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Using Septic Media Filters as Components of Alternative Septic Systems for Difficult Sites InspectAPedia®  -     Septic media filters Single pass, recirculating, sand, peat, textile, foam cube, other septic media filter types Septic filter capacity, maintenance, dosing control Septic filter product sources

This document discusses the design and use of various types of septic media filter systems. Media filter septic systems use a conventional septic tank followed by any of several methods to further filter and treat septic effluent before it is discharged to the soil, soil surface, or waterway. Also see SEPTIC & GREYWATER FILTERS for an explanation of septic filter devices for tanks and drywells, and see septic filter products listed at Septic Filter / Graywater Filter Sources.

When using a septic media filter system, effluent treatment is by both actual filtration and ultimately by a biochemical process as the filter "matures" and includes its own biomass. Both natural media filter septic systems (such as sand, gravel, or peat) and synthetic media filter septic systems (foam cubes, glass, slag) are used, and both single-pass and effluent recycling systems may be employed.

These different septic media filter types are explained here. We include a list of product sources for various types of septic filters.

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SEPTIC MEDIA FILTERS
  How Septic Media Filters Work
  Single Pass vs. Recirculating Filters
  Dosing Control for Septic Media Systems
  Types of Media Filter Material
  Sand Septic Filters
  Peat Septic Filters
  Textile Septic Media Filters
  Foam Cube Septic Media Filters
  Septic Filter Capacity & Maintenance
  Septic Media Filter Source List
SEPTIC & GREYWATER FILTERS

Septic media filters using textiles

Geotextiles are often used in septic effluent media filter systems; they can provide a large surface area and high water volume retention.

Fabric media is cut into squares and placed into a container, or hung in curtains in a container. Textile filters operate in a recirculating mode similar to that discussed above, but offer this advantage over sand and peat media: the larger effective surface area of the synthetic textile permits a much higher loading rate in gallons per square (or cubic) foot, thus permitting the media system to be designed into a physically smaller package.

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Septic media filters using open celled foam cubes

Two-inch open-celled polyurethane cubes are placed into a container to form a packaged or "pre-fab" septic media filter system which is used in either single pass or recirculating effluent mode.

Packaged foam cube septic effluent (wastewater) treatment systems may be placed entirely above ground (but of course will not work in an area of hard freezing climate).

Septic effluent is passed into the foam filter in small doses (1/10 gallon to 1 gallon per cubic foot per dose) using spray nozzles which dose the system from its top. An advantage of this system is its easy maintenance as the (clog prone) top few inches of foam cubes are easily removed and replaced.

Septic Media Filter System Capacity

A typical media filter system is designed using a flow of 50 to 65 gallons per day per occupant of the building served by the system. This number, cited by several authors including Jantrania, Minnis, and Kahn, Allen, and Jones, is less than other total wastewater load estimates but is considered by these authors to be realistic and is consistent with a number of studies performed on typical wastewater flow rates and quantities.

Septic Media Filter Maintenance

The system design maintenance required of the media filter system as well as its operating characteristics vary considerably depending on the media selected, with open cell foam and textiles providing higher gallons per day loading ability than peat and other media.

"Maintenance" in this case will refer to inspection of the media bed to determine when the media needs to be cleaned or replaced. Some systems, such as sand filter beds, are raked or agitated rather than replaced, but ultimately all filter systems will become clogged and face media replacement.

Septic filter media maintenance and replacement cost should be factored into estimates of alternative septic system costs when comparing alternative septic system designs.

Product Source List for Filters, Septic Filters & Wastewater Treatment Systems Using Filtration Methods

• Amphidrome from F.R. Mahoney, Associates, is a "sequencing batch reactor" or effluent recycling system (approved in MA) cycling effluent between the septic tank and a reactor vessel.
• AdvanTex- Onsite Wastewater Treatment Systems from Orenco uses a textile filter in a fiberglass basin.
• Biomicrobics wastewater treatment include BioSTEP, a screened pumping system, BioBarrier membrane bioreactor (MBR) which produces ultra-clean effluent Lixor, their submerged aeration system, SaniTEE wastewater screens and other wastewater treatment systems and products.
• Biocycle Wastewater Treatment a BioCycle Unit, Tertiary Polishing Filter and Monitoring System.- Ireland
• Bioren & Living Filter alternative wastewater treatment systems - Mass. USA
• Bioclere from AquaPoint (MA) is a trickle-filter effluent treatment system
• Peat Filters for septic effluent treatment, University of Minnesota Information Article on Peat Systems
• Ruck systems (in MA) "Traditional RUCK- [Residential Septic] Systems are passive innovative septic systems that are designed to remove nitrogen and provide excellent treatment for an on site septic system." Commercial products are also available. This is an in-ground filter system installed between the septic tank and the absorption field.
• SeptiTech Residential and Commercial Wastewater Pretreatment Systems include a fixed film effluent trickling filter and a patented effluent treatment media.
• Waterloo biofilter trickle type wastewater filter and systems using aeration combined with foam filter media; effluent is sprayed over foam.
• Product listing submissions are welcome; there is no listing fee.

References for this Septic Media Filters Discussion

My text draws heavily on Dr. Jantrania &Gross's work and on New York State Water Treatment Standards.

New York State Wastewater Treatment Standards - Individual Household Systems, Appendix 75-A (1990), Public Health Law 201(1)(1).

New York State Alternative Septic System Design Regulations, Wastewater Treatment Standards - Individual Household Systems, Appendix 75-A, of Public Health Law 201(1)(1) 1990.

Anish Jantrania, Ph.D., P.E., M.B.A., Consulting Engineer, Mechanicsville VA, 804-550-0389
NOTE: be sure to examine Dr. Jantrania's new (2006) book,
Advanced Onsite Wastewater Systems Technologies which can be
ordered from his publisher.

The Septic System Owners's Manual, Lloyd Kahn, Blair Allen, Julie Jones, Shelter Publications, 2000. IS N 0-936070-20-X

Onsite wastewater treatment systems, Bennette D. Burks & Mary Margaret Minnis. Textbook and reference manual on all aspects of onsite treatment. This is one of the best books we've reviewed on the subject, with an excellent balance of clear simple explanation and solid engineering. Topics: Soil & Site Selection, Hydraulics, System Selection & Design, Wastewater Biology, History & Mythology of Onsite Wastewater Treatment. $49.95, Hogarth House, Ltd, 800-993-2665 x327 to order *800 -993-2665 x327 (Univ. Wisc. Bookstore)

Boxerwood Gardens is an arboretum and nature center in Lexington VA, and the generous contributor of the illustration of a gravel-bed natural septic media filter system discussed above.

More Information on Building Diagnostic Inspections and Repairs

• Septic Filters & Graywater Filters in-tank septic filters or graywater filters to keep solids out of the absorption system


• The Septic System Information Website home page for this topic
• Septic Systems Inspection, Testing, & Maintenance- online textbook. Detailed how to inspect, maintain, repair information
• The Home Buyer's Guide to Septic Systems
• Septic Tank Pumping Guide: When, Why, How to pump the septic tank
• Home & Outdoor Living Water Requirements
• Septic Tank Capacity vs Usage in Daily Gallons of Wastewater Flow, calculating required septic tank size, calculating septic tank volume from size measurements
• How Big Should the Leach Field Be? - table of soil percolation rate vs. field size
• Septic System Drainfield Absorption System Biomat Formation - what leads to drain field clogging and expensive drainfield repairs
• Table of Required Septic & Well Clearances: Distances Between Septic System & Wells, Streams, Trees, etc.

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