Symptoms

• Presence of oils and greases in the clarifier effluent

Main causes

• Incorrect skimmer operation

Investigations and analyses

• Check the state of the skimmer, and the correctness position

• Check the oil and grease content in the incoming wastewater and compare it with the design data

Remedial actions

• Install a screen in the clarifier: floating materials exceed the outlet weir, and therefore periodical screen cleaning operation are needed

• Install sprinkler in order to convey floating material to the extraction zone

• In case of wastewater containing high quantity of oil and grease evaluate the chance of installing a flotation unit upstream the clarifier