Absorbent peat media filters consist of a distribution system, peat media, and an underdrain system. Peat filters typically come in pre-fabricated modular units made of fiberglass or high-density polyethylene. Some filters are gravity-fed, using a tipping distribution-box mechanism. Others are pressure-dosed using either demand or time-dosing. Types of peat material are sphagnum peat (from North America) and coarse fibric peat (from Ireland).
Peat tends to settle, decompose, and/or deteriorate over time and may need to be replenished or replaced entirely at some point during use. Peat replacement frequency is dependent upon wastewater flow and characteristics, and the type of peat used. Typically, peat needs to be completely replaced after 4 to 12 years of use. Peat replacement frequency may also be dictated by state or local regulations.
Additional peat material may need to be added to the module yearly to ensure that distribution laterals remain covered; otherwise, odor problems may occur (especially during cold months of the year).
After effluent passes through a peat filter, it can be pressure-dosed or gravity-fed to the final treatment and dispersal component.
