Sludge level and quality measurement

The sludge accumulated at the bottom of wastewater treatment ponds reduces the useful volume and therefore the retention time available to the treatment of the wastewater. The measurement of the level of sludge accumulated in the ponds must be carried out at least every three years or every year when the proportion of sludge reaches 10% of the total theoretical volume of a pond, or when the veil of sludge is less than one meter from the pond outlet pipe.

Measuring the sludge level ensures that the accumulation of sludge does not have the effect of reducing the retention time of wastewater in the ponds, which can cause:

• The passage of sludge to the effluent and the subsequent risks of contamination of the receiving watercourse (e.g. proliferation of blue-green algae)
• Poor purification performance of the station (non-compliance with discharge standards)

Equipment breakage or reduced performance of the aeration system used in ponds.