A group of scientists from the Agricultural Research Service (ARS) in the U.S. Department of Agriculture and Filtrexx International of Grafton, Ohio, have improved on the methods for removing contaminants from storm water runoff. The runoff from storm water is particularly vulnerable to pollution in industrial areas or near construction sites.
Current methods use “filter socks” containing compost tucked into mesh tubes that capture some of the silt, heavy metals, fertilizers and petroleum products that wash from compacted surface areas into nearby streams and rivers. The team from ARS and Filtrexx tested if adding flocculation agents to the filers — a practice of some waste water treatment plants — would help sediments and pollutants form clumps large enough to be filtered out of the water.
The team found that compost socks alone removed most of the clay and silt particles that making up suspended solids in surface waters. However, socks with the added flocculation agents removed even more of the pollutants from runoff, The differences were most notable with petroleum products, where runoff levels of diesel fuel dropped 99 percent, levels of motor oil dropped 84 percent, and gasoline levels dropped 43 percent.
Filtrexx researches and manufactures organic and bio-based technologies used in storm water and land improvement systems.
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