Layered media backwash with internal drainage tube

A wastewater filter includes a container having a bottom and a side wall that cooperate to define a filtration space. A first filter media is positioned within the filter space to define a first media layer, and a second filter media different from the first filter media is positioned within the filter space above the first media layer to define a second media layer, the first media layer and the second media layer cooperating to define an interface plane. A drainage tube is positioned within the second dielectric layer and has a first end positioned at a first non-zero distance above the interface plane and a second end disposed at a second non-zero distance from a top surface of the second dielectric layer. A backwash fluid line is positioned to inject a backwash fluid into the first filter media, and a backwash gas line is positioned to inject a backwash gas into the drainage tube. 一种废水过滤器，包括具有底部和侧壁的容器，底部和侧壁配合以限定过滤空间。第一过滤介质定位在过滤空间内以限定第一介质层，并且与第一过滤介质不同的第二过滤介质定位在过滤空间内第一介质层上方以限定第二介质层，第一介质层和第二介质层配合以限定界面平面。引流管定