Gaseous Ammonia Removal Using Biochar.

Biochar has the potential to serve as a sorption medium for removing gaseous pollutants such as ammonia.   Reducing ammonia (NH₃) emissions from livestock facilities is an important issue for many communities and livestock producers.  Ammonia has been regarded as odorous, precursor for particulate matter (PM), and contributed to livestock mortality.  Ammonia sorption capacity of biochars vary due to a difference in feedstock properties, thermal processing conditions, and activation techniques.  In this research, the ammonia sorption capacities of biochars made from pyrolyzing wood shavings and chicken litter at 250 ^oC and 480 to 500 ^oC were determined via sorption column experiments.  Both steam and phosphoric acid activation techniques were employed to activate some of the biochar samples. The bed depth service time (BDST) model was used to calculate the maximum sorption capacities of various biochar samples. Non-activated biochar samples had maximum sorption capacities ranging from 0.15 to 5.1 mg NH₃-N/g biochar. While phosphoric acid activation dramatically increased the sorption capacity up to 53.21 mg NH₃-N/g biochar, steam activation did not improve the sorption capacity.  These biochar samples have compatible sorption capacities to that of commercial activated carbons.