NITROGEN TRANSFORMATIONS AND REDUCTION BY RIDGE
AND FURROW LAND TREATMENT OF DAIRY WASTE
Fred J. Doran, Engineer
Foth and Van Dyke Industrial, Inc.
Green Bay, Wisconsin 54307
David K. Sauer, Engineer
Wisconsin Department of Natural Resources
Madison, Wisconsin 53702
William C. Boyle, Professor
P. Mac Berthouex, Professor
Department of Civil and Environmental Engineering
University of Wisconsin-Madison
Madison, Wisconsin 53706
INTRODUCTION
For many years the ridge and furrow land treatment process has been a popular and simple method
of industrial wastewater disposal. In Wisconsin, there are 83 dairies, four meat packers, a rendering
plant, and a pet food manufacturer which use ridge and furrow treatment [1]. Site areas range from
0.1 to 56 acres. The three advantages in selecting this treatment process are: 1) ease of operation; 2)
low capital and operation/maintenance costs; and 3) year around operation [1]. Design is based on
hydraulic and BOD, loading rates. Nitrogen loading rates have generally not been considered in the
past. Two or more cells are preferred to allow for load/rest flexibility. Load/rest cycles alternately
aerate and deaerate the soil which enhances wastewater treatment [2,3,4,5].
This paper presents the results of a study supported by the Wisconsin Department of Natural
Resources (WDNR) and conducted at two ridge and furrow sites treating cheese processing wastewater. Site A receives 39,000 gallons per day (gpd) and is located on 4.7 acres of sandy soil. Site B
receives 14,000 gpd and is located on 3.0 acres of silty loam soil.
The project had the following three objectives: 1) to calculate a nitrogen budget for the unsaturated zone beneath each system; 2) to determine the nitrogen transformations in the wastewater as
it percolated from the furrow to the groundwater; and 3) to analyze ridge and furrow treatment
effectiveness under different soil and loading conditions.
To complete these objectives, groundwater monitoring wells and lysimeters were installed and a
sampling program was initiated in August 1983. Well, lysimeter, furrow-water, and wastewater samples were collected and analyzed through November 1984.
SITES, MATERIALS, AND METHODS
Site A is located on an unconfined aquifer consisting of glacial outwash along the Sugar River.
This sandy material extends approximately 70 feet deep and overlays a sandstone aquifer. Results of
soil analyses conducted on samples collected during well and lysimeter installation at Site A indicated
the following parameter ranges:
• sand: 81-99%,
• silt: 0-16%,
• clay: 1-5%,
• average CEC: 3 meq/100 grams soil, and
• total nitrogen: 0-0.11%
A plan view of the 4.7 acre, two cell system is shown in Figure 1.
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