Secondary Clarifier: Mixed containment of excess biomass

Challenge:
Due to changed influent characteristics, within a short time frame an extensive growth of biomass had taken place in a WWTP. Although the secondary clarifier could handle the raised biomass concentration, the sludge dewatering couldn't cope with the additional excess sludge. An emergency solution was required to keep the biomass concentration at acceptable levels.

Solution:
United Rentals engineered an emergency solution based on the following principles:

• A tie-in & related hoses and manifolds to transfer the Return Activated Sludge into multiple containment units.
• A series of Mix Tanks, installed in parallel, to hold the biomass in suspension until an additional sludge dewatering solution could be arranged.

Benefits:
With the United Rentals solution in place, the biomass concentration was kept at the correct level and the clarifier could continue to operate under normal conditions. Our customer gained time to identify the most affordable long-term solution to dewater the excess sludge. Due to the installation of the Mix Tanks, potential clogging during the transfer of the biomass towards the additional sludge dewatering capacity was prevented.