Recirculating Sand Filters - RSF (Subdivisions, Communities and Commercial)
RSF’s are a type of sand filter adapted for larger flow applications.. They are able to meet the 10/10 effluent quality standard at substantially lower cost than other systems. According to the Water Environment Federation:
"Sand filters are similar to other natural systems in that natural material and processes are used for wastewater treatment. They consist of medium to coarse sand over which settled wastewater is applied. Biological treatment of the wastewater occurs as the waste percolates through the sand bed.” “Effluents that exceed secondary treatment standards are achieved with little power consumption and operator attention. Sand filters have a long history of successful performance, but until recently they were a technology forgotten as they were abandoned for mechanical plants.”
“Hundreds of small communities and rural schools in the U.S. are now using the technology. Experience has shown them to be trouble-free, providing advanced treatment levels at reasonable construction and operation costs."
RSF’s are often used in combination with a STEP system to serve commercial and/or community collection and treatment needs, and the cost savings of such a marriage can be substantial. Onsite Systems and Eagle Engineering have designed or assisted other engineers in the design of numerous sand filters ranging in size from 3000 – 15,000 Igpd.