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| Recirculating Sand Filter Packages |
Recirculating sand filters (RSFs) are similar to ISFs except that a portion of the treated effluent is returned to a recirculation tank. There it is used to dilute the effluent from the septic tank before it is applied to the filter. Recirculation, in combination with properly selected media, allows higher application rates — as high as 5 gpd/sq.ft. for RSFs vs. 1.25 gpd/sq.ft. for ISFs — and stronger organic loadings. Consequently, RSFs can provide good wastewater treatment for small commercial and multi-family applications, such as subdivisions, campgrounds, rest areas, resorts, and schools.
RSFs consistently produce effluent that has BOD and TSS levels under 10 mg/L and total nitrogen reductions of 40-50%, even with variations in volume and strength of incoming wastewater. Like Commercial AdvanTex Treatment Systems, RSFs are modular and can therefore accommodate large design flows. However, because sand does not have the high surface area, void space, and holding capacity of textile, RSFs require much more land space. (For example, a 5,000-gpd RSF system treating residential waste requires 1,000 sq.ft. of treatment area, whereas a 5,000-gpd AX100 system requires only about 250 sq.ft. of treatment area, reducing the footprint of the system by three-quarters.)
Orenco’s engineers assist system designers with recommended media specifications, tank sizing criteria, application rates, dosing frequency, drainfield sizing, and maintenance requirements. Standard designs and packaged kits are available.
Orenco’s Recirculating Sand Filter packages include the following:
• Complete pumping system
• Distributing valve assembly and recirculating splitter valve
• Manifold and underdrain
• Remote telemetry control panel
• Liners
• Access risers and lids |
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