Sewer systems aren't found everywhere they're needed, and natural conditions don't always lend themselves to traditional septic tank set-ups. Traditional systems don't adequately remove these compounds. Excessive nitrates and phosphorous are suspected health hazards and, when flushed into waterways by surface water run-off, cause extreme plant growth that can choke out native plants and aquatic life. Safferman's design attaches two additional tanks to the one normally used in an on-site system.
Wastewater flows by gravity and the effluent recirculates through the multiple passages.
Microbiology is used to convert nitrates into nitrogen gas, which is inert and can be safely vented into the environment. Filters used to absorb phosphorous will last about a year before they will need to be replaced. Used filters can be used as landscaping materials, Safferman said. The whole apparatus is buried, with nothing more than manhole covers showing above ground. He estimates a 20 to 40 percent increase in cost to a typical on-site aeration system for individual houses, trailer parks and small office buildings where sewers aren't available.