Wastewater from a fertilizer manufacturing plant in southern Idaho
was pumped into a storage impoundment during the winter months and stored
for irrigating and fertilizing agricultural crops the next summer. Analyses of
water samples from the impoundment taken monthly showed the following
mean annual nutrient concentrations: Total Kjeldahl Nitrogen (TKN) 94,
NH+4-N 61, NO-3–N 8, total P 17, ortho P 15, and K 17 mg/L. The impoundment
surface area averaged 10.5 ha with a maximum pond volume during the
year of 362,000 m3 . Accumulated nutrients in the impounded wastewater
available for irrigating and fertilizing agricultural crops at the beginning of the
growing season was TKN 30.2, NH+4–N 23.2, NO3-N 4.3, total P 9.7, and K 6.2
metric tons. Nitrification in the pond was minimal. Redox potentials were
between 480 and 500 mv at all depths and locations measured in the pond in
the summer and denitrification was minimal. The redox potential indicated that
the water was near oxygen saturation