Wastewater treatment has several stages:
The first stage of the treatment process is called “Headworks,” or preliminary treatment, and uses bar screens and grit removal tanks to eliminate large floating debris and grit.
The second stage is called the “Primary” treatment process and is responsible for the removal of nearly 70 percent of suspended solids and 50 percent of organic matter by means of liquid solid separation in a quiescent pass through tank called a clarifier. The solids, known as “Primary Sludge,” are collected off of the bottom of the clarifier and pumped to a thickening clarifier to remove more clear water. The water that flows out of the tank, into a trough, and to the next stage is called “Primary Effluent.”
The third stage of treatment uses a biological process, known as activated sludge and is considered the “Secondary” treatment process. This process uses aerobic microorganisms to break down organic matter, and chemical constituents of wastewater. These “bugs” gather in colonies and clump together, settling in large tanks called “Secondary” clarifiers.
The fourth stage of treatment utilizes filters that allow 85 percent to 95 percent clean water to pass through a fine sand bed called “Sand Filters” in order to remove minute particles, or remaining suspended solids, this process is known as “Tertiary Treatment.”
The fifth stage of treatment allows the effluent to pass through channels containing ultraviolet light bulbs that sterilize the fecal bacteria, otherwise known as “Pathegenic Bacteria.” These ultra violet light bulbs kill the fecal bacteria, prohibiting them from reproducing. The final effluent is then discharged into the East Branch of the DuPage River.
The solids that are separated in the two different stages of treatment (Primary & Secondary) are combined in a process known as “Anaerobic Digestion.” This process utilizes microorganisms that break down approximately 60 percent of the organic matter, reducing the amount of disease causing bacteria to a level that is permitted by the federal and state governments. The solids are pumped from these tanks to a process called “Sludge Dewatering” where polymer is added to the sludge so a machine can squeeze a substantial amount of water from the solids through a porous belt. This process creates a solid material with the consistency of silly putty to be hauled to land application as fertilizer. Wastewater treatment is 100 percent reuse, and with cooperation of state and federal agencies, this industry continues to make monumental strides in protecting our rivers, lakes, and streams.