Technical lessons
Wastewater Treatment operator lessons
Wastewater treatment lessons explain the biological, physical, chemical, and process-control concepts operators use to clean used water before discharge or reuse.
Lesson 1
Activated Sludge Process
Activated sludge uses microorganisms, oxygen, mixing, and settling to remove organic matter from wastewater.
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Lesson 2
BOD and COD
BOD and COD are oxygen-demand tests used to estimate the strength of wastewater and treatment performance.
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Lesson 3
Sludge Volume Index
SVI is a settleability indicator that compares settled sludge volume with mixed liquor suspended solids.
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Lesson 4
Nitrification and Denitrification
Nitrification converts ammonia to nitrate under aerobic conditions; denitrification converts nitrate to nitrogen gas under anoxic conditions.
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Lesson 5
Primary vs. Secondary Treatment
Primary treatment removes settleable and floatable solids; secondary treatment biologically removes dissolved and fine organic matter.
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Lesson 6
Dissolved Oxygen Control
Dissolved oxygen supports aerobic biological treatment but must be balanced against energy use and process needs.
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Lesson 7
Return Activated Sludge
RAS returns settled biomass from the secondary clarifier to the aeration basin to maintain the microbial population.
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Lesson 8
Wasting and Sludge Age
Wasting removes excess biomass and helps control sludge age, solids inventory, and biological process stability.
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Lesson 9
Secondary Clarifiers
Secondary clarifiers separate biological solids from treated wastewater after aeration or other biological treatment.
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Lesson 10
Chlorination and Dechlorination
Wastewater disinfection may use chlorine to reduce pathogens, followed by dechlorination to protect receiving waters.
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