275 BioDOWN Biofilter

System Details

The Gullywasher 275 BioDOWN Biofilter is a passive stormwater purification filter able to remove metals and other contaminants from stormwater.

The main Filter Box container is a repurposed 275-gallon chemical tote, only used once and solely with compatible chemicals for stormwater. A 12-gallon filter box with a 10 oz geotextile Filter Bag is used for separating incoming large suspended solids from stormwater.

Filtered stormwater gravity flows out of the filter box and into two Influent Launders– one on either side of the filter box. These allow for equal distribution of the stormwater onto the grated filter screen.

The first media level is a filter screen consisting of Gullywasher's Filter Grade Quartz Sand. This is properly sized and rinsed quartz (non-metal content) sand media that allows for depth filtration and sufficient porosity.

The second media level is a filter screen consisting of Gullywasher's Biochar Mix 2 Media. This is an engineered filter media designed to remove metals (dissolved & total), BOD and COD. This media also has a minor ability in removing nutrients.

The final filter screen media is our Filter Grade Quartz Gravel. This is a filter-grade gravel with specified round corners and quartz (non-metal) content.

Once the stormwater flows out of the filter box outlet, it flows up through an effluent discharge outlet piping before exiting. This forces the stormwater from entirely flowing from a gravity push to that of a partial mass balance displacement. This provides the stormwater ample time to have the treatment dynamic contacts necessary to maximize metals removal.

We can utilize virtually any filter media; however, the lab test results are focused solely on the use of a filter-grade biochar. Third-party results have shown 99.7% removal of metals over a year’s service.