Microbes and Water Part 2 Flashcards
Before WW2 what was used instead of chlorine to treat water and why?
Chloramine because it had a reduced “off taste” in the water for instance
-some municipalities are switching to this now
What pathogen is resistant to chlorine?
Giardia
- cycsts are resistant to chlorine and boil orders must be issued
- Water system has to be treated with iodine for several months
How are bad odours, colours and off tastes removed from drinking water?
Through filtration via activated carbon since it is not accomplished by chlorine
What does raw sewage contain?
Pathogenic microbe and a huge BOD demand that must be removed before discharge to natural wateres
Why do we use microbes to treat drinking water?
Using chemicals would be too complex and expensive
-Microbes remove the BOD load from sewage and wastewater
In a simplified model, what is added to a tank to remove organic contaminants?
Bacteria and fungi ar added as well as air to aerate it to stimulate aerobic bacterial growth from the organic matter
What are flocs?
When bacteria and fungi grow in numbers as they consume the organic matter and will form small interlocked masses of bacteria and fungal/bacterial filaments
What is sludge?
When all flocs in a tank settle to the bottom of a tank
What is the point of adding the bacteria to the water?
The water has had all of its soluble organic matter converted into solid microbial mass that can be removed
What is activated sludge process?
Aeration tank is not shut down at any time to keep it continuous in order to treat large amounts of sewage/ wastewater
-fluid containing suspended flocs is constantly pumped out of the tank to a settling tank and it is there that the flocs settle out to form a sludge to be removed
Why is sludge pumped back into the aeration tank in large scale operations?
Sludge pumped back acts as a seed to keep the process working properly.
- prevent the excessive loss of bacterial floc.
- Wouldn’t be enough microbes left to form new flocs, and the BOD would not be removed
What are the primary, secondary and tertiary treatments in municipal wastewater treatment plants?
Primary: treatment to remove greases, oils, debris
Seconday: Activated sludge process to remove soluble organic material
Tertiary: Chemicals are used to remove excess phosphates, ammonia, nitrogen, clarify water with activated carbon, treat with chlorine to kill residual microorganisms
What are the 3 steps for proper treatment or water and sewage ensures safe drinking water?
Water purification can be boiled down into
- Sedimentaiton
- Filtration
- Chlorination
What is added to domestic human waste in septic tanks?
Dried bacillus subtitles to accelerate digestion ins epic tanks/cesspool
Where does livestock waste get stored?
In oxidation lagoons where natural digestion occurs
