Recirculating Sand Filter Treatment Systems
Illustration courtesy of Orenco SystemsŪ
Photo courtesy of Orenco SystemsŪ
|
|
Recirculating sand filters (RSFs) are an excellent method for bringing wastewater to advanced levels of treatment. Even with variations in volume and strength of incoming wastewater, effluent from an RSF consistently has BOD and TSS levels less than 10 mg/L and total nitrogen reductions of 40% to 50%. The treated effluent can be distributed subsurface in a shallow drainfield for polishing and disposal or, where allowed, disinfected for reuse or surface discharge.
Sand filter technology has been around for over 100 years! Orenco Systems is the world leader in alternative wastewater treatment systems. RSFs are simple to construct allowing local contractors to build them using locally available materials and Orenco's pre-engineered equipment package. Modern designes let you add modules when demand justifies expansion, so capitol costs are deferred. Pre-engineered packages range from 400 gallons per day to over 50,000 gallons per day. RSFs have been installed all around the northeast and throughout the world. With low power cost and no need for full-time, highly skilled operators, an Orenco RSF can be depended on for treating wastewater more efficiently than other more complex and costly technologies.
How does a RSF work?
Primary treated wastewater from the septic tank(s) flows first to the recirculation tank where mixing and natural biochemical treatment take place. Pumps in the recirculating tank deliver the wastewater to the sand filter bed in frequent, timer-controlled doses. With each dose, the wastewater percolates through the coarse sand and its contaminants are removed and broken down by naturally-occuring microorganisms living on the sand particles. The highly aerobic flow from the sand filter bed then drains back to the recirculation tank for mixing with incoming wastewater. After a few more passes through the sand filter bed and recirculation tank, the treated wastewater is ready for discharge. The liquid level in the recirculation tank determines whether the returning treated effluent returns to the recirculation tank or passes on to final discharge system, however at least 80% will return to the tank.
The revolutionary Biotube® Pump Vault protects downstream components and the sand filter bed. Orenco's lightweight, stainless steel pumps are designed for high cycle life to provide the numerous small doses (microdosing) that make the sand filter perform at its best.
The control panel has a programmable timer to control the dosing, meters to track the flow, and a current sensor to actively monitor pump operation. System status can be monitored on site or remotely with optional telemetry. Panels can be built to Orenco's suggested specifications or customized for special needs.
In larger systems, distributing valves automatically direct flow for sequential dosing of small zones in the sand filter. The valve requires no electricity and the assembly is configured to make its maintenance and monitoring simple.
The sand filter manifold* is designed and custom built to achieve maximum scouring velocity and to spread the flow evenly over the filter bed. Sturdy, pre-slotted underdrain pipe collects the filtered effluent for conveyance to the recirculating splitter valve at the recirculation tank.
The recirculation splittler valve* works in conjunction with timer controls to maintain a constant recirculation rate, regardless of the rate of incoming flow. Patened design with only one moving part provides the most cost-effective and efficient flow splitting device.
Applications
- RV and mobile home parks
- Private residential developments
- Small communities
- Campgrounds
- Highway rest areas
- Schools
- Single family homes
Advantages
- Clear, odorless effluent
- Simple design and construction, low up-front costs
- Simple maintenance -no full time operator, low O&M costs
- More consistent effluent quality than other treatment systems
- Complete pre-assembled equipment oackages for any size job
- Approved in most states for general use often with a reduction in final disposal system size
- Long track record documented nationwide
The following chart gives performance expectations for effluent discharged directly from the recirculating sand filter:
| Treatment System |
BOD5 mg/L |
TSS mg/L |
TN mg/L |
| Orenco RSF |
< 10 |
< 10 |
40-50% Reduction |
Considering a recirculating sand filter yet have more questions? Give us a call, toll free (877) 212-3219.
To learn more about Orenco's Recirculating Sand Filter Systems, visit Orenco Systems' RSF website.
* Covered by one or more of the following patents: 5,360,556; 5,492,635;5,480,561; and 4,439,323.
|
