The wastewater treatment process begins with preliminary treatment where all influent waste flows into a large underground tank called a wet well. There are six influent pumps, altogether designed to pump a total of 85 million gallons per day.

The first step in this treatment processing is wastewater screening. KRMA has two barscreens with 1/2 inch spaces between the bars. Large debri, such as sticks, rags or plastic bags are caught on the screen and augered to a dumpster.

The wastewater next flows into the grit tanks where air is pumped into the wastewater to keep the organic material in suspension, while the inorganics such as sand and grit are settled out and conveyed to another dumpster. These dumpsters are routinely hauled away for landfill disposal.

Next, the wastewater travels to the primary clarifier tanks where floatable and settleable solids are removed. The primary clarifiers remove 20-25% of total solids and organic material.

The solids removed are pumped to the sludge mixing tanks, while the wastewater continues on to secondary treatment.

The first step in secondary treatment is biological treatment in six aeration tanks. Here air is diffused into the wastewater to enhance the growth of microorganisms. These microorganisms convert the organic material into more microorganisms.

In the next step of secondary treatment the wastewater flows into one of four secondary clarifier tanks. These circular clarifier tanks remove floating and settleable solids, which consist mainly of microorganisms. The majority of the microorganisms removed are returned to the aeration tanks for reuse, while a small amount is wasted to the sludge mixing tanks.

The final treatment process is the addition of chlorine gas to the treated wastewater to kill all remaining organisms.

Sodium Bisulfate is then added to remove any remaining chlorine which could be harmful to the river's ecosystem.

All of the treated waste solids, which are removed from the primary and secondary treatment processes, are first pumped into two sludge mixing tanks.

After mixing, the raw sludge is pumped into two Dissolved Air Floatation Thickening of DAFT tanks. Here air is introduced in solution into the sludge, causing the solid material to float on top of the water.

The sludge is taken off the top and the water is returned to the preliminary influent wet well for treament.

Next, the sludge is pumped into one of three primary digesters for anaerobic digestion. Here the sludge is mixed and the temperature maintained at 95 deg. F. This facilitates anaerobic bacterial growth, which breaks down the organic material further producting methane gas.

The methane gas is collected and burned in two onsite generators to produce electricity to partially power the plant. Sometimes excess gas is produced and must be burned off with the gas flare.

Approximately 30% of the plant's power usage comes from the digester gas, while another 50% comes from the City of Kankakee's hydroelectric plant located upstream on the Kankakee River. The remaining power is purchased from Commonwealth Eddison.

After digestion, the sludge is pumped to the sludge thickening building, where it is thickened before being stored. Here it is pumped onto two gravity belt thickeners, where the sludge is spread on conveyor belts, and polymer is added, allowing the sludge and water to seperate.

After the water is drained, the thickened digested sludge is collected in a hopper, from where it is pumped into one of four sludge storage tanks. The sludge is stored here until it is hauled away to be used as a soil additive on farm fields in the area.

Certain stages of the treatment process release foul odors, which can carry throughout the surrounding area. KRMA has three odor control systems, installed at the highest odor emitting treatment processes.

There are two biological odor control systems, which treat the odorous air by blowing it through bacteria laden organic media. These bacteria eat the organics material in the air, eliminating the odor.

In addition, there is one chemical odor control system which treats the air with the addition of chemicals that react with the odorous material and chemically break it down, eliminating the odor.