Indigo — Pilot Test Results
A wastewater treatment facility in Mount Holly, North Carolina (additional information available upon request) used the Indigo formula (formerly known as Bio-Booster™) during February and March of 2002. During that time the facility improved plant efficiency, removed lime stabilization and cut their hauling costs in half.
The information contained below provides a high-level overview of the facility and how they cut the normal process to thicken and prepare the biosolids for land application. The following is an outline of the facility’s treatment process prior to using the Indigo formula.
• Waste biosolids to an aerobic digester (2 - 750,000 gallon tanks).
• Biosolids are thickened as much as possible, usually to 2.8% to 3% solids and
the clear water is decanted.
• Sludge is then transferred to tank # 1 where sludge is stored until the tank is
full.
• When tank # 1 is full, the biosolids are lime stabilized to meet the 503 requirements for land application.
With the Indigo formula test, the same process was followed, thickened and decanted in tank and then transferred to tank # 1. The first application which occurred on 02-11-2002, consisted of 20 gallons of the Indigo formula added to 475,620 gallons of biosolids in tank # 1, followed by another 7.5 gallons of the Indigo formula added on 02-17-2002. The results are as follows:
Summary: 750,002 gallons of biosolids were added to the 475,620 gallons of biosolids in tank # 1 on 2-11-02 creating a sum of 1,225,622 gallons of biosolids treated with Indigo formula. The facility no longer needs to use lime stabilization to meet the 503 requirements because the Indigo formula generated a 95.9% reduction in volatile solids.
Cost Savings:
Dry Tons Before Indigo formula - 1,225,622 gallons of biosolids at 3.08% solids =
143.1 Dry Tons
Dry Tons After Indigo formula - 559,743 gallons of biosolids at 3.08% solids =
71.89 Dry Tons
*This savings and drop in dry tons was achieved over a 2 month period.