WWTP Trickling Filter Towers Improvements

Monett faced aeration issues, hampering its capacity and compliance with permit limits. Biological treatment primarily relied on trickling filter towers, which led to snail issues. Repairing the snail removal equipment was imperative. One tower experienced media failure, necessitating a complete replacement. This left the plant with a 70% loss in treatment capacity. However, the towers couldn’t function without a working snail removal system. Ten brush rotors are crucial for aeration in the activated sludge basins. They had severe mechanical problems. This reduced their air output and hurt the entire process. To stay compliant, six old brush rotors were retrofitted. This let them do partial treatment during further upgrades. The reaining four rotors would be replaced with a diffused air system later.

The City retained Allgeier Martin (AMA) to assess the plant and propose solutions. After evaluation, the recommended plan included:

• Finalize repairs on 6 of the 10 brush rotors.
• Abandon trickling filter towers and snail removal gear. Use a cheaper option.
• Replace the remaining brush rotors with diffused air and blowers. Add air to existing oxidation ditches. This compensates for lost capacity from abandoning the trickling filter towers.
• Reinstate primary clarifiers to remove some of the load from the activated sludge process.
• Reactivate the sludge thickener and old anerobic digesters with a new diffused air system.
• This approach reduces the load on the activated sludge process. It also increases aeration capacity. This allows the plant to operate without replacing the trickling filter tower media or upgrading the snail removal equipment.
• The City sought ARPA grant funds from DNR for the proposed improvements.
• AMA helped the City get bids from General Contractors. They also provided construction engineering services until the project was complete.