The Metropolitan Water Reclamation District of Greater Chicago’s (MWRD’s) Kirie and Egan water reclamation plants (WRPs) are taking inventory of energy usage and finding innovative ways to cut costs.

Under the ComEd Strategic Energy Management (SEM) program created for qualified industrial customers, the MWRD has worked with Cascade Energy to develop new efficiencies that cut energy consumption. But unlike a major retrofit, curtailing energy, implementing new technology or relying on new sources of energy, this detailed exercise has had plant operators and engineers researching and meticulously examining about 80 different treatment procedures to figure out how they can reduce energy demand.

“The Strategic Energy Management program has been an educational and rewarding experience that allows us to work toward incentives that protect our taxpayers but also shows us a route to cut back our energy bills by implementing energy saving practices at our everyday operations,” said MWRD President Kari K. Steele. “Thank you to our hard-working Egan and Kirie plant staff for shining a less-energy intensive light on how we can improve our operations.”

Staff worked as a team to review where they can increase efficiencies while minimizing disruptions in other processes. Along the way, they found leaks, made repairs, installed new pumps and other equipment. The study has served as a catalyst for productive and efficient changes.

From April 2022 through 2023, the MWRD’s Egan facility in Schaumburg saved more than 1 million kilowatt hours (kWh) of energy for a savings of $96,000, in addition to an incentive of more than $40,000 the MWRD received. That is equal to 759 metric tons of carbon dioxide avoided on completed projects, or the equivalence of carbon dioxide emissions from 97 homes, the greenhouse gas emissions of 166 passenger vehicles, or the amount of carbon sequestered in 900 acres of forest.

At the Kirie facility in Des Plaines, in 2023, the MWRD generated a savings of 617,079 kWh, an energy cost savings of more than $55,000, not including almost $20,000 in incentives earned. This savings is equivalent to 437 metric tons of carbon dioxide, the carbon dioxide emissions from 55 homes, greenhouse gas emissions of 97 vehicles, or the amount of carbon sequestered in 552 acres of forest. 

The MWRD is in the process of completing a multi-year study to formulate conceptual plans at achieving energy neutrality by 2035. The MWRD will meet these goals by implementing efficiencies to reduce energy consumption while also increasing the use of renewable energy, including biogas that the MWRD produces in-house through its digesters. The MWRD uses the biogas to heat buildings and the digesters at its water reclamation plants. But plants like Kirie do not manage digesters, so the challenge to find efficiencies is even more challenging.

The SEM program engages MWRD staff over several years to find and complete energy savings projects, track energy performance, and engage their peers in saving energy every day. Cascade Energy provides management training for plant staff, technical assistance for identifying and implementing energy projects, coaching and mentoring, and a tracking software program. It all begins with what they describe as a "treasure hunt" which can last days, assessing what processes can be re-examined under an energy-efficient focus. Some ideas are implementable while others are not realistic. It's up to MWRD staff to decide what is feasible in the long run.

At the Kirie WRP, this has meant adjusting the run times for fine screens operation, reducing the run time of conveyor belts, cleaning dissolved oxygen probes more often, and further adjusting the set point for dissolved oxygen levels in aeration tanks. This delicate balance requires significant fine-tuning. Operating engineers and treatment plant operators consider a variety of measures, while also dealing with changing temperatures and flows, so as not to upset the carefully maintained population of microorganisms that require oxygen. It is this critical microbial activity that helps the MWRD break down solids and remove soluble organics, ammonia and phosphorus, but they also require intensive energy usage from oxygen needs. 

Energy demands present challenges for wastewater treatment. Electricity alone can make up to 25 to 40 percent of a wastewater treatment plant’s annual operating budget and make up 15 to 30 percent of a given municipality’s total energy bill, according to the U.S. Department of Energy. This energy demand is expected to grow over time, driven by population growth, increasing amounts of water to convey during major storm events and more stringent water quality requirements that WRPs have to meet. Most of the electricity used at the MWRD is used by blowers to provide aeration in the wastewater treatment process (46 percent) followed by wastewater pumping (32 percent), and treatment of solids (15 percent).

At the Egan WRP, staff went straight to the source of the major energy consumer and focused on how they could improve blower operations by gradually trimming dissolved oxygen levels in all the aeration tanks when ammonia was not a concern. Over time, they were able to consistently use an intermediate blower using 1000 horsepower (HP) instead of the large blower (1500 HP). 

"We thank our staff at the Egan and Kirie water reclamation plants for their diligent efforts, documentation and research to refine and retool our treatment operations to find efficient ways to cut costs and reduce energy usage," said MWRD Commissioner Eira Corral Sepulveda. "This Strategic Energy Management program with ComEd and Cascade Energy lays the groundwork to discover more savings at all of our facilities."

Following the successful pilot programs at Egan and Kirie, the MWRD is planning a similar study at its O'Brien WRP in Skokie, which can treat up to 450 million gallons of water per day. This collaboration between the MWRD and Cascade Energy is expected to continue producing multiple benefits.

“As a member of the energy coaching team collaborating with MWRD, I’m thrilled to see their commitment to the ComEd Strategic Energy Management program. I’ve had a front-row seat to the dedication and enthusiasm displayed by each MWRD facility involved,” said Strategic Energy Management Coach Joan Gary of Cascade Energy. “This program is voluntary and requires significant resources and commitment to be successful. MWRD's savings speak volumes about the organization's dedication to sustainable practices that directly benefit the community.”