EDITOR’S PICKS
Speaking for DuBois-Cooper, Jay Vermilye, commented: “Infrastructure Alternatives, Gosling Czubak and Lakeside Equipment all have a wealth of experience in this field. It was great working with them, and as a teamwe came up with a plan to modify the operation of the Plant that addressed the issues that Haring faced due to COVID”.
TomLarsen fromLakeside added: “Mixing is important in an oxidation ditch butmixing 100%of the time is not imperative. Sometimes, it ismore important to take advantage of denitrification and alkalinity recovery, especially when both nitrification and chemical addition for phosphorus removal creates lower alkalinity. In a lightly loaded system, you can even get conditions required for phosphorus released for luxury phosphorus uptake (the storage of phosphorus within the biomass in the form of polyphosphate), further reducing the amount of chemical required.”
Eventually settling on cycles of seven hours on/one hour off, IAI called in local engineers,WestMichigan Instrumentation Systems to adjust control settings and add a timer. The change provided enough denitrification to stabilize pH levels at around 7.1 to 7.3 for most of the year.
‘Good for the HaringTownship’
Nathan Filley continued: “Rusty Sietsema and his teamdid a very professional job.We work closely withmany skilled, specialist engineering companies inMichigan to help keep our treatment plants in top shape. We’re now also saving on some energy costs, which is good for the Haring Township, and we no longer have to add soda ash, so that savesmoney and time, too.
Nathan Filleymanually adjusts the rotor height
He added: “Although the fast-food outlets are required to use grease traps, a fair amount of fats, oils and greases (FOG) still comes into our flow of 75,000 gallons per day.We usually keep one rotor on 24/7 and bring in the second rotor as a lag when the DO gets to around 0.25mg/L below the setpoint – and shuts off at 0.25mg/L above the setpoint.
Lakeside’s E.A Aerotor Plant is constructed in a concentric, common wall design, with the outer loop utilizing the Closed Loop Reactor (CLR) process for extended aeration. Meanwhile, the inner area incorporates the proven Spiraflo Clarifier for final settling.
“I like to call it the‘Bullseye design’, continuedMark Hurley from Gosling Czubak. “It’s circular, with the ditches on the outside and the clarifiers in the centre. It’s a winner. The plant can be run in series, or with one ditch and both clarifiers, so the Lakeside set-up gives us lots of flexibility”.
Nathan Filley continued: “Ahead of what the Township hopes will see future investment in Haring, we have two reactors (each 220,000 gallons), with just one needed at themoment. Nobody could have really predicted the impact of the pandemic on our plant, so when the phosphorus rose to unprecedented levels, we tried turning the rotors down. I thought about how turning the rotors off at certain intervalsmight help the situation, so consulted leading wastewater equipmentmanufacturer representative, DuBois-Cooper in Plymouth,Michigan.
FOLLOW US
“Phosphorus levels remain themost challenging.When Gosling Czubak was designing the new plant, theMichigan Department of Environment, Great Lakes and Energy (EGLE) came out and set very stringent discharge levels to the ClamRiver. Overall, the change in the rotor timings has worked out better than any of us first thought.
“The Lakeside equipment is quality design; very robust. It is easy to operate,maintain and get parts for. The experts there, together with the back-up we get fromDuBois-Cooper and Gosling Czubak is always good to have when you’re in a pinch.
“I’mvery glad to see the return of that nice clean discharge water”.
Nathan Filley checks dissolved oxygen levels and trends for the oxidation ditch
June 2023 | 39
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