lecture 5 to 8a

Question 1

what are the different ways the stabilization (degradation) of wastewater is accomplished?

Answer 1

• conversion of colloidal and dissolved carbonaceous organic matter into gases and biosolids (cell mass)
• S.G. of biosolids > S.G. water, therefore biosolids can be removed via gravity settling or filtration
• some specific types of microorganisms can also remove nutrients (N, P,) from wastewater

Question 2

what is required for microorganisms grow?

Answer 2

• carbon and energy
• nutrients (N,P)
• Trace elements (S, Mg, K)

Question 3

classification based on O2 presence: Obligate aerobes

Answer 3

must have molecular O2 present

Question 4

classification based on O2 presence: Obligate anaerobes

Answer 4

presence of O2 is toxic

Question 5

classification based on O2 presence: Facultative aerobes

Answer 5

can grow in absence/presence of O2

Question 6

classification based on O2 presence: Microaerophillic

Answer 6

obligate aerobes, but only in low O2 concentrations

Question 7

what are some environmental factors to consider for functions of micro-organisms

Answer 7

• pH
• chemical composition of “food” (organic matter)
• O2 concentration
• temp.
• light availability

Question 8

true or false: identification and enumeration of all microorganisms present in water samples would be TEDIOUS, LONG AND VERY EXPENSIVE

Answer 8

true

Question 9

what are the 3 types of indicator organisms (commonly used)

Answer 9

1. total coliform (from soil, feces, other origins)
2. Fecal coliform (from guts of humans, warm blooded animals)
3. E. Coli> (one of the coliform bacteria group, more representative of fecal source than other coliform genre)

Question 10

what is the criteria for the choice of indicator organisms?

Answer 10

1. should always present when pathogenic organisms of concern is present, and absent in clean uncontaminated water
2. should be present in fecal material in large quantity
3. should respond to natural environmental conditions and to treatment processes in a manner similar to pathogens of interest
4. easy to isolate identify and enumerate
5. ratio of indicator to pathogen high
6. indicator and pathogen should come from the same source

Question 11

what are the different methods of counting the number of bacteria cells per milliliter, gram or cubic meter of a sample?

Answer 11

1. membrane filtration technique
2. presence and absence test
3. fermentation tube technique

Question 12

what are the water quality standards based on?

Answer 12

a) established or ongoing practice
b) technical attainability
c) economic attainability
d) ability to measure parameters reliably
e) evidence derived from accidental human exposure
f) educated guess based on available info and judgement
g) application of mathematical models (simulation of health risks)
h) legal enforceability

Question 13

what are some methods for groundwater treatment?

Answer 13

aeration
lime soda ash addition
flocculation
sedimentation
recarbonation
filtration, disinfection and sludge processing

Question 14

what is an intake facility?

Answer 14

facilities to divert and transport water from a supply source to a pumping station, collector well or directly to water treatment facility

Question 15

what are some types of racks and screens?

Answer 15

intake bar rack (coarse screens)
(fine screens) travelling belt screen

Question 16

what are some specifications for an intake bar rack?

Answer 16

• located at water intakes from rivers and lakes to prevent entry of large materials
• the clear spacing between bars composing the rack varies from 1 to 3 in
• a trolley and hoist is often installed (manually or automated operation for cleaning

Question 17

what are some specifications for fine screen (travelling belt screen)?

Answer 17

• consists of wire mesh with opening sizes from 0.25 to 0.35 in.
• often used following bar racks to prevent small fish from being drawn into the intake
• can be hydraulically cleaned (back flush)
• if fish present - fish lift buckets and low-pressure wash

Question 18

what are some goals regarding the design and operation of screens?

Answer 18

minimize head loss
average velocity
continuous cleaning

Question 19

how are screens disposed?

Answer 19

usually disposed of in a landfill

Question 20

what is an infiltration gallery?

Answer 20

natural pretreatment process
- collect water that naturally infiltrates through the soil allowing it to undergo natural filtration as it percolates through the ground
- removed suspended solids and to some extent, pathogens, making the water cleaner and easier to treat downstream