Symptoms

• High TSS content in the secondary clarifier effluent

Main causes

• Bad sludge settling characteristics

• High overflow rate

• Not properly functioning of the scraper

Investigations and analyses

• Measure the TSS content in the clarified effluent

• Measure the recycle and the waste sludge flow rate

• Check the installation correctness of the outflow weir, in particular the regularity along all the weirs

Remedial actions

• Enhance the weir layout and eventually place some screen wind

• Increase the sludge extraction and recycle flow rate