Odors Flashcards
1
Q
What are the primary causes of odors in wastewater treatment?
A
Ammonia and hydrogen sulfide
2
Q
In order of preference, what molecules can bacteria source oxygen from?
A
- Free dissolved oxygen
- Nitrate
- Sulfate
- CO2
3
Q
What is hydrogen sulfide?
A
An inorganic sulfide
Detectable at 0.02 ppm
Dulls olfactory senses
Soluble in both acids and bases
4
Q
What conditions does H2S form in?
A
Anaerobic conditions free of nitrites or nitrates
5
Q
How can you control H2S?
A
Increase pH to decrease H+ concentration
Add oxidative chemicals to prevent formation
Add nitrates/nitrates
6
Q
How does H2S form?
A
Sulfates -> sulfides and H+ -> ionized hydrogen sulfide -> H2S
H2S is released when saturation occurs
7
Q
How does pH impact odors?
A
Elevated pH can inactivate sulfate reducing bacteria and it decreases H+ concentration leading to more HS-
