Agricultural
Engineering News, Issues, and Research - Dairy and
Livestock Wastes I
- Dana O. Porter
- Agricultural Engineering Specialist
- WVU Extension Service
The following summaries are compiled from recent
publications, research articles, and/or presented papers.
They are intended to inform readers of agricultural
engineering developments and related issues of interest
to West Virginians. These brief summaries are not
comprehensive; they do not represent all data, results,
and conclusions of the articles. Readers should obtain
the complete publications for more information. While the
sources are considered reliable, use caution when
applying this information.
Solids and Nutrient Removal by Sedimentation from
Dairy Wastewaters
Municipal and industrial wastewater treatment plants
use chemical flocculants and solids separation to remove
nutrients and organic matter from wastewaters. The
potential of chemical flocculants and sedimentation to
remove nutrients and organic particulate matter from
manure flushwaters was investigated in a bench scale
study conducted by Barrow, et al., (1997).
According to the study, sedimentation potentially can
remove more solids and nutrients from manure flushwaters
than screening. The use of flocculants (such as ferric
chloride) to precipitate minerals (such as phosphorus)
from dairy manure wastewaters appears to be a promising
technology for farms needing to export fertilizer
nutrients off-farm.
Barrow, J.T., H.H. Van Horn, D.L. Anderson, and
R.A. Nordstedt. 1997.
Effects of Fe and Ca additions to dairy wastewater on
solids and nutrient
removal by sedimentation. Applied Engineering in
Agriculture 13(2):259-267.
Aeration to Control Odor in Liquid and Slurry
Livestock Wastes
Sources of odors generated in livestock production
operations include production facilities, waste treatment
systems, and land application. Aerobic (oxygen available)
treatment of animal manure slurry and lagoon liquid can
be effective for odor control. However, the high energy
requirements (and associated costs) for aeration limit
use of aerobic treatment systems in livestock manure
management. Recent research has been directed toward (1)
developing more efficient aeration techniques and
equipment, (2) determining minimum aeration requirements
for odor control, and (3) developing optimum intermittent
aeration schemes to obtain efficient manure decomposition
and to effect nitrogen transformation and removal.
Since complete stabilization of livestock manure by
aerobic treatment normally is not economically feasible,
lower levels of aeration (1/3 to 1/2 daily BOD* loading
for partial odor control vs. twice the daily BOD loading
for aerobic stabilization) have been recommended for
partial odor control (Westerman and Zhang, 1997).
Mechanical aeration for odor control can be confined to
the upper layer of the lagoon, thereby reducing surface
area required for oxygen diffusion and energy required
for aeration.
Aeration for odor control also affects volatilization
of ammonia and nitrogen transformations. Intermittent
aeration schemes involving sequencing of aerobic and
anoxic conditions have been applied to achieve high
removal of convertible nitrogen in wastes (Westerman and
Zhang, 1997).
* Biological Oxygen Demand
Westerman, P.W. and R.H. Zhang. 1997. Aeration of
livestock manure
slurry and lagoon liquid for odor control: a review. Applied
Engineering
in Agriculture 13(2):245-249.
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