There are many steps to treating wastewater:
1. Industry
- Contributes about 20 million gallons of wastewater per day
- Waste stream is stronger than residential
2. Anaerobic Reactors
- Processes 2 million gallons per day of select industrial wastewater
- Organic matter is removed from the waste stream by microorganisms
3. Methane Gas
- Microorganisms produce methane gas as a byproduct
- Gas helps fuel the incinerator and excess is flared
4. Residential & Commercial
- Cedar Rapids, Hiawatha, Marion, Palo, Robins and Linn County residents and businesses contribute about 25 million gallons of wastewater per day
- Wastewater comes from showers, clothes and dish washers, sinks, toilets, and other commercial operations
5. Bar Screen
- Removes large items to protect downstream processes
6. Main Lift
- Pumps wastewater from the collection system to the treatment process
7. Primary Settling
- Waste solids settle to the bottom and are removed
8. Secondary Treatment – Biological
- Wastewater trickles over plastic media where organic matter is removed from the waste stream by microorganisms
9. Advanced Treatment – Biological
- Additional organic matter is removed from the waste stream by microorganisms
10. Settling Basin
- Excess microorganisms settle to the bottom and are removed
11. Advanced Treatment – Ammonia Removal
- Ammonia is removed from a portion of the waste stream by microorganisms
12. Settling Basin
- Excess microorganisms settle to the bottom and are removed
13. Chlorine Disinfection
- Potentially harmful bacteria is killed by adding chlorine
14. Dechlorination
- Excess chlorine is removed from the treated effluent to minimize the impact on aquatic life
15. River Diffuser
- Treated effluent is added to the river through multiple outlets to minimize the impact on aquatic life
16. Waste Solids – Thickening
17. Belt FilterPress – Dewatering
- About 65 percent of the water is removed from waste solids resulting in a thick, dirt-like substance
18. Biological Solids - Thickening
19. Biological Solids – Gravity Belt Thickening
20. Cell Wall Destruction with Temperature and Pressure (LPO)
- Cell walls are destroyed, releasing the liquid stored inside the microorganisms that make up the biological solids
21. Centrifuge Dewatering
- About 60 percent of water is removed from the biological solids by highspeed rotation
22. Solids Blending
- Waste solids are mixed with biological solids to produce a nutrient rich, dirt-like substance, called biosolids
23. Solids Disposal
- 120 tons or more of biosolids produced each day Disposed of onsite through incineration, or offsite through landfilling or land application.
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