When staff at a small Michigan wastewater treatment plant began to tire of the labor-intensive process of unclogging its sludge pumps, as well as clearing the “jail bars” that were inefficiently filtering inorganic objects from the inflow, Tsurumi Pump provided an extremely effective and economical solution — automatic bar screens.

Enjoying a scenic location at the tip of the Thumb of Michigan on the shores of Lake Huron, the village of Port Austin has a population of less than 1,000 people. While the town was previously reliant on a gravity-fed lagoon treatment system, it later switched to the use of an aeration tank to handle the 85,000 – 200,00 gpd waste from its 338 households and dozens of businesses. The waste had to be initially piped to some 40 lift stations before being pumped to the headworks.

This is where things regularly went wrong, according to Port Austin wastewater plant supervisor Dale Jimpkoski.

“The manual bar screen would catch stuff like shoes, bags and plastic bottles, and we would have to use a garden rake to clear it about three times a day. The pumps were constantly clogging up because of sanitary wipes and other hygiene products, slipping through the ½ inch – ¾ inch gaps in the screen.”

Solid waste is now automatically retrieved, without risk of disintegrating into the sewage.

Management began to explore other solutions. One of Tsurumi’s competitors was initially approached, but its estimate of $95,000 to design and install a new bar screen system was quickly rejected by the village’s board.

Detroit Pump, a Tsurumi distributor in Michigan, suggested the front screen-type Tsurumi KW-6049 automatic bar screen as a solution to the plant’s problem. The board quickly agreed. The following month, the screen was installed at the headworks with the requisite controls and float system, for a total cost of around just $10,000.

“They asked us for a 2 mm bar spacing, which is very common for wastewater plants,” said Tony Misiak, process equipment sales manager at Tsurumi. “The flow now comes from town and activates the screen, which automatically rakes out the solid contents. Disposable wipes will clog up pumps and automated valves, causing downtime and other issues — because they don’t disintegrate in water, it’s important they don’t get ground up, which creates a higher burden on the water system.

The Tsurumi bar screen with in-line revolving rakes now quickly removes any solid matter lodged between or behind bars. It’s then transferred into a residue-collecting basket and then sent to a dumpster each month, saving the village labor costs.

A removable shanty protects the bar screen during snowy winter months

Sized for smaller wastewater plants

Designed for eliminating solids in the aeration and clarification tanks of small wastewater plants, and suitable for use where there are fluctuating water levels, Tsurumi’s KW mechanically cleaned front bar screens are designed for waterways up to 600 mm wide. They are constructed entirely from 304 stainless steel for high durability and corrosion resistance. Running costs are extremely low, with all KW models powered by a three-phase totally enclosed 0.09 kW electric motor. The KW-6049 — the highest-capacity model — can handle a throughput ranging from 357 gpm (at 1 mm bar spacings) to 982 gpm (at 5 mm bar spacings). In the event of atypical operation, a safety device will stop the motor immediately.

“As a small community, Port Austin is a perfect fit for Tsurumi bar screens,” Misiak concluded. “The wastewater plant staff are extremely happy with how it’s performing — not least because its automated screening has enabled them to move past manual cleaning!”

For Jimpkoski, another welcome bonus of the Tsurumi system was the surplus of cash left in his budget that was used to build a portable shanty structure that protects the bar screen from the notoriously harsh Great Lakes winters. Built on a 4 ft-square platform, it provides easy access for inspection purposes, as well as room for a space heater to prevent the formation of icicles and ensure the screen performs optimally in freezing temperatures.

“Unfortunately, we were hit by a tornado this June that blew the shanty away,” Jimpkoski said. “But thanks to the savings enabled by the Tsurumi installation, replacing it won’t be the financial burden it might otherwise have been. We would definitely recommend this bar screen to other municipalities of a similar size — it’s doing a great job!”

For more information on Tsurumi’s KE/KS KW/KM Series bar screens, click here.