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.