Odor Control for Animal
Housing Systems with Dry Manure - Filtration and Biofiltration
| Pro |
Con |
| Traps multiple gases and odor |
Needs good maintenance to operate properly |
| Versatile for mechanically ventilated operations |
Potential to have a limited life of effectiveness |
Some odors travel attached to particles.
By effectively trapping particle emissions, odorous compounds
can also be trapped. Mechanical filtration traps approximately
45 percent of particles between 5 and 10 µm and 80 percent of particles greater than 10µm
from animal housing areas. Mechanical filtration reduces the odor
dilution threshold by 40-70 percent.
Biofilters trap particulates and also provide an environment for
biological degradation of the trapped compounds. Biofilters have
been developed to reduce odorous emissions from deep-pit, manure
ventilation exhaust. Although mechanical filtration may be costly,
biofiltration methods can inexpensively and effectively reduce
exhaust odors. Biofiltration costs for a 700-head farrow-to-wean
swine facility are estimated at $0.25 per piglet, amortized over
a 3-year life of the biofilter. Odor reductions at the facility
exceeded 90 percent with similar reductions in hydrogen sulfide
(90 percent) and ammonia emissions (74 percent). Similar odor and
hydrogen sulfide reductions were observed using biofiltration on
a dairy facility. The dust generated in a poultry facility, however,
led to a poorer biofilter performance, with odor and hydrogen sulfide
reductions of less than 40 percent.
Biofilters must be designed to provide suitable conditions for the
growth of a mixture of aerobic bacteria within the biofilter. These
bacteria will degrade the odorous compounds into less odorous end
products. Oxygen concentration, temperature, residence time, and
moisture content are among the parameters that must be considered
when building a biofilter. Although management must be taken into
consideration, it is clear that low-cost biofiltration systems ($150-200
per 1,000 cfm of air treated) can be implemented in livestock housing
facilities.
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