**5. Removal of sand and fine particles in wastewater**

In the last steps of the physical treatment of wastewater, it is necessary to provide a solution for the removal of very fine sand. One of the best solutions in these conditions is floating using equipment such as a classifier. Grit Classifier is placed in a simple but functional wastewater treatment equipment group that has different parts such as body, cochlear conveyor, and Electra Gearbox. Water enters the grit classifier body from the inlet valve. The cochlear conveyor flows the strip and creates centrifugal force. Fine particles and sand grains are separated from the water due to the creation of this force. They move to the device output and exit from it. Finally, wastewater without sand particles and similar items will be obtained.

**Figure 6.** *Sewage settling pond.*
