Nutrient runoff: How state is helping suburban sewage plants better reduce pollution in waterways

Excess nutrients from runoff of fertilizers used on suburban lawns and golf courses, along with waste from our daily lives, can find their way into our waterways, leaving behind harmful toxins and bacteria.

It's part of a problem called nutrient loss, one of the most serious pollution threats in the U.S., causing a Rhode Island-sized dead zone in the Gulf of Mexico, poisoning local lakes and streams, and creating health problems for people and domesticated animals.

This year, Illinois lawmakers are considering how to best direct state resources to help reduce nutrient runoff. They're focusing particularly on farms, but they're also targeting runoff in metropolitan areas including suburbs, such as when heavy rains wash nutrients off lawns into nearby waterways, polluting them, or when wastewater in sewer systems is not adequately treated before it flows into natural bodies of water like creeks.

The state aims to reduce total nitrogen and phosphorus loss by 45%, with 15% of nitrogen and 25% of phosphorus reduced by 2025. And local water treatment plants are part of the plan. It's already started in DuPage County.

Water treatment facilities are regulated by the United States Environmental Protection Agency. The Clean Water State Revolving Fund, overseen by the Illinois EPA, provides low-interest loans through the Water Pollution Control Loan program. The loans may be used to improve the overall operations and water quality of treatment plants.

In March 2021, construction at DuPage County's Nordic Wastewater Treatment Plant, which serves parts of Itasca and Addison and surrounding areas, began after it received about a $10 million loan from the program.

Stan Spera, financial administrator for DuPage's public works department, said that out of the three wastewater facilities in DuPage County, the Nordic plant was "in need of major, major upgrades."

Improvements will be made to the site piping and raw sewage pumping and screening structure, along with the overall operations structure and process of treating the water in hopes of improving water quality. Spera said the repayment period is going to be about 20 years.

To ensure the water is safe before being pumped from wastewater facilities into waterways, larger and dense material, such as plastic, rocks or glass, are removed first. Smaller materials such as food bits or fecal matter are then removed through gravity separation. The state is making headway on its goal to reduce nutrient discharge from wastewater treatment facilities. From 2019 to 2020, funding tripled for investment in water treatment, resulting in more than $200 million in investment for improvements at wastewater plants. And clear guidance was in place to help wastewater operators understand what improvements needed to be made and how to get funding, according to the Illinois Nutrient Loss Reduction Strategy Implementation Biennial Report. Meanwhile, the DuPage Forest Preserve has found ways to treat harmful blooms of cyanobacteria, or blue-green algae. Blue-green algae forms when heavy rains wash nutrients, such as nitrogen and phosphorus, into water.

Although blue-green algae is a natural part of the aquatic environment, in warm water it can reproduce quickly, causing thick layers on the surface.

A diffused aeration system was installed in Herrick Lake that helps circulate water and increases oxygen, which hinders algae colonies. The aeration system also increases aerobic respiration of dead plant and animal materials instead of leaving them for uptake by algal species.

Buffer zones are used along the lake to create a break for the overflow "that helps settle out nutrients and particulate solids before they're able to get in the (body of water)," said Grigas, an ecologist at the DuPage Forest Preserve.

Rick Manner, executive director at the Urbana-Champaign Sanitary District, says depending on the type of treatment plant, the extent to which nitrogen and phosphorus can be reduced varies, from 60% to 90%.

The Urbana-Champaign district includes a sanitary sewer water treatment facility that discharges about 22 million gallons a day and serves about 200,000 people. After sewage reaches that facility, Manner said, "bugs," a mixture of microbes, are grown, attach to particles and reproduce to consume waste.

The process takes about 12 hours. The "bugs" prevent growth of bacteria and other microbes when the water is pumped into creeks.

Manner said that since the sewers are more polluted and dirtier, it's unsuitable for waste to be drained back into the waterways directly.

"That's why our treatment plant is here, to treat it to the level that makes it legal and appropriate to go into a creek," Manner said.