wastewater treatment plant lectureWWT2.pdf

wastewater treatment plant lecture

1. Wastewater Treatment
WW2
By
Dr. Amr Abdel Kader
Dr Amr Abdelkader San 419 48
Specialized Scientific Programs
Civil & Environmental Engineering

2. The effluent of primary treatment still
contains relatively large quantities of
organic matter in suspension or in solution
BIOLOGICAL TREATMENT
TARGET
Transformation of organic matter into
stable non offensive compounds
PROBLEM
Dr Amr Abdelkader San 419 49

3. TYPES OF BIOLOGICAL TREATMENT
50

4. AEROBIC PROCESS
ATTACHED GROWTH
TRICKLING FILTERS
Trickling-filter systems are commonly used for
secondary treatment of municipal wastewater
Primary effluent is sprayed on bed of crushed rock or
gravel coated with biological films
Removal of the organic matter is the result of an
adsorption process which occurs at the surface of
biological slimes covering the filter media
Dr Amr Abdelkader San 419 51

5. After 2 weeks
Sewage drops + Oxygen
Media
Thin layer of OM + Bac. Inner layer (Partialy Oxidized)
Outer layer (Full Oxidized)
Sewage drops
Outer Layer Sloughing
Anerobic Reaction + Gases
Gases
Aerobic Reaction
Aerobic Reaction
Anaerobic Reaction
For inner layer
After Totaly Dec.
of inner layer
Gases
Sewage drops
Outer and Inner Layers Sloughing
Figure (1/2). Mechansim of BOD Removal in Attached Growth Biological Treatment Dr Amr Abdelkader San 419 52

6. TRICKLING FILTERS TYPES
High Rate
Trickling Filter
Standard Rate
Trickling Filter
Sewage flow is
intermittently applied
but uniformly
distributed in the form
of a spray over the filter
media
Sewage flow is continuously
applied and uniformly
distributed in the form of a
spray over the filter media
Part of effluent from the final
settling tank is returned to the
influent of the filter
(Circulation)
Dr Amr Abdelkader San 419 53

7. Flow Diagram in Standard Rate Trickling Filter WWTP
54

8. Flow Diagram in High Rate Trickling Filter WWTP
55

9. High Rate Trickling Filter
Dr Amr Abdelkader San 419
56

10. Dr Amr Abdelkader San 419 57

11. Trickling Filter
58

12. Trickling Filter
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13. Comparison of Low Rate and High Rate Trickling Filter
Dr Amr Abdelkader San 419 60

14. Standard rate trickling filter
Advantages:
1-highefficiency:BOD&suspendedsolidremoval>95%
2-lowoperation&maintenancecost
3-Noskilllaborisrequired
Disadvantages:
1-Rateoffiltrationislow1-4m³/m²/day.
2-Largeareaisrequired.
3-Constructioncostishigh.
4-Breedingplaceforflies.
Dr Amr Abdelkader San 419 61

15. High rate trickling filter
Advantagesofrecirculation:
1-Returnoxygenwithwastewater.
2-Returnactivebacteriatoincreasereactionrate
whichdecreasetherequiredareafortheincreaseof
theallowableload.
3-DecreasetheconcentrationofBODonfilter.
4-Achievetheplantworkingdaybynight.
5-Preventthegrowthofflyaroundthefilter.
6-Makethegravelwetatanytime.
Dr Amr Abdelkader San 419 62

16. Disadvantages:
1-Cost of pumps & equipment.
2-Decrease the overall efficiency of the plant.
3-Continuity of toxic components if it exists.
Dr Amr Abdelkader San 419 63

17. Design of Trickling Filters
BOD
1(Raw water)
BOD
2(Primary treated)
BOD
3(Secondary treated)
% Primary treatment efficiency (PTE) = [(BOD
1-BOD
2)/ BOD
1] * 100
% Combined efficiency (CE) = [(BOD
2–BOD
3)/ BOD
2] * 100
% Overall efficiency (OE) = [(BOD
1–BOD
3)/ BOD
1] * 100
Dr Amr Abdelkader San 419 64

18. Where:
•% CE = [1/(1+0.0085(2.72L
o/F)
0.5
)]*100
•F = Recirculation Factor = [(1+R)/(1+0.1R)
2]
•Allowable Hydraulic Load (h
o) = (Q
d+ RQ
d)/(SA)
•Allowable Organic Load (L
o)
•Total Organic Load (TOL) = [Q
d* B
2+ RQ
d* B
3] gm BOD/d
•Volume = (TOL/L
o) m
3
•Surface Area = (Circular in shape), Ø ≤ 35 m
•For all units n ≥ 2 unitsDr Amr Abdelkader San 419 65

19. Allowable BOD Loading on High Rate and Low
Rate Filter in Kg/1000 m
3
of Filter Media per Day
Dr Amr Abdelkader San 419 66

20. Recirculation Ratios in High Rate Filters
Dr Amr Abdelkader San 419 67

21. Egyptian code
Dr Amr Abdelkader San 419 68

22. 69

23. 70

24. Dr Amr Abdelkader San 419 71

25. 72

26. Example 1
•Asewagetreatmentplantofdailydischarge18000
m
3
.Findthenumbersanddimensionsofstandard
rateandhighratetricklingfiltersif:
-RowsewageBOD5=250mg/l
-EffluentBOD5=40mg/l
-BOD5removalefficiencyofprimary
sedimentation=30%
-Recirculationratio(R)(athighrate)is1.5the
designflow.
Dr Amr Abdelkader San 419 73

27. Solution
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28. Dr Amr Abdelkader San 419 75

29. High rate TF
76
P.S.T
F.S.T
H.R.T.F
BOD
0
250 mg/l
BOD
1
BOD
2
40 mg/l
BOD
2
Q
R
=RxQ
d89.1
)5.11.01(
5.11
)1.01(
1
7.2
0085.01
100
%1.77100
175
40175
100
22
1
21
=
+
+
=
+
+
=
+
=
=
−
=

−
=
R
R
F
F
L
efficiencyCombined
BOD
BODBOD
efficiencyCombined

30. Dr Amr Abdelkader San 419 77

31. Dr Amr Abdelkader San 419 78

32. ROTATING BIOLOGICAL
CONTACTORS (RBC)
Influent
Effluent
Primary
Treatment
Secondary
Clarifier
Contactors
Solids Removal
79

33. RBC Secondary Treatment
Plastic Media
1.6 rpm
40 %
Submerged
Microorganisms “Treat” the Wastewater by Using Organics
Provides Large Surface Area
Rotating
Dr Amr Abdelkader San 419
80

34. Biomass
Media
(disc)
Organics
Oxygen
Liquid Film
Oxygen
Dr Amr Abdelkader San 419 81

35. Organics
Liquid FilmLiquid Film
Media
BIOMASS
Random
Continuous
Sloughing
82

36. Pretreatment
Primary
Treatment
Rotating
Biological
Contactors
Secondary
Clarifiers
Solids Handling
INFLUENT
Disinfection
EFFLUENT
RBC Flow Scheme
Dr Amr Abdelkader San 419 83

37. ADVANTAGES OF RBC PROCESS
Simple Operation
Low Energy Requirements
Nitrification
Wide Flow Range
Handles Shock Loads
Few Nuisances
Low Head Loss
Large Biological Population
Dr Amr Abdelkader San 419 84

38. DISADVANTAGES
OF RBC PROCESS
Limited Controls
Enclosures
Limited Experience and
Training
Dr Amr Abdelkader San 419 85

39. RBC COMPONENTS
TANK
CONTACTOR
CLARIFIER
Dr Amr Abdelkader San 419 86

40. RBC COMPONENTS
CONTACTOR
Shaft
Individual Disc
Discs
Dr Amr Abdelkader San 419 87

41. Media“High Density” Polyethylene
Carbon
Black
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42. Media –Irregular Surface
Maintain Spacing
Increases Rigidity
Increases Surface Area
Increases Contact Time
Dr Amr Abdelkader San 419 89

43. Media –Irregular Surface
“Corrugated”
Dr Amr Abdelkader San 419 90

44. Media
BIOMASS
1 Inch
Dr Amr Abdelkader San 419 91

45. 10 to 12 Ft
Diameter
~ 25 Ft
Long
Dr Amr Abdelkader San 419 92

46. “Train”
RBC Systems Usually More Than One
Contactor with Flow Progressing in Series in a
“Train” Dr Amr Abdelkader San 419 93

47. Influent
Effluent
Baffles
Enclosure
Larger Systems –Contactors are Set in Series in
Separate Tanks or in One Tank With
Dr Amr Abdelkader San 419 94

48. Baffles
Train
Baffles Separate Each Contactor,
Dividing the Flow in the Train Into Separate
Complete Mix Zones of Treatment
Dr Amr Abdelkader San 419 95

49. Baffles
Train
Each Zone of Treatment is Called a
“Stage”
Dr Amr Abdelkader San 419 96

50. Baffles
Train
Stages
5
(Zones of Treatment)
Dr Amr Abdelkader San 419 97

51. 2 Trains
5 Stages
1st Stage
Effluent
Influent
When a System Has More Than One Train, Each Zone in the
System That Receives the Same Loading is Considered One
“Stage”
98

52. BOD, mg/L
100
60
39
25
18
STAGING
Staging Results in Significantly More Efficient
Treatment
Dr Amr Abdelkader San 419 99

53. STAGING
This Especially Important for Facilities that are
Required Nitrify Ammonia Dr Amr Abdelkader San 419 100

54. Egyptian Code
Dr Amr Abdelkader San 419 101

55. Dr Amr Abdelkader San 419 102

56. Dr Amr Abdelkader San 419 103

57. EXAMPLE
Calculate the organic and hydraulic loads
for the following RBC units
Plant Flow 3000m
3
/d
Trains in Service 2
Contactors in Each Train 5
Baffles Between All Contactor
Disc diameter 3.2 m, number of discs per group 120 discs
Primary Effluent Soluble BOD100 mg/L
:
Dr Amr Abdelkader San 419 104

58. Dr Amr Abdelkader San 419 105