The primary purpose of a Pretreatment System, simplistically stated, is to reduce the high levels of organic matter contained in wastewater. Private Onsite Wastewater Treatment Systems (POWTS) having a pretreatment unit are those POWTS that will have some type of pretreatment unit added to the standard POWTS components. For example, a standard mound POWTS will always consist of the following components: a septic tank, a dose tank (pump chamber) and the mound (absorption cell). A pretreatment unit may be added down stream of the septic tank thus improving the quality of the wastewater and allowing reduction in system sizing or overcoming poor soil conditions.
Pretreatment Service Frequency
There are different types of products on the market that can perform this function. Some will require a service provider to come to the property being served by the pretreatment device to do regular service maintenance on the device. The type of device installed will determine the service frequency required. Some devices will require maintenance every 6 months and some once a year. A service contract is required between the licensed service provider and the owner of the pretreatment unit. Included in that contract will be the cost of the service provided, service frequency of the unit, duration of contract period and any other additional services provided.
Reasons for Pretreatment
There are several reasons that a pretreatment unit is used. They would include, small lot size, reduction of absorption cell size, i.e. length, width and possibly height, impedance of clogging mat formation, restoration of a failing POWTS and high strength waste level reductions. If you have a failing POWTS and you want to try to restore it by adding a pretreatment device to your existing POWTS it may be possible.
POWTS Restoration & Replacement
However, the restoration by the aerobic unit will be a slow process and may require some reduction of wastewater generation by the homeowner and intensive monitoring by the POWTS maintainer. Installing a pretreatment unit with your POWTS will extend the normal life of your POWTS. Maintenance of your system is the key to system longevity.
Another reason a pretreatment device would be installed is when an existing residence being served by a POWTS that is failing and a replacement POWTS is being sought. Due to lot size limitation a pretreatment device could be used to reduce the overall size of the POWTS cell area and forego the installation of a holding tank as the replacement POWTS. A pretreatment device can also reduce the separation distance needed from the soil surface to a limitation such as bedrock or groundwater. In some applications this can result in being able to install a different system type.
Commercial operations such as restaurants, taverns, banquet halls and other facilities that generate high strength wastewater are required to utilize pretreatment units in order to improve the quality of the wastewater before final disposal to the soil.