Estimativa do potencial de emissão de gases de efeito estufa em diferentes sistemas de tratamento de águas residuárias da suinocultura

• Autor(a) principal: Inoue, Keles Regina Antony
• Data de Publicação: 2013
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/757
• topic: Gases de efeito estufa; Águas residuárias; Suínos; Greenhouse gases; Residuary waters; Pigs; CNPQ::CIENCIAS AGRARIAS::ENGENHARIA AGRICOLA

The aim of this research was to evaluate the potential emission of methane (CH4) and nitrous oxide (N2O), based on the amounts of equivalent carbon dioxide (CO2eq) of residues originated from two pig farms, during a complete cycle, with different residue treatment systems, and to characterize the biofertilizer produced by the anaerobic digestion system of each farm. The study was conducted in a commercial pig unit located in the municipality of Oratórios, Minas Gerais state, Brazil, in the Zona da Mata region, from February 29th to April 11th of 2012. The type of operation adopted in the unit includes total confinement of animals during the Full Cycle (FC), i.e. with all stages of the production cycle of pigs from birth to fattening held within the same facility. The study was conducted in two farms belonging to the same company´s unit. Both had the same architectural characteristics and were handled in a similar manner, with daily cleaning of the barns. The monitoring of emissions from each system was done by analyzes of samples collected on a weekly basis for a total period of seven weeks at the influent and effluent of the digesters. The same procedure was performed in the influent of the stabilization ponds and in each treatment pond. After every collection procedure, the samples were identified and immediately brought back to the Water Quality Laboratory of the Department of Agricultural Engineering (DAE), at the Federal University of Viçosa (FUV), for analysis of the following variables: biochemical oxygen demand (BOD), chemical oxygen demand (COD), total organic carbon (TOC), total nitrogen (N), total phosphorus (P), potassium (K), sodium (Na), total solids (TS), volatile solids (VS), fixed solids (SS), pH and electrical conductivity (EC), to quantify the nutrient concentrations in the influent and effluent of each treatment system. The values of VS and N determined at the influent and effluent were used to calculate the potential emissions of CH4 and N2O, according to the methodology AM0006 "Reduction of emission of greenhouse gases for manure management systems" (UFCCC, 2004) within the Clean Development Mechanism (CDM) established under the Kyoto Protocol. There was a significant difference at 5% probability, with the F test, for the emission of CH4 and N2O between treatments. Methane emissions presented values of 149.25 t CO2eq yr-1 at the digesters and 1120.22 t CO2,eq yr-1 at the stabilization ponds. Mean values for N2O emissions were 53.23 t CO2eq yr-1 and 17 of 50 t CO2eq yr-1 at the digesters and stabilization ponds, respectively. The biofertilizer generated in the process of digestion showed high concentrations of N and K with values of 1481.30 mg L-1 and 661.42 mg L-1, respectively. It is concluded that the greatest potential for CH4 emission was observed in the system of stabilization ponds. As referred to N2O, the opposite occurred, the greatest potential emission was observed at the digester level. The biofertilizer presented high concentration of nutrients, being characterized as a good quality organic fertilizer.