Wastewater plant upgrades might be in Rantoul's future

Rantoul Press assistant editor

The village of Rantoul’s wastewater treatment plant is in need of some upgrades.

That was the consensus opinion of Randy Patchett and Curt Craigmile of Burns & McDonnell, an engineering firm based out of Downers Grove the village hired last summer to perform a feasibility study on phosphorus and nitrate removal for its wastewater treatment plant.

Potential upgrades could cost the village anywhere from $950,000 to $4.6 million to $10.9 million, depending on two nutrients options removals Burns & McDonnell recommended.

The reason for the study is the Illinois Environmental Protection Agency (IEPA) has placed limits on the nutrients discharge of the water after it is treated, according to Patchett, project manager with Burns & McDonnell. Nutrients are defined as phosphorus and nitrogen compounds.

“In the state of Illinois, for phosphorus, the state has stated that if you build a new plant, your phosphorus limit will be 1 milligram per liter,” Patchett said. “If you expand your plant by an amount of 1 million gallons per day or greater, you will get a phosphorus limit of 1 milligram per liter. If your plant is discharging to an impaired lake or stream, one milligram per liter or lower will be applied to your plant depending on the water quality.”

One option for removal of nitrate and phosphorus would be biological, where bacteria or bugs that could treat the plant would facilitate the conversion of the nutrients into such a state that they could be removed.

“Your current plant uses a trickling filtering process that has very limited nutrient removal abilities,” Patchett said. “The type of plant you have here right now is not designed to remove a lot of nutrients. It was not designed to meet these new standards that are being considered.”

The village received a new discharge permit from the IEPA in January, which includes a 1 milligram per liter phosphorus limit.

“The reason for that limit was they saw algae in the stream where the plant is discharged,” Patchett said. “Currently, the Rantoul plant ... is rated for 4.33 million gallons per day. What the plant does is it must reduce levels of solids, organic matter, ammonia and provide disinfection prior to discharging into the stream.”

Patchett said ammonia, nitrate and total nitrogen are regulated. Ammonia is regulated because it can kill fish while nitrate can affect drinking water. Total nitrogen is regulated so fertilizer is not developed, which would essentially promote algae and other plant growth, which would impair the stream where the discharge takes place.

The second removal option is chemical addition, which is primarily used for phosphorus removal to convert phosphorus into a solid form. The total cost of that would be $950,000.

“This typically, for a plant like the village of Rantoul, is a little less expensive and an easier solution to implement,” Patchett said. “When we look at our recommendations for phosphorus removal, phosphorus removal is needed to meet your permit requirements. Chemical salts would be added to precipitate phosphorus. There is pilot testing currently (underway) that would allow the village to enhance efficiency and reduce chemical demand.”

Patchett said the Rantoul plant has one anaerobic digestor, which “is basically one tank that digests sludge.”

“We recommend that the village consider the installation of the second anaerobic digestor,” Patchett said, which would come at a cost of $3.7 million.
Patchett said the potential exists in the future for nitrogen limits, for which the plant currently does not have a system.

“If you were going to design a plant for removal of ammonia and nitrogen compounds, you would not design that type of plant,” he said. “You would want one that has multiple digestors in it. I think the point there would be is if nitrogen limits were to come down the road, you would be looking at needing ... a new process treatment.”
The preliminary cost for that project would be $10.9 million. That cost would be in addition to the combined $4.6 million cost of the chemical addition and second anaerobic digestor.

“What I should clearly state to you folks is that this is not imminent,” Patchett said. “This is not on the radar to happen, but again, as part of the study, we were asked to look at what could happen if regulations were imposed in the future. This is what could happen, but we do not see it happening in the near or immediate future. There is a potential that it would never happen. There is also the potential that the IEPA could come out and push this.”

Trustee Roger Jones asked what Patchett meant by immediate future, and Patchett said in the next five or 10 years.

“Regardless of the main treatment process that you would have, be it the trickling filters or an activated sludge, you need the digestor,” said Craigmile, a senior wastewater engineer. “That would not be a lost cause. The IEPA requires that if you have an activated sludge process that does remove nutrients biologically, you also need the chemical feed system as a backup. There’s no part of what we’re recommending that would be a lost cause.”

Mayor Neal Williams asked if the IEPA would provide any assistance in regards to cost of the potential construction project. Patchett said no grants are available for the project.

Patchett said his firm did meet with the IEPA as part of the study. The IEPA recommended Rantoul only provide nutrient removal facilities that needed to meet the permit limits that came up in January.

“From the IEPA’s perspective, they were not seeing anything in the near future,” Patchett said. “With that being said, our recommendation would be to provide a chemical feed system to remove phosphorus and to provide a second anaerobic digestor to address additional solids and management issues.”
Patchett said the current digestor works at about 90 percent capactiy, and this is before any additional chemical feed systems or any significant future development to the village.

“Whether you do it now or you do it later, it’s something you should think about doing,” Patchett said of the second digestor. “You’re kind of running right at that margin as we speak. It’s something we think you should consider seriously going forward with respect to any plant upgrades. If you make that particular upgrade, and you put in the chemical feed system, I would say that your plant should be in pretty good shape for an extended period of time.”



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