Water Technology

Question 1

hard water

Answer 1

which doesnt produce a ready and permanent lather with soap solution

Question 2

what causes hardness of water

Answer 2

presence of dissolved salts of Ca, Mg and some other heavy metals

Question 3

what causes temporary hardness

Answer 3

presence of bicarbonates of Ca, Mg and other heavy metals, carbonates of Fe and bicarbonate of sodium

Question 4

how can hardness of water be removed

Answer 4

simple boiling

Question 5

what causes permanent hardness

Answer 5

presence of chloride and sulphate of Ca, Mg, Fe and other heavy metals

Question 6

parts per million

Answer 6

number of parts of CaCO3 equivalent hardness present in 10^6 parts of water

Question 7

milligram per litre

Answer 7

number of milligrams of CaCO3 equivalent hardness present in 1 L of water

Question 8

clarkes degree

Answer 8

number of parts of CaCO3 equivalent hardness present in 7000 parts of water

Question 9

frenche degree

Answer 9

number of parts of CaCO3 equivalent hardness present in 10^5 parts of water

Question 10

why is conc of dissolved impurities present in water usually expressed in terms of equivalents of calcium carbonate salt

Answer 10

1) molec weight is 100 and equivalent weight 50, convenient for calc
2) CaCO3 is most insoluble substance formed during water treatment

Question 11

troubles in boilers

Answer 11

1) scale and sludge formation
2) caustic embrittlement
3) boiler corrosion
4) priming and foaming

Question 12

external treatment method

Answer 12

removing hardness producing salts from water outside the industrial equipment

Question 13

polymer ion exchange process

Answer 13

external treatment method in which temporary and permanent hardness can be removed

Question 14

2 types of ion exchange resins

Answer 14

cation

anion

Question 15

differentiate between cation exchange resin and anion exchange resin

Answer 15

cation:
contains acidic functional grps
RH2
eg. sulphonated coal
Dowex-50
anion:
contains basic func grps
R(OH)2
eg. phenol formaldehyde
Dowex-3

Question 16

mixed bed deioniser

Answer 16

consist of single cylinder containing an intimate mixture of strongly acidic cation exchanger and strongly basic anion exchanger

Question 17

advantages of mixed bed deionizer

Answer 17

1) water containing high acidity and alkalinity can be purified
2) water with low residual hardness is obtained
3) the softened water is completely free from all the salts

Question 18

desalination

Answer 18

process of removing extra common salt from water

Question 19

principle of reverse osmosis

Answer 19

when a P higher than osmotic P is applied externally, osmosis takes place in opposite direction

Question 20

osmosis

Answer 20

passage of solvent molecules from a lower conc region to higher conc region through a semi permeable membrane

Question 21

ultra filtratiion membrane

Answer 21

used for RO process

Question 22

advantages of ultrafiltration membrane

Answer 22

1) low capital cost
2) removes colloidal silica
3) removes ionic, non ionic, colloidal and high molec weight organic impurities

Question 23

applns of ultrafiltration membrane

Answer 23

prodn of purified drinking water

purifying water for mixing beverages, ice making, cooking

Question 24

potable water

Answer 24

water safe to drink

Question 25

sedimentation with coagulation

Answer 25

removing fine suspended and colloidal impurities

Question 26

chemical methods of disinfection

Answer 26

``` addn of potassium permanganate addn of bleaching powder using chloramine addition of O3 addn of liq Cr ```

Question 27

phy methods of disinfection

Answer 27

simple boiling passing UV passing sun light

Question 28

advantages of chlorination

Answer 28

``` effective and economical requires less space for storage stable introduces no salt impurities most ideal ```

Question 29

disadvantages of chlorination

Answer 29

excess -> unpleasant taste and odour - > irritation - > precipitates other ingredients present

Question 30

break point of chlorination

Answer 30

addn of Cl to the point tht it kills all and completely destroys impurities

Question 31

advantages of disinfectation by UV

Answer 31

``` environment friendly highly effective no toxic byprods removes other org and toxic contaminants very less contact time improves taste ```

Question 32

advantages of O3 disinfection

Answer 32

O3 sterilizes, bleaches, decolourises and deodurises effective and rapid chemical free no regrowth

Question 33

disadvantages of O3 disinfection

Answer 33

expensive | special mixing techniques

Question 34

saturation level of O2

Answer 34

max conc of dissolved O2 that would be present in water at a specific temp in the abs of other factors

Question 35

winkler method

Answer 35

to measure dissolved O2 level in fresh water systems

Question 36

factors affecting DO

Answer 36

``` climate altitude dissolved or suspended solids amt of nutrients org wastes groundwater flow type and no. of organisms in water body ```

Question 37

Biochem Oxygen Demand

Answer 37

amt of O2 req for biochem oxdn of org matters present in a sewage under aerobic condn at 20oC for 5 days

Question 38

chemical oxygen demand

Answer 38

o2 req for complete oxdn of org matter present in sewage in the presence of strong chem oxidising agents