L5 - Biological Characteristics of Water Flashcards
Why is microbiology or biological characteristics of water important?
Public health, physical and chemical water quality, and treatment plant operation.
Why use a variety of microorganisms to treat water?
- conversion of colloidal and dissolved carbonaceous organic matter into gases and biosolids
- S.G. biosolids > water so biosolids can be removed with settling or filtration
- Can remove nutrients from wastewater
What nutrients are required for microorganisms
Carbon and energy
Nutrients (N , P)
Trace Elements (S, Mg, K)
Obligate aerobes
Must have molecular O2 present
Obligate anaerobes
Molecular O2 is toxic
Facultative Anaerobes
Can grow with or without O2
Microaerophillic
Function best at low O2
What environmental factors affect microorganisms
-Ph
-Food (Organics)
-O2
-Temperature
Main Microorganisms in water and wastewater
-Bacteria
-Rotifers (Worms)
-Viruses
-Algae
-Protozoa (Resistant to Chlorine)
What are three common indicator organisms?
- total coliform
- Fecal coliform
- E. Coli
Criteria of choice of indicator organisms
- Should always present when pathogenic organisms of concern is present, and absent in clean uncontaminated water
- Should be present in fecal material in large quantity
- Should respond to natural environmental conditions and to treatment processes in a manner similar to pathogens of interest
- Easy to isolate, identify and enumerate
- Ratio of indicator to pathogen high
- Indicator and pathogen should come from the same source
What are the different methods of counting bacteria cells per milliliter or gram of sample
- Membrane Filtration technique (Counting colonies)
- Presence and Absence Test (Alerting Presence but not amount)
- Fermentation Tube Technique (Test based on gas production
