A wastewater treatment plant’s aeration system is the heart of the biological treatment of wastewater and is often the largest consumer of energy on site. The City of Elmhurst Water Reclamation Facility air mains had developed leaks over time, and the aeration blowers providing air were an older technology (multi-stage centrifugal blowers) that were inefficient compared to newer technologies. The City recognized that an update was needed in order to realize energy savings and maintain this vital infrastructure. Thanks to grants from the Illinois Clean Energy Community Foundation and the Department of Commerce and Economic Opportunity, totaling about $800,000 and awarded in 2014 during project initiation, the City was able to implement the $1.9 million improvements. These included installing three new, efficient, single-stage centrifugal blowers, as well as new air mains and advanced controls. The controls system is comprised of dissolved oxygen and ammonium probes in conjunction with air flow meters and motorized control valves. All of these components work together to ensure the aeration system is receiving only the necessary amount of air to treat the incoming waste.
The new system has been serving the process since early March of this year, with full project closeout scheduled for June. Air is no longer lost through aging infrastructure and it is also provided through more efficient means with optimized controls. Power monitoring, completed pre- and post-project, showed that the plant will save about 1,700,000 kWh annually, a 63% savings. This equates to saving the City $85,000 per year.
This improvement project, which involved a building retrofit as well as maintaining plant operations while switching aeration tanks to new air mains, presented unique challenges that required unique solutions. Coordination and teamwork between the City, Engineer (Baxter & Woodman, Inc.) and Contractor (Boller Construction) was imperative to the success of the project. Its completion is just one part of ongoing maintenance and improvements to ensure the wastewater treatment plant can serve its purpose for the City. During this project, the City WRF staff maintained 100% effluent compliance, a true team achievement.