Wastewater is made up of human and household waste from toilets, sinks, baths and drains. It also consists of chemicals and other waste from factories, food-service operations, shopping centers and many other businesses.
Wastewater generated in Bowling Green and parts of Warren County flows to the wastewater treatement plant via sewer lines. Trash is filtered by bar screens and discarded.
A grit chamber (large tank) slows down the flow of water allowing sand, grit and other heavy solids to settle to the bottom and be removed, preventing damage to pumps and other equipment.
A primary sedimentation tank lets smaller particles settle. Scrapers or other devices collect any remaining solid matter (primarily sludge) plus scum or grease floating on top.
Secondary treatment ensures that a minimum of 85 to 90% of pollutants are removed. An activated biofilter aerates a mixture of wastewater, bacteria and other microogranisms. Oxygen in the air speeds the growth of helpful microorganisms, which consume harmful organic matter in the wastewater.
A secondary sedimentation tank allows microorganisms and solid wastes to form clumps and settle. Some of this mixture, called "activated sludge", can be mixed with air again and reused in the biofilter. Any activated sludge that is not used is sent back to the beginning of the process to be mixed with primary sludge. Primary sludge is then de-watered and sent to the landfill.
Chlorine, a disinfectant, is added to wastewater before it leaves the treatment plant to kill disease-causing organisms. Before disinfected water is discharged, it must be treated to remove chorline so fish and other organisms in the receiving stream are not adversely affected.
After treatment, water is returned to Barren River.
From the late 1800’s until 1935, Bowling Green used a combination storm drainage system and sanitary sewer system. The Whiskey Run Sewer System, as it was known, was an open sewer system that carried sanitary sewer and storm sewer throughout most of Bowling Green directly to Barren River without being treated.
In 1930, despite the Depression, the city hired JN Chester Engineers of Pittsburgh to study the possibility of constructing a sanitary sewer system for Bowling Green. The waterworks committee reported that water was not filtered, and people’s health was in danger. At the time, there was a typhoid epidemic, and the unsanitary disposal of wastewater through the cave system was believed to have been the cause. People dug a hole in their backyard and ran a line to the hole from the house. The sewage drained into the hole and then into Whiskey Run, the cave system, or the ground.
On November 1, 1932, the city approved a $630,000 loan to finance a sanitary sewer system for Bowling Green that would drain into several septic tanks located near natural sinkholes. The project was complete in June of 1933.
The first Wastewater Treatment Plant was built in 1935 on Barren River, near the current wastewater facility. An Imhoff tank, designed as a sedimentation and sludge digestion unit, was the first form of wastewater treatment. Approximately 44.5 miles of interceptor and collector sanitary sewer lines were laid to serve Bowling Green's population of approximately 13,000.
In 1963, a $10 million wastewater expansion took place. The present Wastewater Treatment Plant was constructed, with a plant capacity of 5.2 million gallons per day. Over 60 miles of sanitary sewer lines were laid throughout the city. At the time, there were a total of 8,300 customers.
In October of 1974, a $6 million expansion to the Wastewater Treatment Plant made it possible for 97% of the impurities in the waste stream to be removed; with the completion of this expansion, plant capacity was 8.4 million gallons per day.
In 1993 the Wastewater Treatment Plant was again expanded. This $8.5 million expansion increased plant capacity from 8.4 million gallons per day to 10.6 million gallons per day.
Most recently, the plant was upgraded and expanded in 2012. The treatment process was changed to Sequencing Batch Reactors to achieve better nutrient removal. Cost of the project was approximately $55 million, and capacity increased to 12 million gallons per day. The plant was designed for the easy addition of two more aeration tanks to bring total plant capacity to 15 million gallons per day.
Today, the collection system is comprised of over 260 miles of sewer mains, serving approximately 20,000 customers. There are approximately 75 employees in BGMU's Water and Wastewater departments, and crews are on call 24 hours per day, 7 days a week.