Columbia's Waste Water Treatment Plant is undergoing significant upgrades in waste water treatment technology and capacity. The project was recently featured in North America Business Review magazine. View the article - by clicking here.
The staff at the Columbia Regional Wastewater Treatment Plant will be happy to arrange a tour for you and/or your group.
Click on the image below to view an aerial photo of the treatment plant (106 kb).
Construction of the Columbia Regional Wastewater Treatment Plant was completed in 1983 and required approximately 200 man-years of effort in moving 600,000 cubic yards of earth and rock (enough to fill Faurot Field to the top of the bleachers), placing 75,000 tons of concrete, installing 40,000 lineal feet of piping with 234 valves, and providing $3 million worth of equipment. The total construction cost for the Columbia Regional Wastewater Treatment Plant was $21 million. An additional $30 million was spent for construction of new interceptor sewer lines to convey wastewater to the new treatment plant. The original plant design capacity was 13 million gallons per day. More than 75 small wastewater treatment facilities throughout Columbia were eliminated by construction of the Columbia Regional Wastewater Treatment Plant.
By 1990, in order to meet the needs of a growing community and to continue the City's efforts to protect streams and groundwater in the area by extending sewers into unsewered developments, it was necessary to increase treatment capacity. In preparation for growth during the next 20 years, the City upgraded the Columbia Regional Wastewater Treatment Plant and constructed a series of wetland treatment units (ponds). The fourth treatment unit was completed in 2001. The design capacity of the Columbia Regional Wastewater Treatment Plant is approximately 20 million gallons per day.
The constructed wetland treatment units are located in the McBaine Bottoms and receive wastewater after it is treated at the original treatment plant. After additional treatment as it flows through the constructed wetlands, the wastewater is discharged to the Missouri Department of Conservation's Eagle Bluffs Conservation Area on the Missouri River.
It's cleaning used water and sewage so it can be returned safely to our environment.
Wastewater treatment plants:
On the average, each person in the U.S. contributes 50-100 gallons of wastewater every day. If you include industrial and commercial water uses, the per person usage of water is as high as 150 gallons per day.
The 16 million gallons per day (average) entering the facility is conveyed by over 635 miles of interceptor sewers, varying in size from 8 inches to 72 inches in diameter. The Sanitary Sewer Maintenance Section is responsible for the maintenance and repair of all public sewer mains and manholes.
The type of wastewater treatment used in the Columbia Regional Wastewater Treatment Plant is called the complete-mix activated sludge process. This is a biological process in which naturally occurring living microorganisms (bacteria, protozoa, tiny plants and animals) are maintained at a very high population level. They quickly consume the dissolved and suspended organic material carried over from the primary treatment of the incoming wastewater as a source of food. This process promotes the formation of biological masses that clump together by adhesion and settle to the bottom forming "sludge."
Sanitary sewers carry wastewater from homes and businesses to the raw wastewater pumping station at the treatment plant. The wastewater flows by gravity, rather than pressurized pipe flow, in the sanitary sewer pipes. Routine cleaning and closed circuit television inspection of Columbia's sanitary sewer lines helps keep the sewer collection system in good shape. Each year new construction in the City of Columbia adds about 10 miles of new sanitary sewer lines and 250 manholes to the sanitary sewer collection system.
Bar Screens let water pass, but not trash (such as rags, diapers, etc.). There are two bar screens located inside the Raw Wastewater Pump Building. The trash is collected and properly disposed of. The screened wastewater is pumped to the Primary Settling Basins. To view pictures of the bar screens before installation, click on the image of the Raw Wastewater Pump Building on the right.
Two Primary Settling Basins allow smaller particles to settle from wastewater by gravity. This primary wastewater flows out to the next stage of treatment. Scrapers collect the solid matter that remains (called "primary sludge"). A surface skimmer collects scum or grease floating on top of the basins.
Two Aeration Basins supply large amounts of air to the mixture of primary wastewater and helpful bacteria and the other microorganisms that consume the harmful organic matter. The growth of the helpful microorganisms is sped up by vigorous mixing of air (aeration) with the concentrated microorganisms (activated sludge) and the wastewater. Adequate oxygen is supplied to support the biological process at a very active level. The ratio of food (organic matter) to organisms to oxygen is continually monitored and adjusted to meet daily variations in the wastewater.
|STEP 2 Two Final Settling Basins allow the clumps of biological mass (the microorganisms) to settle from the water by gravity. 90-95 % of this mixture, called "activated sludge," is returned to the aeration basins to help maintain the needed amount of microorganisms. The remaining 5-10 % is pumped to the anaerobic digester (described later).|
|STEP 3 The final effluent (liquid portion from Step 2) travels through a 2.25 mile long, 72 inch diameter pipeline to WTU-4, the first of the City's four constructed wetland treatment units, in the McBaine Bottoms for further treatment. Cattails planted in these constructed wetland cells (ponds) consume some of the remaining nutrients in the effluent. The wastewater passes through three more WTU's before treatment is completed. This "polished" effluent leaves the City of Columbia's constructed wetlands at the wetlands pump station where it is pumped into the Missouri Department of Conservation's Eagle Bluffs Conservation Area (EBCA), a restored riverine wetland. This "polished" effluent is used as a source of water for the EBCA. For more information about the City of Columbia's constructed wetlands treatment system, click on the image of cattails on the right.|
|All effluent returned to natural bodies of water must meet National Pollutant Discharge Elimination System (NPDES) criteria. The final effluent is monitored daily. In-house laboratory staff performs sampling and analysis for process control and NPDES compliance.|
|STEP 1 The "primary sludge" from the Primary Settling Basins is pumped to the Hydrocyclone Grit Separator where it is spun, thereby separating the inorganic solids (grit) from the lighter weight organic solids. The grit is disposed of in the City landfill.|
|STEP 2 The primary
sludge continues on to the gravity Sludge Thickener where the solids are
concentrated and pumped to the anaerobic digesters. The liquid overflow is returned
to the pump station. Waste Activated Sludge from the Final Settling Basins is
pumped to a Centrifuge (image at right) for further solids processing, then pumped
to the anaerobic digesters.
|STEP 3 Primary and
activated sludges are anaerobically digested (decomposed by bacteria without the
presence of air) in the two-stage digesters. Stabilized sludge has little
odor and conforms to the EPA requirements to further reduce harmful microorganisms.
|Methane gas is produced by this anaerobic digestion and is
used as fuel for an engine-generator providing 240 kW of electrical power used in the
treatment process. Waste heat from the engine is recovered for heating the treatment
plant buildings and to provide heating to improve the sludge digestion process and produce
|STEP 4 Step 4 is the
application of the stabilized sludge (biosolids) onto both City-owned and private farmland
by subsurface injection (plowing).
The biosolids are utilized in an environmentally acceptable manner as a beneficial and valuable fertilizer and soil conditioner. The biosolids applied to all sites are monitored for nutrients, metals, other compounds and fecal coliform bacteria. Soil testing is performed at all sites prior to biosolids application.