11.1 Granular Filtration

Question 1

why must turbidity be reduced?

Answer 1

reduce interference with subsequent disinfection processes

Question 2

separation of suspended or colloidal impurities by passage through a porous medium

Answer 2

filtration

Question 3

four typical filtration mediums

Answer 3

sand, coal, activated carbon, garnet

Question 4

what increases as material accumulates in the interstices of the granular medium

Answer 4

headloss

Question 5

what happens when the headloss or effluent turbidity reaches a predetermined limit?

Answer 5

filter is backwashed

Question 6

what governs the cleaning cycle?

Answer 6

headloss or effluent turbidity

Question 7

what varies during the filtration cycle (filter run)?

Answer 7

efficiency of particle removal

Question 8

stage that occurs initially as the filter is put back into service

Answer 8

ripening (maturation)

Question 9

trend of efficiency throughout filtration cycle

Answer 9

increases

Question 10

dual media

Answer 10

coal plus sand

Question 11

mixed media

Answer 11

coal, sand, garnet

Question 12

three pretreatment level classifications

Answer 12

conventional, direct filtration, in-line/contact filtration

Question 13

three hydraulic rate classifications

Answer 13

slow sand, rapid sand, high-rate