Evaluation By: North Carolina State University Biological and Agricultural Engineering Laboratory and North Carolina Department of Agriculture
Treatment was initiated September 23, 1996. Between September 23, 1996 and February 3, 1997, the mean sludge depth decreased from an average depth of 3.5 feet (range 2 to 5.5 feet) to an average depth of 2.1 feet (range 1 to 3 feet). The sludge depth decreased further to approximately 1.5 feet by March 17th and to 1.22 feet (range 0.75 to 1.5 feet) by May 5th. The concentrations of the micronutrients (copper and zinc) in the lagoon liquid remained fairly steady except for the spike that occurred in both the March 17, 1997 and March 18, 1996 samples. The concentration spikes may indicate seasonal turnover within the lagoon.
Some of the conclusions from this project are as follows:
- The added bacteria appear to be quite effective at sludge reduction. The product may be useful in both sludge level maintenance and lagoon closure situations.
- More information is required to make a decision on the use of the product for odor
- Changes in nutrient concentrations in the liquid fraction during sludge reduction appear
to be minor for most of the nutrients of concern.
- Changes in nitrogen (lb/1,000 gal) can be monitored by the farmer through NCDA
analyses. Adjustments in land application amounts can then be made.
- No significant changes in the percentage of solids were observed in the lagoon liquid;
therefore, the treatment should not increase any adverse effects on irrigation