scumboard

\\ˈ ̷ ̷ˌ ̷ ̷\ noun

: a device for the removal of scum in sewage-treatment plants

* * *

/skum"bawrd', -bohrd'/, n.

a board or strip of material partly immersed in flowing water to hold back scum.

[1895-1900; SCUM + BOARD]