The wastewater passes through a screen to remove rags and large debris. The screening system washes and dewaters the debris before discharging it into a garbage can.
The screened wastewater then flows to an aerated grit chamber that facilitates the sedimentation of heavier inorganic materials, such as sand and grit, by reducing the velocity of the wastewater. The grit chamber is aerated to increase the dissolved oxygen content of the wastewater, which supports the aerobic biological process used later in the treatment system. The material collected at the bottom of the grit vessel is removed by an auger and mixed with biosolids generated during the treatment process.