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