Complex organic media adsorption as a cost-effective stormwater treatment

Ecology Auto Parts, an industrial recycling company, launched a three-year lab and field investigation program to determine whether complex organic media can be used to attain compliance with μg/L (part per billion) stormwater discharge standards.In addition to meeting concentration standards for oil and grease, pH, conductivity, turbidity and metals, key items included meeting the company objectives of: low cost, using gravity flow systems, eliminating hazardous chemicals, and using facility staff.Following extensive research and bench scale tests, the company settled on complex organic media (agricultural products) to provide the contaminant removals needed.The theory was that oil and grease and particulate matter could be removed by media filtration, with the metals on interest adsorbed on the media itself.A two-day field testing program using four tons of organic media were used in an existing collection and treatment basin.Stormwater from the facility was collected in a sump and sprayed onto the surface of a 0.75 meter deep bed.The results showed significant reductions in all parameters: 96% (Al), 85% (Cu), 95% (Fe), 97% (Pb) and 91% (Zn).2015 results for additional installations indicate compliance with the new discharge standards.Oil and grease was non-detectable, suspended solids were reduced by 83%, hardness was reduced by 60% and turbidity by 75%.Conductivity was unchanged and pH was lowered by about one pH unit.Based on this field testing program, it is shown that complex organic media are the most cost-effective stormwater treatment methods for meeting industrial standards while meeting other cost-effective and low-hazard treatment goals.