1. Take out the hoses for air supply from the nozzles of raw water air-lift pump and of the air-lift pump for coarse filter aeration carefully. Remove the hoses in a parallel way with the axis of the nozzle – do not move with it side to side!

2. Unfix the hose for raw water pumping from the hanger on the WWTP wall.

3. Take out the raw water air-lift pump from the filter of coarse impurities.

4. Remove the filter of coarse impurities from the hanger and take it out of the WWTP.

5. Clean the filter from settled impurities.

6. In the end, rinse the pipe with a stream of pure water.