What is Secondary Treatment?
Secondary treatment (in the on-site septic industry) refers to a device that cleans your wastewater before it goes to your absorption field. Usually, this treatment device is installed downstream of your septic tank (prior to your septic absorption field or dosing tank) and treats the liquid effluent.
Secondary treatment benefits…
All septic absorption fields will fail over time. How long your system lasts is a function of the amount and strength of the wastewater you are putting into your system. It is generally understood how lots of water can stress your absorption system but the concept of waste strength is often under appreciated or not understood.
Over time, the soil surface at the bottom of your absorption field will develop a bio-mat (a layer of anaerobic bacteria) that grows into a mat that seals off the soil interface, continues to slow the rate of absorption and eventually makes the system fail (i.e. back up into your newly remodeled bathroom).
Secondary treatment cleans the wastewater and removes most of the nutrients needed by these evil-doer bio-mat bacteria. As part of the cleaning process, they also induce oxygen into the wastewater that promotes good aerobic bacteria instead of the bad.
There are many brands and types of secondary treatment systems that utilized different methods to clean your waste water. There are Aerobic treatment units, recirculating media and sand filters, and algae and plant based systems just to name a few. Here are some examples of these systems.
Oldcastle Precast – Hartford Concrete Algaewheel Technology
Secondary Treatment Costs…
These treatment units typically cost between $3,000 and $12,000 for a single family residence. These systems are expensive because they are active systems that utilize pumps, electronic controllers and often telemetry systems for monitoring the devices remotely.
All of these systems require regular maintenance (some more than others).
The bottom line…
Secondary treatment devices can keep your new absorption field working a long, long time. I have personally seen these units even “repair” failed system by breaking up the existing bio-mat in the absorption field allowing the field system to work again.