wastewater treatment plant lecture WWT1.pdf

wastewater treatment plant lecture

1. Wastewater Treatment
WW1
By
Dr. Amr Abdel Kader
Specialized Scientific Programs
Civil & Environmental Engineering
Dr Amr Abdelkader San 419 1

2. BASICS
•WHAT IS WASTEWATER?
•WHY IT IS ENVIRONM. UNFRIENDLY?
•WASTEWATER COMPOSITION?
•WHAT ARE WASTEWATER SOURCES?
•WHY WE NEED TO TREAT IT?
•WASTWATER CHARACHTERISTICS?
•WHAT ARE THE TWO BASIC EQUATIONS OF
WASTEWATER TREATMENTS?

3. COMPOSITION OF WW
•99.9 WATER + 0.1 SOLIDS
•TS = 100 THEN;
•TSS = 30
•SETLEABLES = 15 (ORGANIC = 10 AND
INORGANIC = 5)
•NON SETLEABLES = 15 (ORGANIC = 10 AND
INORGANIC = 5)
•TDS = 70
•ORGANIC = 30
•INORGANIC = 40
•TOTAL ORGANIC = 50
•TOTAL INORGANIC = 50

4. REMEMBER!
•ORGANICS + O2
STABLE ORG. MATTER + CO2 + H2O
•ORGANICS (WITHOUT O2)
STABLE ORG. MATTER + CO2 + H2O

5. TERMINOLOGIES TO BE
REMEMBERED!
•BOD 5, 20
•COD
•TS = TSS + TDS = TVS + TFS
•TSS = TVSS + TFSS
•TDS = TVDS + TFDS
•TVS = TVSS + TVDS
•TFS = TFSS + TFDS
•MLSS, MLVSS

6. WASTEWATER TREATMENT
ENVIRONMENT
•TEMP., PH, NO TOXIC…
•WHAT BACTERIA CAN EAT.
•IS FOOD CONCENTRATION MATTERS!!!!! ….FOOD TO
MICROORGANISMS RATIO.
•IS TIME IMPORTATNT? WHAT TIME? HRT OR SLUDGE
AGE..?
•NUTRIENTS MATTERS? ORGANIC:N:P = 100 : 5 : 1
•AERATE AND MIX WITH NO SETTLING,….. SETTLE
WITH NO AERATE AND MIX!!!! DON’T MIX
PROCESSES!!!
Dr Amr Abdelkader San 419 6

7. WASTEWATER TREATMENT
ENVIRONMENT
•SOLIDS SEPARATE FIRST BY EASY MEANS..
•GIVE AEROBIC BACTERIA AIR AND
PREVENT AIR FROM ANAEROBIC BACTERIA
•HOW U GIVE AIR TO AEROBIC ANAEROBES
(CASCADES, MECHANICAL (SA,
DIFFUSERS), NATURALLY).
Dr Amr Abdelkader San 419 7

8. WASTEWATER TREATMENTS
•PRE-TREATMENT (SCREEN, GRIT REMOVAL)
•PRIMARY TREATMENT (PLAIN SETTLING OR
DISSOLVED AIR FLOTATION)
•SECONDARY TREATMENT
•TERTIARY TREATMENT
Dr Amr Abdelkader San 419 8

9. WASTEWATER TREATMENTS
•PRETREATMENT
•SCREEN; MECHANICAL AND MANUAL
•GRIT REMOVAL
•OIL AND GREASE
•PRE-AERATION
•EQUALIZATION
•HEAVY METALS SEPARATION
Dr Amr Abdelkader San 419 9

10. WASTEWATER TREATMENTS
PRIMARY
•PHYSICAL; FLOTATION, SEDIMENTATION
•CHEMICAL; NEUTRALIZATION, COAGULATION
Dr Amr Abdelkader San 419 10

11. WASTEWATER TREATMENTS
•SECONDARY
•DISSOLVED ORGANIC REMOVAL
•SUSPENDED GROWTH
•ACTIVATED SLUDGE, OXIDATION DITCH,
AERATED LAGOON, PONDS, UASB,
ANAEROBIC POND
•ATTACHED GROWTH
•TRICKLING FILTER, RBC, FLUDIZED BED,
UAFFRAERATED LAGOON
•SUSPENDED SOLIDS REMOVAL
•SETTLING; PLAIN OR CHEMICALLY
Dr Amr Abdelkader San 419 11

12. WASTEWATER TREATMENTS
•TERTIARY
•FILTRATION
•COAGULATION AND SEDIMENTATION
•CARBON ADSORPTION
•MEMBRANE
•MICROSTRAINER
•POLISHING PONDS
•WEEDS
Dr Amr Abdelkader San 419 12

13. WASTE WATER TREATMENT
•Primary Treatment (Physical Treatment)
Physicaltreatmentdependsonlyonthephysicalcharacteristicsofimpurities
thatpresentinwastewatertobetreated.So,itsefficiencyissmall.
•Secondary Treatment (Biological Treatment)
Secondarytreatmentdependsonthebiologicalcharacteristicsof
microorganismsthatpresentinwastewatertobetreatedsuchasbacteriathat
helpsintheremovaloforganicmatters.
•Tertiary Treatment (Polishing)
Incaseofrequiredaneffluentwithverygoodcharacteristics,tertiarytreatmenthas
beendone.Itcanremovesalts,odor,tasteandtherestoforganicmatterusingfor
example(ActivatedCarbonFilter,DynasandFilter.…etc).
Dr Amr Abdelkader San 419 13

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15. Dr Amr Abdelkader San 419 15

16. Dr Amr Abdelkader San 419 16

17. PURPOSE OF
PRIMARY TREATMENT
Removal of
•Large and big floating particles.
•(40 to 60 %) of SS and (25 to 35 %) of BOD.
•Sand, gravel, silt…..etc.
•Oil and grease.
Dr Amr Abdelkader San 419 17

18. Purpose of
Preliminary Treatment Units
Deceleration Chamber
Decreasing velocity of flow before the screen to prevent the
escaping of particles from the screening opens.
Approach channel
Transmission of waste water from deceleration chamber to screen
at aerated condition and with suitable velocity that helps in
avoid anaerobic reaction between units.
Dr Amr Abdelkader San 419 18

19. Screen
head loss
By pass
d
10 cm
d'
V1
V2
L
Coarse Screen
Elevation
Plan
B
From approch channel
To GRC Dr Amr Abdelkader San 419 19

20. Grit Removal Chamber
Elevation
Plan
Scrapper chain
Screew pump
Motor
Proportional weir
L
B
Grit
From screen Efflent
Grit
d
Hopper Dr Amr Abdelkader San 419 20

21. Screen
It's used to remove big and strange impurities from waste
water, such as (paper –wood –plastics -…..), to protect the
down stream equipment against damage.
Skimming Tank
Removal of oil, grease and most of float matters.
Grit removal chamber (GRC)
Removal of particles has size more than 0.2 mm, such as (sand,
gravel, grit …..etc), to:
Protect down stream mechanical equipment.
Reduce conduit clogging.
Prevent interface with other treatment.
Improve sludge quality.
Dr Amr Abdelkader San 419 21

22. Screw Pump
Dr Amr Abdelkader San 419 22

23. Preliminary Treatment
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24. DECCELERATION CHAMBER AND SCREEN
Dr Amr Abdelkader San 419 24

25. Force mains and deceleration chamber
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26. Screens
Dr Amr Abdelkader San 419 26

27. Mechanical Screens
Dr Amr Abdelkader San 419 27

28. Screening
Dr Amr Abdelkader San 419 28

29. Screening Disposal
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30. MECHANICAL SCREEN
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31. GRIT REMOVAL CHAMBERDr Amr Abdelkader San 419 31

32. •Removal of 40 to 60 % of SS
•Removal of 25 to 35 % of BOD
•Removal of Oil and Grease
Purpose of
Primary Sedimentation Tank
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33. PRIMARY SEDIMENTATION TANK (Rectangular)Dr Amr Abdelkader San 419 33

34. PRIMARY SEDIMENTATION TANK (Circular)Dr Amr Abdelkader San 419 34

35. Design Criteria of Preliminary Treatment Units
1.Deceleration chamber
Q
av=Pop*(av.SF)
Peakfactor(PF)=(18+(Pop)
0.5
)/(4+(Pop)
0.5
),(Popinthousand).
Minimumfactor(MF)=0.2*(Pop)
1/6
,(Popinthousand).
SF=sewageflow=0.8to0.9fromaveragewaterconsumption.
Q
d=Q
max=PF*Q
av
RT=1to3min.
n≥1(take1atfirst)
Vol=nLBd
SA=nLB
XA=nBd
L=(2to4)*B
d=1–2m
Velocity=0.6to1.5m/s
Wastewater Treatment Calculation
Dr Amr Abdelkader San 419 35

36. 2. Approach channel
Openchannelflow(manning)
Q
av=Pop*(av.SF)
Q
d=Q
max=PF*Q
av
n≥1(take1atfirst)
XA=nBd
V=0.6to1.5m/s
AssumeV
max=1.5m/s
B=2dmax(bestsection)
Get(B,d
max)atQ
max
Assume(1/n)=60
AssumeV
min=0.6m/s
Q
min=V
min*A
min=0.6*Bd
min
Thenget(d
min)
FrommanninggetS
min
V
min=(1/n)R
(2/3)S
min(1/2)
R=Area/wettedperimeter=Bd
min/(B+2d
min)
Assume(1/n)=60
Afterthatyoucangetd
maxatV
maxfrommanningalso.Fixtheslope.
Dr Amr Abdelkader San 419 36

37. Dr Amr Abdelkader San 419 37

38. Typesofscreen
Coarsescreen.Spacebetweenbars(5–10cm)
Mediumscreen.Spacebetweenbars(2–5cm)
Finescreen.widthofopening=(0.08–0.24cm),circularplate),
lengthofopening=(0.64–5.1cm)
Reasonsforusingfinescreen
WhenthePSTisoverloaded.
Withcertaintypesofindustrialwastewater.
WhenthePSTisn'tused.
Whenthereisnosecondarytreatment.
Disposalofthescreening(screenedmaterial)
Sanitarylandfills.
Incineration.
Grindingandreturntotheheadworksoftheplant.
3. Screen
Dr Amr Abdelkader San 419 38

39. Design of coarse screen
The velocity before the bar screen (V
1) ≥ 0.6 m/s
The velocity between the bar screen (V
2) ≤ 1.5 m/sec
Where V
1= Q
max/ (nBd')
Where V
2= Q
max/ (nNSd')
h loss through the screen = 1.4 (V
2
2
–V
1
2
)/2g
h loss ≤ 10 cm (at the beginning of working)
h loss ≤ 30 cm (before cleaning)
Q
d= Q
max= PF * Q
av
Q
av= Pop * (av. SF)
n ≥ 2 (take 2 at first) + by pass
A
netin inclined plane = 2 to 3 (approach channel area)
A
netin inclined plane = n (N S L) m
2
Where,
N = no. of spacing in one screen = no of bars –1
S = spacing between bars = according to screen type (coarse –medium)
L = d' / sinθ
d' = d (of approach channel + 5 to 10cm)
θ = 30 –60o (manual screen)
Screen bar diameter (Ø) = 1.3 –1.6 –1.9 cm
The screen width = B = (N + 1)*Ø + N * S
Dr Amr Abdelkader San 419 39

40. 4.GritRemovalChamber
Methodsusedtocontrolvelocityofthechamber
•Useparabolacrosssectionarea.
•Userectangularcrosssectionwithproportionalweirattheendofthe
chamber.
Designdataofrectangulartype
Q
d=Q
max.
Horizontalvelocity=0.25to0.35m/s
RT=45to90sec(take60)
SLR=1000to2500m
3
/m
2
/d(take1200)
n≥2
L=15to20mB≤d
Dr Amr Abdelkader San 419 40

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42. Design Criteria of Primary Sedimentation Tank
Purpose
Removalof40to60%ofSS
Removalof25to35%ofBOD
Designdata
Retentiontime=T=1.5to2.5hr(incaseofflowedwithsecondary
treatment),=2to4hr(incaseofnosecondarytreatment
appearance)
SLR=30to45m3/m2/d
HLOW=150to600m3/m2/d
d=3to5m
B=2to3d
L=4to5B
L≤50m
Ø≤35m
Dr Amr Abdelkader San 419 42

43. Factors affecting efficiency of
sedimentation process
1.Shapeandsizeofsolids.
2.Specificgravityofsuspendedsolids.
3.Temperature.
4.Velocityofflow.
5.Retentiontime.
6.Efficiencyofpervioustreatment.
7.Sludgeremovalmethod.
8.Scumremovalmethod.
9.Surfaceloadingrate.
10.Viscosityofsewage.
11.Specificgravityofsewage.
12.Inletandoutletarrangement.
Dr Amr Abdelkader San 419 43

44. Example
Designthefollowingtreatmentunitsforasewagetreatment
plant:
•GRC(conventionalwithproportionalweir).
•PST(rectangular)
Giventhefollowingdata:
•Averagesewageflowis17,280m
3
/d
•SLRofGRC=1200m
3
/m
2
/d
•SLRofPST=30m
3
/m
2
/d
Dr Amr Abdelkader San 419 44

45. Solution
AssumePF=1.5So,Qmax=1.5*17,280=25,920m
3
/d
DesignofGRC
RT=45–90sec=60sec=Vol./Q
SLR=1000–2500=1200m
3
/m
2
/d=50m
3
/m
2
/hr=Q/SA
V=0.25–0.35=0.3m/s=1080m/hr=Q/XA
RT*V=L=18m
nBL=36B=SA=25,920/1200=21.6m
B=0.6m
Vol.=18m
3
d=0.85m
Dr Amr Abdelkader San 419 45

46. DesignofPST
Q
d=1080m
3
/hr
AssumeR.T=
3
hrs
Volume=3*1080=3240m
3
=nLBd
AssumeSLR=30m3/m2/d=1.25m
3
/m
2
/hr
SA=1080/1.25=864m2=nLB
d=3240/864=3.75m
Assume B = 2d = 7.5 m
Assume L = 4B = 30 m
n = 4 tanks
The important checks
RT = 3375 / 1080 = 3.125 hr
SLR = (1080 / 900) *24 = 28.8 m
3
/m
2
/d (safe but waste)
V
f= (1080/ 112.5*60) = 0.16 m/min
HLOW = (1080/30) * 24 = 864 m
3
/m/d
Take L
w= 55 m, HLOW = 471 m
3
/m/d (ok)
Dr Amr Abdelkader San 419 46

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