A new concept of carbon dioxide accelerated ammonia release from liquid manure in pig house

Indoor air quality in animal buildings is very important to the health of a gricultural workers and animals. Carbon dioxide (CO2) and ammonia (NH3) are two of the most important pollutants in pig houses. Four tests were conduc ed in a mechanically ventilated pig house to study release behaviors of CO2 and NH3 from liquid manure using impulse, pulse and step ventilation input s. The CO2 and NH3 concentrations were sampled in the exhaust chimney and m easured with a CO2 monitor and a NOx analyzer, respectively. The ventilatio n rate was measured with a ventilation rate sensor in the chimney. A new ph enomenon, characterized by a delayed dynamic response of NH3 release to the high ventilation inputs as compared with the response of CO2 release, was encountered. A new CO2 factor was identified as the cause of the delayed NH 3 response. An original concept of Carbon-dioxide Accelerated Ammonia Relea se (CAAR) was developed. It explained that, at the initial stage of gas rel ease induced by the high ventilation, the high release of CO2 gradually rai sed the pH in the surface manure. The increased pH accelerated the release of NH3. The higher release of NH, had a negative feedback to the pH. The ef fects of CO2 and NH3 releases on the pH Finally reached a dynamic equilibri um. The NH3 release under the dynamic equilibrium was greatly accelerated c ompared to that under initial conditions. (C) 2000 Elsevier Science Ltd. Al l rights reserved.