Distribuição espacial do potencial de metano e de impactos ambientais no tratamento dos dejetos da avicultura

Abstract

Poultry waste has little explored potential for energy use and its management in composting generates significant impacts in terms of greenhouse gas (GHG) emissions, ammonia (NH3) and N losses. This study mapped and classified the poultry production systems in Espírito Santo State, Brazil, calculated bird population, manure generation, methane potential in mono- and co-digestion with available co-substrates in the study area, environmental impacts on management. Finally, 2 scenarios (conservative and optimized) were simulated with anaerobic digestion to avoid losses and emissions. In area of study, 2085 production units were mapped, occupying 2242 million m² of area, with 5 production systems, layer hens manure-belt houses (SPaut), layer hens automatic high-house (SPca), layer hens cage house (SPcm), nonacclimatized broiler litter house (SCpn) and acclimatized broiler litter house (SCpp). The population of birds was estimated at 38455 million heads that generate 812684 ton.year-¹ of waste, with a CH4 potential in monodigestion of 76410 thousand m³.year-¹ and a capacity to generate 35.55 MWe. The waste generated from layer manure belt, dry chicken manure and broiler litter, has an emission of 326,104 and 9,862 ton.year-¹ of CO2e of GHG and NH3 and a loss of 25,798 ton.year-¹ of N. The conservative scenario will allow the exploitation energy with the potential to generate 27.23 MW of electricity and the avoidance of 31.8%, 37.2 and 36.4% of GHG emissions, N losses and NH3 emissions, respectively. The optimized scenario will allow the energy use of waste in 226 plants with a total electrical potential of 86.4 MW and avoid GHG and NH3 emissions and N losses by 73.4%, 71.7% and 86.9%, respectively. The unavailability of co-substrates proved to be a limiting factor for the development of alternative scenarios for most co-substrates. The concentration of layer manure belt in SPaut systems is an important factor in GHG and NH3 emissions and N losses in the management of poultry manure, but it is an opportunity to increase environmental efficiency through anaerobic digestion.