Desinfecção solar de esgoto doméstico para uso na agricultura familiar

• Autor(a) principal: Román, Rodrigo Máximo Sánchez
• Data de Publicação: 2006
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/662
• topic: Esgotos; Desinfecção solar; Águas residuais; Purificação; Domestic wastewater; Solar disinfection; Purification; CNPQ::CIENCIAS AGRARIAS::ENGENHARIA AGRICOLA::ENGENHARIA DE AGUA E SOLO

A pilot study to disinfect domestic wastewater using solar radiation was built in the Experimental Station for Domestic Wastewater Treatment for Use in Agriculture (ESDWT-UA) of the Departamento de Engenharia Agrícola at Universidade Federal de Viçosa, Minas Gerais, Brazil. The experimental station is located at 20º45'14" S, 42º52'53" W, altitude 648.74 meters above sea level (masl). The effluent from a residential development was used as supply; this treated domestic wastewater (TDWW) passed through a pretreatment unit, and primary treatment in septic tank with detention time of 14 hours. After that, in the solar reactor, the septic tank s effluent was exposed to solar radiation for eight hours in a batch system treatment. Samples of water were collected every two hours. The samples were analyzed for: dissolved oxygen, turbidity, chemical oxygen demand (COD), total suspended solids (TSS), total coliforms and Escherichia coli (E. coli). Water temperature in the solar reactor was taken every hour. An automatic meteorological station, installed at ESDWT-UA, was used to collect solar radiation data. All data were statistically analyzed, and a model was proposed to estimate the final E. coli population given the initial E. coli population in the TDWW, the TDWW depth to be treated at the solar reactor and the dose accumulated. Using the model proposed in this work, and the insolation values for 202 meteorological stations distributed throughout Brazil, the time of exposure necessary to disinfect the TDWW was determined reducing the E. coli population to values recommended by World Health Organization (WHO) for irrigation water to be used without any sanitary restriction in agriculture. 48 maps with the exposure times for monthly distribution were elaborated for four depths (0.05, 0.10, 0.15, 0.20 m) of TDWW to be used in Brazil. The financial viability of this project was evaluated considering a family of four people. The analysis considering: the initial investment, costs (maintenance, seeds, implements, debt payments, etc.), and incomes generated by the production of food in the family vegetable garden. It was found that the present value (VPL), the capital rate of return (TRC), internal rate of return (TIR) and cost/benefit (C/B) relationship were all favorable to the implantation of the project when Programa Nacional de Fortalecimento da Agricultura Familiar Mulher PRONAF - Mulher), for four scenarios analyzed was considered as source of financing.