Eficiência do sistema de aeração em cascata no tratamento da água residuária da lavagem e descascamento/despolpa dos frutos do cafeeiro

• Ano de defesa: 2010
• Autor(a) principal: Eustáquio Júnior, Valdeir
• Orientador(a): Matos, Antonio Teixeira de
• Banca de defesa: Silva, Juarez de Souza e , Magalhães, Marcos Alves de , Donzeles, Sergio Mauricio Lopes
• 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 Agrícola
• Departamento: Construções rurais e ambiência; Energia na agricultura; Mecanização agrícola; Processamento de produ
• País: BR
• Palavras-chave em Português: Tratamento biológico; Oxidação; Resíduos orgânicos
• Palavras-chave em Inglês: Biological treatment; Oxidation; Organic waste
• Área do conhecimento CNPq: CNPQ::CIENCIAS AGRARIAS::ENGENHARIA AGRICOLA
• Link de acesso: http://locus.ufv.br/handle/123456789/3577

Due to lack of technical information on the treatment of wastewater using cascade aeration systems, this work aimed to study the performance of this system in the treatment of the wastewater from washing and stripping/pulping coffee (CW). In addition, it sought to determine the coefficient of efficiency associated with cascade aeration system, evaluate the incorporation of dissolved oxygen and the system s ability to remove organic matter, nutrients (nitrogen, phosphorus and potassium) and phenolic compounds from CW. The experiment was assembled and conducted in the Waste Management Experimental Area of the Agricultural Engineering from the Federal University of Viçosa. The cascade aeration system was installed in a slope with an inclination of 30° and with a level difference of 4.14 m. The cascade consisted of 23 steps, with height, width and length of 0.18; 0.32 and 0.60 m respectively. At the end of the cascade was installed a container with 2 m³ volume. It was called reception/detention of the CW disposed on the ladder. After a detention time of 3 hours, the CW was transferred to another tank, called recirculation tank, where it was pumped for further recycling in the cascade. This recirculation was done three times a day and under constant flow rate of 1 L s-1. During the 30 days of operation of the treatment system it was used samples of CW collected at three different occasions and it was changed every 10 days of system. The experiment was conducted following a randomized block design, split plot in time, consisting of 3 blocks (3 samples CW). Regarding to the variable BOD, it was evaluated six main treatments (location in the cascade of CW) and four secondary treatments (recirculation time of CW: 0, 3, 6 and 9 days), totalizing 72 experimental units. As regards the analysis of changes in variable COD, it was evaluated six main treatments (location in the cascade of CW) and 10 secondary treatments (recirculation time: 0, 1, 2, 3, 4, 5, 6, 7, 8 and 9 days), totaling 180 experimental units. In this case, the experimental units were composed of samples collected each day, in pre-set points. To study the decay of dissolved oxygen concentration versus time in the receiving/holding tank , another experiment was conducted in a randomized design with 6 replications and 15 treatments (0, 2, 4, 6, 8, 10, 12 , 14, 16, 18, 20, 22, 24, 26, 28 minutes). In this evaluation, the experimental units were the rates of CW sampled every 2 minutes. With the cascade aeration system it was possible to incorporate an average of 0.2 mg L-1 of oxygen at each meter of stairs. The maximum percentage of oxygen saturation in the CW was 19.4% and it was obtained at flight of stairs at 4 m. The high concentration of organic material did not allow it to detect major changes in the concentration of dissolved oxygen in the CW. The system consisting of cascade aeration coefficient for efficiency of 0.078. The detention time in the tank for ideal reception/detention was 26 minutes. The system in operation provided average removal efficiency of COD was 28.9%. The removals of total solids, volatile solids, total suspended solids, volatile suspended solids, total nitrogen, total phosphorus, potassium and total phenolic compounds were 57.3; 71.6; 26.5; 17.2; 35.7; 62.5; 49.5 and 55.0% respectively. The cascade aeration proved to be an important alternative for the composition of treatment systems of CW, considering it is a very effective aerobic treatment of suspended organic material.