Ft. Pierce WWTF - Case study

EXECUTIVE SUMMARY In September of 2014, a CleanB® system was installed at the Ft. Pierce WWTF. Before the CleanB® installation, the plant wasted to a DAF unit for thickening and held sludge in an aerobic holding tank prior to contract dewatering and landfill disposition. After installation of the CleanB® system, the plant started wasting directly from the clarifier to the CleanB® unit and centrifuge dewatering.

The following chart illustrates the timing of sample collections and CleanB® installation. Differences in nutrients leaving the clarifier were noted and were attributed to the timing of the samples. The capture rates of solids and nutrients after installation of the CleanB® show a substantial improvement when compared to the previous practice. Percent capture of Nitrogen went from 25.9% with DAF thickening and aerobic holding to 92.9% with CleanB® treatment. Percent capture of Phosphorous went from 21.1% to 83.1% with CleanB® treatment.

The key conclusions from this work effort are:

1. Solids return via filtrate was reduced by 70% (76 tons/year)
2. Total Nitrogen return via filtrate was reduced by 92% (45 tons/year)
3. Total Phosphorous return via filtrate was reduced by 66% (9 tons/year)
4. %TS on dewatered biosolids improved by 21% (52 less Truckloads/year)
5. Total polymer consumption was reduced by 34% (reduction of 26.8 lbs/DT)
6. Total Nitrogen leaving with the biosolids was increased by 182% (35 tons/year)
7. Total Phosphorous leaving with the biosolids was increased by 476% (20 tons/year)
8. A $57k per annum expense from the aerobic holding tank blowers were taken off-line
9. Energy/GHG emission savings equates to 50.8 cars per year or 86.4 tons of waste sent to the landfill

In addition to the advantages of higher capture rates and reductions in greenhouse gas (GHG) emissions, it is estimated that Ft. Pierce WWTF will now realize a $242,000 savings per year in operating cost using the CleanB® vs. their original aerobic holding processing. Below is a summary of the net impact to operations utilizing the CleanB® as compared to aerobic holding at Ft. Pierce: