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SOLIDS PROCESSING BREAKING FREE FROM DEBRIS AND RAGS
Drum screens from Lakeside are dealing with debris at the City of Clyde’s wastewater treatment plant
T
he Wastewater Treatment Plant at the City of Clyde (Ohio) went online in 1986; and since then has taken a proactive approach to its sanitary/storm separation process. “Everything here looks brand new. It’s a real pleasure to visit,” said Paul Matrka from leading equipment provider, Smith Environmental.
Behind the scenes, in an arduous week- long operation, the treatment plant team recently removed 37 tons of debris from just one oxidation ditch. Hardly the most pleasant of tasks, which despite a vac truck, involved a huge amount of manual labour. The same clean-out job is due to take place soon for Clyde’s second oxidation ditch. The legacy of all that debris is an accumulation over almost 40 years, but as Treatment Plant Superintendent, John Biggs explained, the investment in new screens has completely transformed the whole intake process and made life considerably easier for the plant’s equipment further down the line.
“Our new screens (made by Lakeside) have made a world of difference,” he said. “We are very pleased to be rag-free.”
Ninety per cent of the time at Clyde, just one of the two new screens is in operation, but for storm events, which can suddenly send flows shooting up from 1.6MGD to 6MGD in a short space of time, that second screen is essential. Those barraging storms, coupled with snow-melt in the spring and mountains of leaves in the autumn were a severe test for this treatment plant (situated roughly halfway between Toledo and Cleveland in the US), but now, on a day-to-day basis and in storm events, the screens hold firm. “Apart from large objects such as rocks and bricks, our old bar-rake screens didn’t capture that much,” added Biggs. “The rags would just work their way through to the oxidation ditches, creating problems all through the process, especially with pumps getting plugged. Dealing with the initial storm surge that picked up all the accumulated material used to be a real challenge, but now, despite several storm events, we’ve not had an issue at all. The screens handle it. Right down to pieces of debris the size of a cigarette butt, the Lakeside screens remove it; even some of the grit that attaches itself to rags is not a problem. We’re removing 1-2 cubic yards of
16 FEBRUARY 2023 | PROCESS & CONTROL
debris per week. It’s fantastic.”
The all-stainless-steel constructed Lakeside Raptor Rotating Drum Screens remove plastics and other floatable material that, as Biggs stated, can have a very detrimental effect on various areas of the treatment process. Captured screenings are compacted, dewatered and washed free of most organics to approximately 40 per cent solids. Volume is reduced by 50 per cent and weight by 67 per cent, thereby reducing disposal cost. Flow is directed into the screenings basket where fine solids are captured by a ¼-inch diameter perforated plate screenings basket. When the upstream water level rises to a high-level set point, the screenings basket begins to rotate for removal of the captured material. With the aid of the lower spray wash system, the debris is then removed from the rotating basket and falls into a collection trough. The debris is then removed from the trough by a central screw conveyor. The conveyed material travels up the inclined transport tube where the material is washed, compacted, and dewatered prior to being discharged into a debris container. “There are always a few things to fine-tune when introducing new equipment,” said Biggs. “With the screens, when running at the same time, which isn’t very often, there wasn’t quite enough pressure at first, but Lakeside was on the case immediately.” Matrka confirmed: “That’s one of the great facts with Lakeside Equipment Corporation; they really care about the installation. They have a wealth of design and engineering experience, so they stepped up straight away
to make everything right with a booster pump.” With each Lakeside screen having a capacity of 5MGD, peace of mind now prevails at Clyde, although Biggs and his team do of course keep a watchful eye on the plant’s SCADA system during storm events. With just one screen required ninety per cent of the time, there is also the benefit of rotating them once per month, with pressure-washing once per week as a preventative maintenance measure. “Overall, the Lakeside screens are user- friendly and very maintenance-friendly,” concluded Biggs. “We did plenty of homework, speaking to several operators in the state before making our investment. We firmly believed that Lakeside was the best equipment for the best price; and our decision has proved a very wise one for the plant and for the City of Clyde. They are the best thing we’ve done here.”
Lakeside Equipment
www.lakeside-equipment.com
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