May 18, 2015

Surviving the Sludge

Coeur D’Alene, Idaho, facility uses grinder to process sludge after macerator explosion

The Coeur D’Alene, Idaho, wastewater treatment plant has been in operation since 1939, making it one of the earliest examples of a municipal secondary-level treatment facility in the world. Since then, the facility has been overhauled significantly to keep up with demand, area growth and innovations in wastewater treatment technology. Since 1982, the plant has undergone 11 major “phases” of construction, culminating with solids-handing and administration buildings. These projects added new anaerobic digesters, sludge gravity thickeners, belt filter presses for biosolids dewatering, plastic-media trickling filters with solids contact tanks, secondary clarifiers, a chlorine contact tank, de-chlorination with sulfur dioxide, a chemical systems center for phosphorus removal and foul-air treatment with compost-bed biofilters.

The treatment plant was having continual problems with two sludge macerators, in part because of their durability. During design, someone misread the maximum pressure rating as 150 psi—the macerators’ true maximum pressure rating is 30 psi. Eventually, one of the macerators exploded and flooded the underground pump area with sludge. The accident took about 12 hours to clean up. The crew pulled a Muffin Monster grinder from its backup stock, and it took care of the sludge immediately. The unit features a low-speed, high-torque design that keeps waste flowing freely, eliminating the danger of clearing pumps by hand. The cutters and spacers are constructed from heat-treated alloy steel, ensuring enhanced durability throughout the product’s lifetime. The Muffin Monster quickly adapts to existing pipeline or channel applications with little or no modification, and the compact design of the cutter and reducer allows the use of small, energy efficient motors—3 to 10 hp (2.2 to 7.5 kW).  

Impressed with the performance and quality of the Monster grinder, the treatment plant manager requested approval to purchase three additional 10K series Muffin Monsters. With the macerators, operators were performing maintenance every 120 hours (every five days); with the Muffin Monster, the team can perform a simple visual inspection every few weeks, and the plant has not had any issues with ragging or backups.

JWC Environmental


2850 S. Redhill Ave., Ste. 125

Santa Ana, CA 92705

United States

Phone: 949.833.3888

Fax: 949.833.8858

[email protected]