Biological Characteristics of Water

Question 1

How is stabilization (degradation) of organics in wastewater achieved?

Answer 1

• Conversion of colloidal and dissolved carbonaceous organic matter into gases and biosolids
• Specific gravity of biosolids is greater than water so they can be removed through settling
• Microorganisms can also remove nutrients from wastewater

Question 2

What do microorganisms need to grow?

Answer 2

• Carbon and energy
• Nutrients (N, P)
• Trace elements (S, Mg, K)

Question 3

Micro organisms can be classified based on their energy and carbon sources. Name these four classifications and where their energy and carbon come from

Answer 3

1) Chemo-autotrophs (chemical, inorganic)
2) Chemo-heterotrophs (chemical, organic)
3) Photo-autotrophs (light, inorganic)
4) Photo-heterotrophs (light, organic)

Question 4

What are the four classifications of microorganisms based on oxygen presence?

Answer 4

1) Obligate Aerobes (molecular oxygen must be present)
2) Obligate Anaerobes (Molecular oxygen presence is toxic)
3) Facultative Anaerobes (can grow in the presence or absence of molecular oxygen)
4) Microaerophilic (obligate aerobes that function best at low oxygen levels)

Question 5

What environmental factors affect the growth of microorganisms in water?

Answer 5

• pH
• food (organics)
• O2
• temperature
• availability of light

Question 6

What are the five main microorganisms in water and wastewater?

Answer 6

• Bacteria
• Helminths
• Viruses
• Fungi and Algae
• Protozoa

Question 7

Giardia and Cryptosporidium (protozoa) are resistant to commonly used disinfectants like chlorine, true or false?

Answer 7

True, chlorine will not get rid of protozoa on its own (Cryptosporidium is more resistant than Giardia)

Question 8

What does effective reduction of protozoa in drinking water require?

Answer 8

Combination of physical removal (filtration) and disinfection barriers (chlorine, UV, ozone)

Question 9

What are the three commonly used indicator organisms?

Answer 9

1) Total coliform
2) Fecal coliform
3) E. Coli

Question 10

E. Coli is found in Fecal Coliform which is found in Total Coliform, true or false?

Answer 10

True

Question 11

What concentration of E. Coli. (CFU/100mL) in source water would be of reasonable quality?

Answer 11

0 to 10 CFU/100mL

Question 12

What concentration of E. Coli. (CFU/100mL) in drinking water would be acceptable?

Answer 12

0 CFU/100mL

Question 13

Water treatment has a multi-barrier approach, true or false?

Answer 13

True