chapter 22 Flashcards
(76 cards)
Why is water treatment essential for public health?
Water can be a source of infectious diseases and chemical intoxications, so ensuring purity is crucial.
What are the main goals of water treatment?
To remove pollutants and ensure water is safe for consumption and use.
How are microorganisms used in water treatment?
Microorganisms help to identify, remove, and degrade pollutants in water.
What is sewage?
It includes domestic sewage and liquid industrial waste that must be treated before disposal.
What is the role of microbes in wastewater treatment?
Microbes are used on an industrial scale for bioconversion of pollutants in wastewater.
What other treatments are included in wastewater treatment?
Physical and chemical treatments are also used in conjunction with biological processes.
What is effluent water?
It is the treated wastewater, suitable for release into surface waters or drinking water purification facilities (but not for direct drinking)
What are the goals of a wastewater treatment facility?
Reduce organic/inorganic materials and eliminate toxic substances.
How is treatment efficiency measured
By the reduction in biochemical oxygen demand (BOD).
What does BOD measure?
The oxygen consumed by microbes to oxidize organic/inorganic matter.
What is wastewater treatment?
A multistep process using physical and biological methods.
What is involved in primary treatment?
Physical separation to remove solid and particulate materials.
What is secondary treatment in wastewater treatment?
A biological process that removes remaining organic material after primary treatment.
What is anoxic secondary treatment?
A process where microbes carry out digestive and fermentative reactions under anoxic conditions.
Where does anoxic secondary treatment take place?
In large enclosed tanks like sludge digesters or bioreactors.
What is aerobic secondary treatment?
A process where microbes perform digestive reactions under aerobic conditions to treat water with low organic material.
What are the most common aerobic secondary treatment methods?
Activated sludge and trickling filters.
What happens in the activated sludge process?
Wastewater is mixed and aerated in large tanks, promoting bacterial growth.
What role do slime-forming bacteria play in the activated sludge process?
Bacteria like Zoogloea ramigera grow and form flocs to treat the wastewater.
What is done to the effluent after secondary treatment?
Most treatment plants chlorinate the effluent to reduce biological contamination.
What is tertiary treatment?
Additional physicochemical or biological treatment to further process secondary effluent.
What are the goals of tertiary treatment?
Remove organic matter and suspended solids
Reduce inorganic nutrients (phosphate, nitrate, nitrite)
Degrade toxic materials
Why isn’t tertiary treatment widely adopted?
It is the most complete method but costly.
What is an example of tertiary treatment?
Phosphorus removal is a key example.