Purification

Question 1

what characteristics affect self purification processes of water

Answer 1

Hydraulic : vol,rate,turbulence of flow
physical : bottom and bank material;variations in sunlight and temp
chem nature of water

Question 2

processes

Answer 2

dilution, sedimentation and resuspension,filtration, gas and heat transfer

Question 3

Conc after mixing

Answer 3

CsQs+CwQw=CmQm; C is conc, Q is vol flow rate, s,w and m are stream, waste and mixture

Question 4

how do solids affect water (suspension)

Answer 4

increase turbidity
reduced light penetration affects vision of animals
interferes w their feeding
abrasive to resp structures gills

Question 5

drawbacks of sedimentation

Answer 5

1. anaerobic conditions develop in sediment deposits and org materials decompose and release soluble compounds into the water
   2.affect the streambed by filling up the pore space
   3.create unsuitable conditions for reprod of aquatic animals
   4.development of banks of silt and mud along bottom of streams alter its course or navigation activities
2. reduce reservoir storage capacities and silt in harbours
   6.inc flooding due to channel fill-in

Question 6

resuspension of solids

Answer 6

resuspend solids, during flooding or heavy runoff
increase turbidity

Question 7

nn

Answer 7

jj

Question 8

filtration how

Answer 8

small bits are filtered by pebbles or rocks along streambed
water percolates from surface to groundwater aquifers

Question 9

gas transfer why

Answer 9

oxygen lost is replenished; gases evolved in water are transfered to atm

Question 10

gas transfer affceted by

Answer 10

solubility and transfer rate

Question 11

solubility of gas in eqm by Hnerys law

Answer 11

x=P/H

Question 12

What is x

Answer 12

eqm mole fraction of dissolved gas at 1 atm; x= ng/(ng+nl)

Question 13

H what

Answer 13

coefficient of absorption

Question 14

P

Answer 14

press of gas above liq

Question 15

other factors affecting solubility

Answer 15

temp and conc

Question 16

how temp

Answer 16

solubility inc as temp dec

Question 17

how conc

Answer 17

solu decreases as dissolved material in liq inc

Question 18

what does H vary with

Answer 18

temp

Question 19

when does desorpn occur

Answer 19

when C greater than Cs

Question 20

what does Ka depend on

Answer 20

1. temp of system
2. interfacial area available for gas transfer
   3.resistance to movmt from one phase to other

Question 21

what is the rate limiting step

Answer 21

step which shows most resistance to movmt of gas molec

Question 22

what is the rate limiting step

Answer 22

step which shows most resistance to movmt of gas molec

Question 23

how does inc in water temp affect

Answer 23

affects ionic strength,conductivity, dissoc constants, solubility and corrosion potential