One Unit Provides Many Innovations

Simple innovation eliminates the need for costly building alterations at the Monroe Metropolitan Wastewater Plant.

The Monroe Metropolitan Wastewater Treatment Plant, Monroe, Michigan, had just two doors for delivery of its new bar screens, which were to span three floors. One door was a standard building entrance, and the other was a dock door no larger than what you would find on a residential garage. However, building modifications were cost-prohibitive.

Duperon Corporation looked at the problem differently: The building wasn’t too small, but the equipment was too large. The solution? Each of the three FlexRake® units provided to the plant was designed in three separate pieces, eliminating the need for costly building alterations.

Simple Installation

Randy Sommers, maintenance supervisor for Monroe, was able to complete onsite installation with his own crew. He summarizes the simple installation by saying: “Duperon made it easy for us to do it. By not having any fixed mounts, we were able to weld at each floor location. It went extremely well. We had one unit up in eight hours. We took the units off the truck in one piece and disassembled them into three pieces. Then we took the pieces into the room where they were going to be assembled.”

This simple, effective installation process set a standard for the Duperon® FlexRake® that would be met and surpassed in the city’s time with the equipment.

“I think it’s very ingenious. All my problems were eliminated with the Duperon equipment,” Sommers said. “We have two Duperon® units now, and we need only one. One Duperon® unit can handle what the three old units were handling.”

Sommers said that another benefit of the Duperon units was that the screenings turned out to be 50% drier than before. He said when they used to take the hoppers and dump them, the hoppers were half-full of water but that now, there’s very little water and less odor.

“The screenings were saturated before, and now they are dry, with no water splashing out into the yard as they truck it to the dump pad on the other side of the plant,” Sommers said.

Fighting Grease

Duperon has continued to provide simple solutions. In 2002, the city of Monroe conducted a “cleaning project” initiated for the purpose of raising awareness of the grease problem within local businesses like car washes (for wax) and restaurants (for grease).

Sommers chemically treated the influent sewer lines to break down the accumulation of wax, grease, and similar solids in successive stages. He and his crew left for the evening with one Duperon® FlexRake® in operation.

When they returned the following morning, Sommers discovered that the grease, wax and other solids had hit the plant nearly at once, creating a “grease attack” at the plant’s headworks. In fact, the plant had been hit so hard that each FlexRake® scraper was removing several inches of debris buildup with each pass at the screen. This aggressive removal resulted in the overflow of the site’s dumpster and an overload of the belt conveyor.

“The grease attack knocked the conveyor out and completely covered it in grease – but the Duperon® FlexRake® was still operating and discharging the grease when we came in the following morning,” Sommers said.

By the time Sommers had emptied the first dumpster and restarted the conveyor, the second dumpster was already full. Although it was a mess for Randy and his crew to clean, one Duperon® FlexRake® completely handled this grease attack, preventing damage to the downstream processes.

The Innovations Continue

The diligence of the Duperon® FlexRake® in this situation is just one example of the equipment’s ability to save time and money. In 2003, a cost-of-ownership study was performed to compare equipment expenses at the plant. The study compared the years 2002 – the last year that the previous bar screen equipment was in place at the city of Monroe – and 2003, the first year of operation using the Duperon® FlexRake®.

In 2002, the city of Monroe spent $11,773.50 on operation and maintenance, including rental costs for necessary equipment, manpower, and materials. In 2003, the city of Monroe spent $0. The biggest benefit was the elimination of 15 confined space entries per year.

Duperon’s innovations have continued in the city of Monroe. In 2007, the city installed another FlexRake® for use in the plant’s UV operation. The unit was positioned behind the plant’s clarifiers, which are all open to sunlight. The abundance of sunlight promotes algae growth, which became an issue as it flourished, tangling on the UV tubes. In some cases, the growth was so aggressive that it would snap the tubes. Eventually UV modules were pulled twice a week for cleaning and damage control.

While awaiting funding, the city of Monroe installed a manual barscreen. This screen added to the plant’s maintenance schedule, and when an automated solution was deemed necessary, the FlexRake® was a natural choice. “It’s really done the trick,” Sommers said.