SDSU Test Data
The ClearWater BMP

Performance Testing of CLEARWATER SOLUTIONS, Inc.
Storm Water Treatment Prototype "The ClearWater BMP"
November 25, 2003

Mirat Gurol, Ph.D.
Greg Loraine, Ph.D.
Dept. of Civil and Environmental Engineering

San Diego State University Summary A prototype of the CLEARWATER SOLUTIONS, INC. ClearWater BMP storm water retrofit filter was tested at the Environmental Engineering Laboratories at San Diego State University. The prototype was ¼ size of the full unit, but was tested at hydraulic retention times typical of precipitation events in southern California.

Two series of tests were run using two different synthetic storm water. The first tests were run using "Typical" storm water, which exhibited characteristics of real storm water, containing suspended solids in a wide size range, floating oil, and typical concentrations of dissolved metals. The prototype performed very well in these initial tests, so additional tests were done with a "Worst-case" storm water. The "Worst-case" storm water had primarily very fine suspended solids, emulsified oil, dissolved phosphorous, and high concentrations of dissolved and particulate metals. Total Suspended Solids (TSS) removal efficiency was determined at four flow rates. Empirical equations for removal of different size fractions were developed. The removal efficiencies for oil and grease, total phosphorous, copper, lead, and zinc, were measured at two flow rates. The effectiveness of the perlite-zeolite-activated carbon filter (media filter) was also tested.Using the "Typical" storm water calculations at 0.2 inches (3,780 gallons) of rain per hour for an ordinary curb inlet, the ClearWater BMP performed very well. The unit achieved 97% removal of TSS (the EPA standard for Nonpoint Source Pollution in Coastal waters is 80% removal of TSS). Floatable oil and grease was removed with an efficiency of 86% (100% at 16gpm). Zinc was removed at the rate of 83%. Copper came in at 28% (52% at 16gpm). And, lead removal was at 81%. The mixed media filter did not improve TSS removal but did substantially enhance removal of oil and grease, and dissolved metals.

Table 10 compares the removal efficiency of the unit with and without the mixed media filter at flow rates equivalent to 64 gpm in the full size unit. The presence of the filter did not significantly increase TSS removal, even for the small size particles. However, the filter was able to capture emulsified O&G droplets that the oil sock missed. This indicates that adsorption to activated carbon present in the filter is an important removal mechanism for O&G removal. The most dramatic effect of the filter was seen in the removal of dissolved metals. In the "typical" storm water scenario where most of the particle associated metals were attached to fairly large particles, the effectiveness of the filter was not as apparent due to pre-settling. In the "worst-case" storm water scenario, where the metals were either soluble or attached to fine particles, no removal of the metals was achieved without the filter. The filter captured 56% of Zn, 33% Cu, and 14% of Pb. This indicates that the media filter is required to capture any dissolved metals.Table 10: Removal With and Without Mixed Media Filter at 64 gpm. *Click here to contact us for the entire report.

CLEARWATER SOLUTIONS, INC. ClearWater BMP storm water filter Preformance Test
Table 10: Removal With and Without Mixed Media Filter at 64gpm.
  "Typical" % Removal Filtered
"Typical" % Removal No Filter
"Worst-case" % Removal Filtered
"Worst-case" % Removal No Filter