How do treatment plants protect our water?
Wastewater treatment plants:
* Remove solids, everything from rags and plastics to sand and smaller particles found in wastewater; * Reduce organic matter and pollutants--naturally occurring helpful bacteria and other microorganisms consume organic matter in wastewater and are then separated from the water; and, * Restore oxygen--the treatment process ensures that the water put back into our rivers or lakes has enough oxygen to support life. Where does wastewater come from?
* Homes--human and household wastes from toilets, sinks, baths, dishwashers, garbage grinders, clothes washers and drains. * Industry, Schools, and Business--chemical and other wastes from factories, food-service operations, school activities, hospitals, shopping centers, etc. * Storm Water Infiltration and Inflow from Runoff and Groundwater--water that enters the sanitary sewer system during a storm, as well as groundwater that enters through cracks in sewers. The City of Columbia has one set of sewers for wastewater from homes and businesses (sanitary sewers) and a separate system for storm water runoff.
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. How does our wastewater treatment plant work?
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." Wastewater treatment basically takes place in three stages: 1. Preliminary & Primary treatment, which removes 40-60% of the solids. 2. Secondary treatment, which removes about 90% of the pollutants and completes the process for the liquid portion of the separated wastewater. 3. Sludge (biosolids) treatment and disposal.
Preliminary & Primary Treatment
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...