The Water Reclamation Facility for the City of Plano is located on the southeast side of town, next to Foli Park. The present facility was last expanded in 2006 at a capacity of 2.44 million gallons per day.
The City of Plano's Water Reclamation Facility has a long history of providing excellent service to its 11,000 residential customers and various industries. In 1993, the facility was nominated for plant of the year by the Environmental Protection Agency. In 2003, the receiving stream - Big Rock Creek - had its rating elevated to a Class A stream by the Illinois Department of Natural Resources. This is the highest rating available. Several endangered aquatic species have begun to proliferate near the facility, lending to the high quality of treatment being provided by the City of Plano.
The American Council of Engineering Companies of Illinois awarded Deuchler Engineering Corporation and the City of Plano with an Honor Award for the 2004 Wastewater Treatment Plant Improvements Project. Through working with the public and local environmental groups, the treatment plant expansion project demonstrated innovative applications of existing and new technologies, and included sustainable design elements while protecting the water environment.
The new expansion of the facility includes biological nutrient removal and ultraviolet disinfection. These additions will further improve the treated wastewater that leaves the plant, insuring the City's commitment to protecting the environment and our natural resources.
The superintendent of the plant is Darrin Boyer who has over 41 years experience in the field, with 30 years at the Treatment Plant. He holds a Class A Water Certification and a Class 1 Wastewater Certification, which are the highest levels available in the state. In 2010, Darrin received the William D. Hatfield Award from the Water Environment Federation and Illinois Water Environment Association. The Hatfield Award is given to operators of wastewater treatment plants who through their outstanding performance and professionalism deserve commendation.
Don Haggard is also a full-time employee, starting over 16 years ago. Don currently acts as a senior operator of the plant.
Additional operations staff include Jamie Klein and Logan Atkinson. Jamie has been with the city for 13 years with Logan starting this year.
Influent wastewater enters the treatment plant on the west side of the property. A Parshall Flume is used to acurately measure flows entering the facility.
At the head of the plant where wastewater flows enter, a Septic Receiving Station has been installed to readily accept septic waste from private entities. Septic waste contains high levels of volatile fatty acids (VFAs). These VFAs help to increase the efficiency of the treatment plant's phosphorus removal process. Not only does this service allows the plant to operate at an elevated efficiency but the revenue it generates helps to reduce the monthly billing for the public.
Once the influent flow is measured, it is split between two concrete channels as it enters the Bar Screen Building.
The Bar Screens are used to remove plastics, rags, and large debris to prevent damage and clogging of downstream equipment and piping. The screens extend down into the two concrete channels and rotate to pull debris out of the water as it passes through. The City of Plano has two continuous self-cleaning screens. One is four foot wide and the other is two foot wide. A third concrete channel was included with the design of this building to allow for an additional bar screen; should the plant require it in the future, as the city's population increases.
From the Bar Screen Building, the wastewater passes into two Aerated Grit Tanks. This system helps to remove heavy particles, such as sand or gravel, that were not caught by the bar screens upstream. The system functions by introducing air near the bottom of the tank. As the air rises to the surface, it creates a circulating current within the water. As heavier particles rise, they get pushed to the outside of the tank and eventually settle to the bottom where they are collected and pumped out. Lighter particles are suspended and eventually are carried out of the tank and further into the treatment plant.
Heavy particles collected from the grit tanks are pumped back to the Bar Screen Building where they are concentrated using a hydro-cyclone prior to washing. Debris collected by the bar screens and concentrated grit is compacted in the Bar Screen Building and conveyed to a dumpster before being hauled off-site to a landfill.
After wastewater leaves the grit collection system, it enters two, 95X30 foot concrete Equalization Tanks. These tanks are designed to store the influent wastewater as it enters the treatment plant and release it at a fixed flowrate. This constant flowrate helps to provide a steady state condition for the treatment plant's biological process.
The Equalization Tanks each have three Mechanical Mixers installed. These mixers help to maintain a consistent suspension of waste particles within the water. Within these tanks, fermentation occurs providing additional VFAs for the downstream phosphorus removal process.
From the Equalization Tanks, water flows to the BNR process. In the BNR process, organic material is converted by bacteria in suspension to inert products like carbon dioxide and water. Ammonia which may be toxic to fish and macroinvertebrates is also converted into nitrate and then nitrogen gas. Phosphorus is also removed biologically. The removal of nutrients helps Big Rock Creek to be an outstanding water resource.
A portion of the biological process requires air. A high-speed turbo blower provides air to the bacteria so they can metabolize the waste.
Fine bubble air diffuser pipes are installed at the bottom of each tank and bubble air slowly up to the water's surface. The oxygen in the air dissolves in the wastewater, allowing the biological process to thrive.
Five concrete Selector Tanks are the first stage of the aeration process. These smaller tanks operate in series and can be configured to operate anaerobically (complete absence of oxygen) for biological phosphorus removal, anoxically (absence of free oxygen molecules) for denitrification, or aerobically (presence of free oxygen molecules) for carbonaceous removal of nitrification.
A jet aeration system was utilized in the selector tanks because of the systems excellent ability to rapidly mix and the ease of adding air. By simply turning a few valves, the plant operator can change the process and modify the biology in the tanks.
An ancillary component of the treatment plant, but just as important to the process, is the Main Blower Building. Equipment here provides the air required by the BNR process.
The Blower Building houses three, 150 horsepower (HP) centrifugal blowers capable of delivering 2,000 cubic feet per minute(cfm) and one 75 HP turbo blower with a maximum output of 1,100 cfm.
The next stage of the treatment process is Final Clarification. The Plano treatment plant utilizes two, 75-foot diameter, clarifiers for the purpose of settling bacteria. A portion of the settled bacteria can be returned to the process to metabolize more waste while others are wasted from the system to maintain a mass balance.
The key to Final Clarifiers, sometimes referred to as Secondary Clarifiers, is to fill the clarifiers at a rate slower than the particles are able to settle. This leads tow aste particles, called "sludge" colleting at the bottom.
A portion of the sludge, that already contains healthy microbes, is pumped to the Aeration Tanks in order to seed the growth of new microorganisms. The biology that is wasted is pumped to the Aerobic Digestors were the volume is reduced by biological activity.
Water that is able to overtop the clarifier walls is about 90-95% clear of impurities. This water is collected in a channel that surrounds the clarifiers and is piped to the final phase of treatment, Ultraviolet (UV) Disinfection.
Before reaching the Aerobic Digestor, sludge passes through a Rotary Drum Thickener (RDT) to increase the solids content and reduce the volume of sludge that is treated in the Digestor. The RDT is capable of reducing the sludge volume by up to 90%, with a capture efficiency of 98%. From here, the sludge is pumped to the Aerobic Digestor.
The treatment plant utilizes a 75-foot diameter tank that has been converted to three Aerobic Digestor zones. Bacteria here convert remaining organic matter mainly into carbon dioxide and water. As the organic matter is used up, the bacteria begin to die and are used as a food source by the remaining bacteria species, further reducing the volume of the sludge.
Similar to the BNR process, aerobic digestion requires air for the bacteria to metabolize organic matter. Two, 175 HP, 2,280 cfm Hybrid Blowers are used to provide air to this system.
From the Aerobic Digesters, the sludge is pumped to a Sludge Centrifuge. The centrifuge uses a fast rotation to separate the sludge from remaining liquid still present. While the water is sent back to the head of the plant, dried sludge is stored before being hauled off-site to be land applied on farmlands.
Before leaving the treatment plant, wastewater from the final clarifiers passes through an array of sixty, 120-watt, ultraviolet (UV) lamps. Ultraviolet disinfection is a chemical-free process that neutralizes microorganisms as they pass by submerged ultraviolet lamps. The sterilized microorganisms aren't removed from the water. However, they no longer present a danger to humans.
The treated wastewater as it leaves the plant is referred to as "Effluent". At this point, the effluent is safe to return to the environment.
The treated water is conveyed through a 30-inch pipe, under the roadway to the Cedardell Golf Course irrigation pond, where it is land applied to keep the course looking green-even in the hot summer months.
Effluent that is not utilized by the neighboring golf course feeds back into the Big Rock River right next door.
Efforts to be at the forefront of environmental sustainability has led the city to install an impressive sprawling solar panel array at their treatment facility.
With a total of 3,367 panels, the system covers 4.5 acres and is capable of producing 1.3 megawatts (MW), or 1,300,000 kilowatt hours (KWH). This provides an annual savings of $35,000 as well as a carbon offset equivalent to 2,632,663 miles driven, 110,338 gallons of gasoline, or 1,168,592 pounds of coal burned!