2. Development of BMP Cost-Effectiveness Values
Cost-Effectiveness of Land Application Relative to Direct Discharge
96 kg TKN /head-year
0.027 to 0.11 ha
25 kg TKN
liquid + sludge
0.46 kg TKN /head-year
0.085 to 0.35 ha
0.10 kg TKN
From Table 2-6.
From Table 2-2.
These figures cover the range of agronomic rates for land application. From Zublena et al.
Zublena et al.
Anaerobic lagoons account for 43 percent of the cost-share money expended on
animal waste management in the Tar-Pamlico basin. Lagoons use bacteria to
convert an animal waste slurry into a liquid that can be spread onto the land as
fertilizer or used as flush water for a recycle cleaning system. in an anaerobic
lagoon, facultative and anaerobic bacteria degrade organic matter, producing
organic acids, methane, and carbon dioxide (Merker, 1981). The process can
greatly decrease the BOD, total and volatile solids, and nutrient concentration in
the effluent. in the Tar-Pamlico basin, anaerobic lagoons are primarily used to
treat swine and poultry (layer) waste (NCDSWC, 1994).
It is important to note that lagoons are only one part of an effective animal waste
as the Tar-Pamlico basin),
management system. In
lagoons will overflow unless they
pumped out (Humenik et al., 1980).
Although lagoons can be highly effective in reducing nutrient concentrations, the
effluent nutrient concentrations are still very high and must be applied to growing
crops at agronomic rates. In the Tar-Pamlico basin, anaerobic lagoons play an
important role because farms often have limited land area suitable for waste
application. Lagoons decrease the nutrient load in the waste, effectively
decreasing the area required for land application. This, in turn, allows the farmer
to raise greater numbers of animals. Table 2-8 presents the cost data for
anaerobic lagoons in the Tar-Pamlico basin.