Towards a methodology for monitoring the deadstock composting process and the resulting gaseous emissions.

摘要

On-farm composting has emerged over the past decade as a viable method for animal mortality (deadstock) disposal. Little is known about the environmental implications associated with deadstock composting, particularly the impact on local air quality. A methodology for characterizing emissions from deadstock composting has been developed. A state of the science compost facility was constructed to conduct full-scale, species-specific, bin compost trials. Emissions were collected by enclosing a bin with a dynamic flux chamber, which supplied a constant flow rate across the pile. Samples were drawn from the exhaust stream of the flux chamber and analyzed for CH4, CO2, NH3, NOx, SO2 and Non-Methane Hydrocarbons (NMHCs) using trace-level gas analyzers. Representative samples were then integrated over the collection period.; A series of tests were conducted to assess the performance of the dynamic flux chamber. Releasing a known concentration of SO2 produced recoveries up to 91.9%. Completely mixed conditions were obtained within 20 minutes after the flux chamber was in operation. Flow sensitivity tests showed that the emission rates increased with increasing flow and suggests a potential convergence to a steady state emission rate, although a larger flow rate is required. Once the optimal air exchange rate is determined the system methodology will allow for the development of species-specific emission factors. These emission factors will assist in (1) creating guidelines and regulations for best management practices, and (2) improving agricultural emission inventories.