Symptoms
Rapid abrasion of moving mechanical equipment downstream the grit chamber
High inert content in the biological aeration tank
Quantity of collected grit smaller than normal conditions
Main causes
High velocity and / or too short hydraulic retention time
Investigations and analyses
Measure inorganic suspended solids inflowing and out flowing the grit chamber at different wastewater flow rates
Measure the velocity corresponding to the different wastewater flow rates;
Measure the air flow rate in case of aerated grit chamber
Remedial actions
In the rectangular horizontal-flow grit chamber, increase the frequency of grit removal in order to increase the available water section
Reduce the velocity of roll or agitation
Increase the number of the grit chamber
Reduce air flow rate in case of aerated grit chamber
Replace the pump
Modify the solids removal system upstream