Comparison between two systems for ammonia emission monitoring in broiler houses

This work aimed to compare two systems used for ammonia emission monitoring in broiler houses. The low cost PMU (Portable Monitoring Unit), and MAEMU (Mobile Air Emission Monitoring Unit) are systems used for ammonia concentration monitoring and, with broiler house ventilation rate, ammonia emission rate (ER) can be calculated. The accuracy of ammonia emission rate calculated with data from the PMU using a simplified calculation algorithm was quantified using the MAEMU as a standard. Four PMU monitors were randomly assigned to three locations in two different commercial broiler houses in which simultaneous MAEMU measurements were being conduced as part of a year-long ammonia emissions project. Hourly ER was estimated for each PMU by multiplying three average concentration recordings per hour by the mean ventilation rate recorded by the MAEMU system. The MAEMU system obtained more frequent ER measurements (six to thirty measurements per location per hour). Mean (±standard deviation) difference in hourly NH₃ concentration for the entire experiment was 3.8 (±2.4) ppm_ν, slightly more than the 3 ppm _ν uncertainty in the EC sensors according to specifications. Mean difference in hourly ER was 0.053 (±0.048) g NH₃ h ^-1 for VR < 32,000 m³h^-1, and 0.351 (±0.295) g NH₃ h^-1 for VR > 45,000 m ³h^-1, with overall mean difference in hourly ER 0.133 (±0.062) g NH₃ h^-1. Results suggest the proposed (simplified) PMU method results in an over-prediction of ER, with greater bias for larger values of VR. The simplified calculation procedure is suitable for ER if appropriate adjustments are made as described.