Treating Wastewater
The water reclamation facilities, staffed by state-certified operators, use an array of physical, biological and chemical processes to treat wastewater. The facilities discharge to the Cache la Poudre River and Fossil Creek Reservoir. Effluent meets and exceeds state and federal regulations for water quality. The removed solids in the treatment process are digested to meet strict state and federal standards for organic and pathogen removal. These biosolids are dewatered and applied as a beneficial amendment at Meadow Springs Ranch.
In accordance with the City Environmental Policy (PDF 458KB), the Drake Water Reclamation Facility has implemented an Environmental Management System (EMS) to ensure we continue to meet and exceed regulatory requirements, prevent pollution in operations and foster a culture of continuous improvement related to environmental performance. We are currently seeking ISO 14001 certification for EMS.
Awards
- Colorado Department of Public Health and Environment Environmental Leadership Program Silver Partner
- USEPA National Outstanding Plant Operations and Maintenance
- National Outstanding Pretreatment Management
The Mulberry Water Reclamation Facility project was completed in March and fully operational as of July 2011. The treatment process incorporates fine screening, three-stage biological nutrient removal with a state-of-the-art aeration process, biological odor control and pumping. The plant utilizes ultraviolet disinfection, a more sustainable alternative to traditional disinfection methods.
Wastewater Treatment Process
Click on the numbers located on the map to read a description of each major section of the process.
Collection System
The wastewater collection system is a network of underground pipes that collects wastewater from homes, businesses and industry. The pipes carry the waste to one of the Water Reclamation Facilities. The system is designed to flow at a velocity of approximately two feet per second to keep organics from settling in the system.
Pretreatment
Wastewater from some businesses and industries contains pollutants that wastewater treatment facilities are not designed to treat. Before wastewater of this type can be discharged to a wastewater treatment facility, it must be pretreated. This process reduces pollutants to levels that assure wastewater treatment facility operation and biological processes are not affected.
Bar Screens and Grit Removal
Bar screens trap and remove coarse debris as wastewater enters the treatment facility. This prevents mechanical damage or clogging of pipes, pumps and other equipment.
After passing through the bar screen, wastewater enters a grit basin where the flow is slowed allowing sand, rocks and other heavy particles to settle. Grit removal protects plant equipment and prevents loss of capacity due to solids accumulation.
Material from the barscreens and grit basins is deposited in the Larimer County Landfill after being washed and dewatered.
Primary Clarifier
In the primary clarifiers, wastewater is slowed to allow organic solids to settle. The solids are pumped to the anaerobic digesters and floating scum and grease are skimmed off the top.
Biotower
In the biotowers, wastewater from the primary clarifiers is applied over plastic or rock media. A biological process takes place that transforms the organic material into slime. As the slime grows, it becomes heavy enough to fall off and it is carried to the intermediate clarifiers.
Intermediate Clarifier
Slime from the biotowers settles in the intermediate clarifiers before it is thickened and pumped to the anaerobic digesters. Water from the clarifiers is carried to the aeration basins.
Aeration Basin/Secondary Clarifier
Adding oxygen in the aeration basin speeds up the bacterial growth which removes organic wastes. The solids and water from the aeration basin then flow into the secondary clarifier. The solids settle out and are returned to the aeration basin. The clear water flows on to the disinfection process.
Sludge Thickening
Solids are mixed with fine air bubbles so they can be skimmed off the surface. The thickened sludge is then pumped to the anaerobic digesters.
Anaerobic Digester
This process reduces the pathogens and odors of the incoming sludge. The anaerobic digester mixes and heats the sludge in an enclosed tank without oxygen. Anaerobic bacteria break down organics and produce methane gas. This gas is burned in boilers to supply heat for the process and for facility buildings. After 30 to 60 days, the sludge is ready for dewatering.
Dewatering and Beneficial Use
Liquid biosolids have the water taken out through chemical and physical processes. The resulting solid material is trucked to the Meadow Springs Ranch and applied as a soil conditioner.
Disinfection
At this point in the process the water is clean, but must be disinfected to remove disease-causing pathogens.
Discharge
Now that the water is clean and safe for the environment, it is discharged back into the waterways. Water from the Mulberry facility is discharged directly into the Cache la Poudre River. The Drake facility mainly discharges water into the Fossil Creek Ditch to be used by farmers for irrigation. Water also goes to Rawhide Power Plant as part of a reuse agreement.
