About the author:
John Hinde is the president and owner of Air Diffusion Systems. Hinde can be reached at [email protected].
Minonk, Illinois was founded alongside the construction of the Illinois Central Railroad in 1854. In addition to the railroad, major industries in Minonk’s early history included farming, lumber, and coal mining. Currently Minonk is home to approximately 2,000 people.
The city of Minonk contacted Air Diffusion Systems in 2012 to provide an energy efficient, natural solution to meet new discharge limits of biological oxygen demand (BOD), total suspended solids (TSS) and nutrients without taking the lagoons out-of-service.
ADS designed an aeration system including bioaugmentation using sludge reducing bacteria (SRB). The aeration system services two lagoons and includes 71 fine bubble diffusers and 8 lines of linear aeration tubing. The lagoons were initially dosed with non-pathogenic sludge reducing bacteria (SRB). The ADS engineered aeration system also uses less than 33% of the power required by the old system, providing cost saving opportunities for the community. Due to the improved treatment results and reduced energy consumption, the improvements to the lagoon were funded by the Illinois EPA.
ADS “LTC” disk modules produce over a billion fine bubbles per day and provide ease of installation and maintenance through the use of a work boat to ensure that the lagoons never need to be dewatered.
Header piping and 1-inch feeder tubing lines connect the diffusers to the blower building and air supply, which delivers a total of 656 SCFM of fine bubble diffused, oil-less air to the lagoon system. The ADS aeration equipment installation at Minonk lagoons took place over three days in June 2018.
Floating Baffle Cover
The surface of Lagoon 2 is partially covered by a baffle composed of wind resistant tiles. This baffle reduces the accumulation of suspended solids and algal growth by blocking sunlight. Additionally, the baffle helps to increase the water temperature for proper nitrification conditions.
Sludge Reducing Bacteria (SRB)
The sludge reducing bacteria (SRB) is a non-pathogenic formulation of microorganisms selected for their ability to digest organic matter. Proper application doses of SRB vary for each lagoon system. ADS recommended the application of SRB to supplement the aeration treatment. SRB in an aerobic system provides a highly cost effective and efficient way to reduce unwanted organic matter buildup in lagoon systems. SRB applications provide signification cost savings compared to sludge hauling. Additionally, with proper safety data sheets, SRB application does not require permitting.
Prior to the ADS installation, the Minonk lagoon utilized five 25-hp surface aerators, requiring a total of 125 hp. The ADS Fine Bubble Aeration system is powered by a 41 brake horsepower (bhp) oil-less air supply, reducing the operational horsepower by three times and saving the city of Minonk more than $80,000 annually in energy costs. ADS aeration solutions are unique for each project site, but primarily use two different types of oil-less air delivery systems, blowers and compressors.
At Minonk wastewater treatment plant, both a compressor and blower supply air to the system. Lagoon 1 is supplied oxygen through a 40-hp Inovair Turbo blower, delivering 575 SCFM of filtered oil-free air and operating at 34.7 bhp. Lagoon 2 receives 81 SCFM of air through a 10-hp Bush Mink claw compressor, which operates at 7.0 bhp. Both are oil-less air delivery systems keeping the water free of any air supply oil contamination.
Project Funding
The city of Minonk received complete funding for wastewater treatment plant upgrades from the Illinois EPA. The Illinois EPA Clean Water State Revolving Fund is a federal-state partnership, developed in 1988, to provide communities with low-cost options to finance water quality projects.
Results
After effectively phasing out surface aeration and applying fine bubble aeration diffusion, the wastewater effluent has exceeded the permit requirements for BOD and TSS.
The ADS fine bubble aeration system has had a transformative effect on the treatment at the Minonk, IL wastewater treatment system.
With ADS’ superior oxygenation and mixing, this system has proven to be a low energy solution to treat the Minonk lagoons.
