Quantification of Ammonia and Hydrogen Sulfide Production from Poultry Litter

Abstract

In response to environmental and occupational health concerns, many poultry operations treat the litter in their animal buildings with chemicals that decrease its pH, and therefore decrease ammonia (NH3) gas production. However, the possible increase in hydrogen sulfide (H2S) production that may result from a decreased pH has not been adequately studied. An in-lab apparatus was developed to measure the effect of pH and volumetric water content (VWC) changes on the production of NH3 and H2S production from chicken litter. An NH3 analyzer and H2S sensor were used to monitor gas concentrations. The litter was gathered from one of the poultry buildings at the Stephen F. Austin State University (SFASU) Poultry Research Center in Nacogdoches, Texas and had been reused for six flocks over the course of the year. Litter pH was altered using sodium bisulfate. Three pH levels (6.0, 7.0, and 8.0) and three moisture levels (20, 30, and 40%) were tested. The experiment determined that there was no significant difference in NH3 or H2S production between the three pH treatments and no significant difference in H2S production between the three VWC treatments. However, significantly higher concentrations of NH3 were produced in the 40% VWC treatments than in the 20% VWC treatments. Additionally, NH3 production without the sodium bisulfate treatment approached OSHA TWA ceiling levels (22 ppm) in some tests, but were always far below the OSHA requirements once treated, regardless of the pH level. H2S production never approached the OSHA 8-hour TWA of 10 ppm.