The GDE/D model performs: screening, sand removal, fat and grease manual removing.
GDE o GDE/D could be supplied in 2 models:
Based on the chosen model, pre-treatment combined unit, you can get (it will be possible to get) a different type of screening.
The sewage goes through the screening section for the solid parts removal.
Then the sewage falls down a decantation tank where the particles go down. Here an extraction spiral removes them.