After five years in operation, an old automated filter screen at the Oconto Wastewater Treatment Plant was wearing out. Several of its lifting teeth had broken off, and worse, it was letting rags pass, leading to problems downstream.

Managers at the Wisconsin facility faced another problem too: foul odors. The heaping piles of fecal matter, rags and sticks the screen pulled from the channel were creating an unhealthy and obnoxious odor in the headworks building — the same place where operators had their office.

With his bar/filter screen becoming toothless and useless, plant operator Steve Woodworth took action and started designing a new headworks system for the 3.2 mgd facility, with plans for better screenings performance and, for his own sake, better odor control. After a rigorous analysis of screens, Steve selected the Monster Separation System from JWC Environmental.

“We wanted to eliminate the mess of the old bar screen,” Woodworth says. “It was really bad — piles of fecal material, rags and sticks all sitting in the discharge trough, really gross. The compactor would get so overwhelmed at times, it wasn’t dewatering; it was just pushing stuff along.” The unique Monster Separation System combines a high-flow fine screen, in this case a Bandscreen Monster, and a heavy-duty washer-compactor called Screenings Washer Monster.

Together, the system captures and cleans unwanted wastewater solids, producing a dry, compact cake with no visible fecal matter; moreover, the reduction in odor was tremendous and a great relief for Woodworth and his crew.

“We were introduced to the Screenings Washer Monster at a trade show, and we saw the cleanliness of the system. We had a two-week on-site demonstration and, after I brought the commissioners out to take a look, we were approved to purchase one.”

Prior to installing the SWM, the Oconto operators were removing a 50-gallon drum of screenings twice a day, but now empty the drum about once a month, according to Woodworth. The key to reducing the discharge by more than 90% is the SWM’s process: wash, grind, wash, compact and dewater.

The integrated Macho Monster 40000 grinder helps break up clumps for more effective washing and homogenizes the material so it is easier to dewater and compact. Nearly all of the fecal matter is liquefied and goes back into the plant flow where it belongs. Oconto’s new Bandscreen Monster is an innovative traveling fine screen with a unique inside-out flow pattern. Wastewater enters the screen and then flows through the left or right sides of the screen through the moving panels. The panels, with 1/4-inch perforated openings, lift solids and unwanted material out of the flow and to deck level where a series of deluge spray nozzles flush the material into the Screenings Washer Monster. Since solids only touch the inside of the screenings band there is no chance of carryover or bypass.

“This is definitely an improvement and a really great system; we don’t see that mess anymore,” Woodworth says. “Before, we had to watch the bar screen and compactor constantly, now we don’t need to worry about it daily. I’d almost say we can forget about it.”

Another benefit for the Oconto plant operators is an improvement in downstream processes, since the Bandscreen Monster removes many of the troublesome solids at the headworks. The flow sampler would frequently clog with rags prior to the installation of JWC’s fine screen, but now the plugging problem has disappeared. Oconto’s wastewater treatment staff helps keep the local environmental clean and healthy, while the JWC Monster Separation System helps keep the facility’s treatment process safe and trouble-free.