic granules in membrane bioreactors, at high temperatures and for a full-scale implementation. The addition of divalent cations in the reactors can enhance granulation and granule stability. In Chapter 2, the effect of the addition of 100 mg.L-1 and 200 mg.L- of calcium in the stability, mechanical strength and diameter of the granules formed in sequential batch reactors (SBR) fed with pulp mill effluent was evaluated. The reactors showed similar organic matter removal efficiencies and granule size was approximately 11 mm in all SBR, although the granules formed in the reactor with addition of 100 mg.L- of Ca2+ had a settling velocity 36% higher and greater mechanical resistance than the others. Granulation can also be enhanced by the selection of microorganisms that contribute to the aggregates formation. Bacterial extracellular polymeric substances (EPS) production is one factor that contributes to cell aggregation, since EPS acts as an intercellular cement that may reinforce cohesion inside the bacterial clusters. In Chapter 3, EPS production of nineteen microbial isolates obtained from aerobic granules formed in the recycled paper wastewater treatment was evaluated and six isolates of the genera Staphylococcus, Agrobacterium, Enterobacter and Rhodococcus contributed to biological granulation. The absence of these isolates in the co-aggregation tests reduced the protein-polysaccharide ratio (PN / PS ratio) and reduced the aggregates formation.