septage

Septage is the semi-liquid residue that accumulates in septic tanks. It is composed of solids, liquids, and scum that settle out of wastewater. Septage is primarily generated from household wastewater, including sewage from toilets, sinks, showers, and washing machines. When wastewater enters a septic tank, heavier solids sink to the bottom forming sludge, while lighter materials like grease and oils float to the top forming scum. The liquid in between is known as effluent.

The collection of septage is a crucial part of maintaining a functioning septic system. Over time, the sludge and scum layers thicken, reducing the tank's capacity and its ability to treat wastewater effectively. This can lead to system failures, such as backups and groundwater contamination. Therefore, septic tanks require periodic pumping by a professional to remove the accumulated septage. The frequency of pumping depends on factors like tank size, household occupancy, and water usage.

Once removed, septage must be treated and disposed of properly to prevent environmental and public health risks. Typical treatment methods include dewatering to remove excess liquid, followed by further processing like composting or anaerobic digestion. Disposal options can include application to agricultural land as fertilizer, landfilling, or discharge to a municipal wastewater treatment plant, depending on local regulations and the specific treatment the septage has undergone. Regulations regarding septage handling and disposal vary significantly by jurisdiction.