drænbed
Drænbed is a term used in wastewater treatment to describe a constructed area designed to treat wastewater through natural processes. It typically consists of a lined pit filled with gravel or sand, into which wastewater is intermittently dosed. This allows the wastewater to percolate through the permeable medium, where it is treated by a combination of physical filtration and biological activity. Microorganisms that colonize the gravel and soil break down organic pollutants in the wastewater.
The design of a drænbed can vary depending on the specific application and the volume of wastewater