1. Primary Sedimentation
Jae K. (Jim) Park, Professor
Dept. of Civil and Environmental Engineering
University of Wisconsin-Madison 1

2. Primary Sedimentation
Objective: To remove settleable organic solids in large basins under relatively quiescent conditions
Removal efficiency
BOD5: 30~40%
TSS: 50~70%
Settled solids: collected by mechanical scrapers into a hopper, from which they are pumped to a sludge-processing area.
Oil, grease, and other floating materials: skimmed from the surface
Effluent: discharged over weirs into a collection trough
Types of primary sedimentation tanks
Horizontal flow
Solids contact
Inclined surface
Stacked or two-tray
Proprietary 2

3. Horizontal Flow Rectangular Sedimentation Tank3

4. Primary Sedimentation Tank4

5. Horizontal Flow Advantages
Occupy less land area when multiple units are used
Provide economy by using common walls for multiple units
Easier to cover the units for odor control
Provide longer travel distance for settling to occur
Less short-circuiting
Lower inlet-outlet losses
Less power consumption for sludge collection and removal mechanisms
Disadvantages
Possible dead spaces
Sensitive to flow surges
Restricted in width by collection equipment
Require multiple weirs to maintain low weir loading rates
High upkeep and maintenance costs of sprockets, chain, and flights used for sludge removal 5

6. Primary Sedimentation Tank
V-notched overflow weirs 6

7. Primary Sedimentation Tank Manual scum removal system7

8. Horizontal Flow Rectangular Sedimentation Tank
Longitudinal section with skimmer 8

9. 9

10. Horizontal Flow Rectangular Sedimentation Tank
Cross section 10

11. Horizontal Flow Sedimentation Tanks11

12. Horizontal Flow Rectangular Sedimentation Tank12

13. Horizontal Flow Rectangular Sedimentation Tank
V-notched overflow weirs 13

14. Horizontal Flow - continued
circular clarifier 14

15. Primary Sedimentation Basin
Scrubber for Odor Control
Odor Control Pipe
Covered Overflow Weir
Scum Collection Arm
Scum Removal Weir 15

16. Primary Sedimentation Tank16

17. Floating Inorganic Materials in Primary Sedimentation Tank17

18. Primary Sedimentation Tank Cover18

19. Inside of Covered Primary Sedimentation Tank
Too low
Potential maintenance problem during cleaning 19

20. Solids Contact
Incoming solids rise and come in contact with the solids in the sludge layer. This layer acts as a blanket, and the incoming solids agglomerate and remain enmeshed within this blanket. The liquid rises upward while a distinct interface retains the solids below.
Better hydraulic performance and shorter detention time for equivalent solids removal in horizontal flow clarifiers.
Either circular or rectangular
Not suitable for biological sludges because long sludge-holding times may create undesirable septic conditions. 20

21. Solids-Contact Clarifier21

22. Inclined Surface
Utilize inclined trays to divide the depth into shallower sections, which in turn results in significantly short settling time.
Frequently used to upgrade the existing overloaded primary and secondary clarifiers.
Tube settlers: use thin-wall tubes in circular, square, hexagonal, or any other geometric shape
Parallel plate separators: provide a large surface area, thereby reducing the clarifier size. Little wind effect, laminar flow, good for upgrading overloaded horizontal flow clarifiers
Disadvantages: septic condition, sludge sloughing off, and clogging of inner tubes and channels. 22

23. Inclined Plate Settlers23

24. Lamella Settlers 24

25. Design Factors
Design Objective: provide sufficient time under quiescent conditions for maximum settling to occur.
Conditions causing decrease in solids removal efficiency
Eddy currents induced by incoming fluid
Surface currents provided by wind action
Vertical currents induced by outlet structure
Vertical convection currents induced by the temperature difference between the influent and the tank contents
Density currents causing cold or heavy water to underrun a basin, and warm or light water to flow across its surface
Currents induced due to the sludge scraper and sludge removal system 25

26. Stacked or Two-Tray Sedimentation Basin26

27. Design overflow rates for sedimentation tanks (m3/m2·day)
Condition Range Typical
Primary sedimentation prior to secondary treatment
Average flow 30~50 40
Peak flow 70~
Primary sedimentation with WAS return
Average flow 25~35 30
Peak flow 45~80 60
Detention Times for Various Overflow Rates and Tank Depth
Overflow rate Detention period (hrs)
(m3/m2·day) 2-m 2.5-m 3-m 3.5-m 4-m 4.5-m
depth depth depth depth depth depth
Detention time at average design flow
Primary sedimentation tanks - 1~2 hrs
Secondary clarifiers - 2~4 hrs
1 m3/m2·day = gal/ft2·day 27

28. BOD5 and TSS Removal Efficiency with Respect to Overflow Rate and Detention Time28

29. Design Factors - continued
Weir loading rate (< 370 m3/m2·day) (Ten-States Standards)
124 m3/m2·day for plants designed for average design flow of  44 L/sec*
186 m3/m2·day for plants designed for average design flow of > 44 L/sec*
Dimensions
Type Range Typical
Rectangular
Length, m 10~100 25~60
Length-to-width ratio 1~7.5 4
Length-to-depth ratio 4.2~25 7~18
Sidewater depth, m 2.5~5 3.5
Width, m 3~24 6~10
Clarifier
Diameter, m 3~60 10~40
Side depth, m 3~6 4
Solids Loading
Not an important deciding factor for primary sedimentation tank design
Primary sedimentation tanks: 1.5~34 kg/m2·day
Secondary clarifiers: 49~98 kg/m2·day
* 44 L/sec = 1 MGD 29

30. Design Factors - continued
Influent structure
Dissipate energy in incoming flow by means of baffles or stilling basin
Distribute flow equally along the width
Prevent short circuiting by disturbing thermal and density stratification
Provide small head loss
Provision for flow control, scum removal, and maintenance
Velocity at inlet pipe: 0.3 m/sec 30

31. Influent Structures 31

32. Design Factors - continued
Effluent structure
Provide a uniform distribution of flow over a large area
Minimize the lifting of the particles and their escape into the effluent
Reduce the escape of
floating matter to the
effluent
Weir loading for plants
 44 L/sec – 124 m3/m·day
> 44 L/sec m3/m·day
Straight (1~2 mm head over
weirs – capillary clinging
effects – slime accumulation
or V-notches either one side
or both sides of trough
Baffle in front of the weir
to stop the floating
matter from escaping into
the effluent
Recommended 32

33. Design Factors - continued
Sludge collection
Bottom slope: to facilitate draining of the tank and to remove the sludge toward the hopper. Rectangular tanks: 1~2%; circular clarifiers: 40~100 mm/m (4~10%) diameter
Equipment
Rectangular tanks
A pair of endless conveyor chains running over sprockets attached to the shafts or moving-bridge sludge collectors having a scraper to push the sludge into the hopper
Suction-type arrangement to withdraw the sludge from basins
Circular tanks
Scraping mechanism with radial arms having plows set at an angle supported on center pier ( 10 m diameter) or on a beam spanning the tank (< 10 m diameter) (flight travel speed ~0.06 revolution/min)
Suction-type units for handling light sludge. 33

34. Conveyor Chain
One endless chain is connected to a shaft and a drive unit.
Linear conveyor speed is 0.3~1 m/min for primary and 0.3 m/min for secondary clarifier
Cross-wood (flights) (5 cm thick and 15~20 cm deep) are attached to the chain at 3-m intervals and are up to 6 m in length.
For tanks greater than 6 m in width, multiple pairs of chains are used.
The floating material is pushed in opposite direction of sludge and is collected in a scum collection box.
Advantages: simple to install, low power consumption, efficient scum collection, and suitable for heavier sludge
Disadvantages: high maintenance cost of chain and flight removal mechanism, dewatering of tanks for gear and chain repair, and potential resuspension of light sludge 34

35. Chain-and-Flight Sludge Collector
A. Chain
B. Sprockets
C. Shear pin
D. Chain tightener brackets
E. Wall bearings
P. Gear box
Q. Baffles
R. Flights (fiberglass or
wood)
S. Weirs
T. Scum pipe
F. Pillow block bearings
G. Sewage take-up bearing
H. Set collars
I. Screw conveyer
J. Shafting
K. Return rail system
L. Floor rail wear strip
M. Couplings
N. Wear shoes
O. Filler blocks 35

36. Bridge Drive Scraper
Standard traveling beam bridges for spans up to 13 m (40 ft) and truss bridge for spans over 13 span are used.
Bridge travel is accomplished by the use of a gear motor.
The wheels run on rails which are attached to the footing wall along each side wall of the basin.
Mechanical scrapers or rakes are hung from the top carriage that push the sludge to the hopper.
Separate blades are provided on top to move the scum.
Advantages: all moving mechanisms above water, scraper repair or replacement without dewatering tanks, no width restrictions, longer operation life, and lower maintenance cost in low-span bridges.
Disadvantages: high power requirement, not suitable for cold weather (ice formation in tanks), and frequent break-down due to wheel climbing over rails in long-span bridges. 36

37. Traveling Bridge Sludge Collector37

38. Bridge Drive Sludge Suction
The bridge design is similar to the bridge drive scraper.
The sludge removal mechanisms are attached to the bridge and provide continuous removal of sludge along the length of travel.
Pump, siphon, or airlift arrangements are used to suck and remove the sludge.
Advantages: Better pickup of light sludge, all moving mechanisms above water, scraper repair or replacement without dewatering tanks, no width restrictions, longer operation life, and lower maintenance cost in low-span bridges, and suitable for biological and chemical sludges.
Disadvantages: high power requirement, not suitable for cold weather (ice formation in tanks), and frequent break-down due to wheel climbing over rails in long-span bridges, and not used in primary sedimentation tanks. 38

39. Vacuum Sludge Removal Rectangular sedimentation basins
Southern States and warm climate areas
None freezing environments
Surface ice is difficult to design for. 39

40. Vacuum Sludge Removal 40

41. Design Factors - continued
Sludge Removal
Removed by means of a pump.
Design considerations
Provision of continuous sludge pumping is desirable.
Each sludge hopper should have individual sludge withdrawal line at least 15 cm in diameter.
In rectangular tanks, cross-collectors are preferred over multiple hoppers.
Screw conveyors for sludge removal are also used.
An automatic control of sludge pump or siphon pipes using a photocell-type or sonic-type sludge blanket detector is desirable, especially for secondary clarifiers.
The sludge pump used are self-priming centrifugal and normally discharge into a common manifold. One sludge pumping station can serve two rectangular sedimentation tanks. The circular clarifiers are normally arranged in groups of two or four. 41

42. Design Factors - continued
Scum removal
Generally pushed off the surface to a collection sump. In rectangular tanks, the scum is normally pushed in the opposite direction by the flights of the sludge mechanism in its return travel. In circular clarifiers, the scum is removed by a radial arm which rotates on the surface with the sludge removal equipment. Sometimes, removed by water sprays.
Scraped manually or mechanically up an inclined apron.
All effluent weirs have baffles to stop the loss of scum into the effluent.
The scum has a specific gravity of Solids content may vary from 25 to 60%.
The quantity of scum varies from 2 to 13 kg/103 m3 (17~110 lb/million gallon).
Pipings are often glass-lined and kept reasonably warm to minimize blockage.
Scum has been digested in aerobic and anaerobic digesters. 42

43. Scum Collection and Removal Arrangements43

44. Information Checklist
Average and peak design flows including the returned flows from other treatment units
All sidestreams from thickener, digester, and dewatering facility
Treatment plant design criteria prepared by the concerned regulatory agencies
Equipment manufacturers and equipment selection guide
Information on the existing facility if the plant is being expanded
Available space and topographic map of the plant site
Shape of the tank (rectangular, square, or circular)
Influent pipe data, to include diameter, flow characteristics, and approximate water surface elevation or hydraulic grade line
Headloss constrains for sedimentation facility 44

45. Design Calculations Design criteria
1. Two rectangular units shall be designed for independent operation. Allow for a bypass to secondary treatment process when one unit is out of service.
2. Overflow rate and detention times shall be based on an average design flow of 0.44 m3/sec (10 MGD).
3. The overflow rate shall be < 36 m3/m2·day at average design flow.
4. The detention time shall be > 1.5 hrs at average design flow.
5. The influent structure shall be designed to prevent short circuiting and reduce turbulence. The influent channel shall have a velocity < 0.35 m/sec at design peak flow (0.661 m3/sec through each basin).
6. All sidestreams shall be returned to aeration basins.
7. The weir loading shall be < 186 m3/m·day at average design flow and < 372 m3/m·day at design peak flow.
8. The launder and outlet channels shall be designed at the peak design flow of m3/sec (0.661 m3/sec through each basin).
9. The average liquid depth in the basin shall be > 3 m.
10. The slope of the tank bottom shall be 1.35% (1~2% in slide #33). 45

46. Design Calculations - continued
Basin dimensions
1. Select basin geometry and provide two rectangular basins with common wall
Average design flow through each basin = 0.44/2 = 0.22 m3/sec
Overflow rate at average design flow = 36 m3/m2·day
Surface area = 0.22 m3/sec × 86,400 sec/day  36 m3/m2·day
= 528 m2
Use length-to-width ratio (L:W) = 4:1 ~ OK
4W × W = 528 m2; W = 11.5 m; use W = m (38 ft) due to ft increments for sludge collectors.
Thus, length = m (152 ft).
Depth at mid-length of the tank = 4 m (13.1 ft)
Length-to-depth ratio = m/4 m = 11.6 ~ OK
Freeboard = 0.6 m (2 ft)
Average depth of the basin = 4.6 m (15 ft) 46

47. Design Calculations - continued
2. Check overflow rate
Overflow rate at average design flow = 0.22 m3/sec × 86,400
sec/day  (11.58 m × m) = 35.4 m3/m2·day
Overflow rate at peak design flow = m3/sec × 86,400
sec/day  (11.58 m × m) = m3/m2·day
3. Check detention time
Average volume of the basin = 4 m × m × m
= 2,146.0 m3
Detention time at average design flow = 2,146.0 m3  (0.22 m3/sec
× 3,600 sec/hr) = 2.7 hrs ⇒ > 1.5 hrs ~ OK
Detention time at peak design flow = 2,146.0 m3  (0.661 m3/sec
× 3,600 sec/hr) = 0.9 hr
Influent structure
1. Select the arrangement of the influent structure
The influent structure includes a 1-m wide influent channel that runs across the width of the tank. Eight submerged orifices 34 cm square each, are provided in the inside wall of the channel. 47

48. Design Calculations - continued
A submerged influent baffle is provided 0.8 m in front, 1 m deep, and 5 cm below the liquid surface.
Why?
Potential constructability issue
To prevent settling 48

49. Design Calculations - continued
2. Compute the headloss in the influent pipe connecting the junction box located downstream of the grit chamber and the influent structure of the sedimentation basin
The elevation of the water surface in the influent channel of the basin is lower than that in the junction box downstream from the grit chamber. H is the sum of the headloss in the connecting pipe due to the entrance, friction, bends, and fittings and exit loss into the influent channel of the sedimentation basin. 49

50. Design Calculations - continued
3. Compute the headloss at the influent structure
The horizontal velocity in the sedimentation basin (v2) is small and is ignored. The average velocity in the influent channel (v1) is calculated at peak design flow. Half of the flow divides on each side of the basin.
The depth of water into the influent channel is fixed by the designer. Assume the depth of water at the entrance of the influent channel is 1 m and the width of the influent channel is 1 m.
z = hL; Q = CdA
< 0.35 m/sec ~ OK
See slide #48
See slide #48 50

51. Design Calculations - continued
Effluent structure
1. Select the arrangement of the effluent structure
The effluent structure consists of weirs, launder, an outlet box, and an outlet pipe. Use V-notched weir.
2. Compute the length of the weir
Weir loading = 372 m3/m·day at peak design flow
Peak design flow per basin = m3/sec × 86,400 sec/day
= 57,110 m3/day
Weir length = 57,110 m3/day  372 m3/m·day = m
Provide weir notches on both sides of the launder. Thus,
Total length of the weir plate = 2( ) m + 2( )
m - 1 m = m
Actual weir loading = 57,110 m3/day  m
= m3/m·day ≈ 372 m3/m·day at peak flow → OK
3. Compute the number of V-notches
Provide 90° standard V-notches at a rate of 20 cm center to center on both sides of the launders. 51

52. Weir Arrangement 52

53. Design Calculations - continued
Total number of notches = 5 notches per m × m = 769
In order to leave sufficient space on the ends of the weir plate, provide a total of 765 notches. 53

54. Design Calculations - continued
4. Compute the head over the V-notches at the average design flow
The average discharge per notch at average design flow
= 0.22 m3/sec  765 notches = 2.88 × 10-4 m3/sec per notch
The discharge through a V-notch is calculated using the eq. below.
Q = 8/15 Cd 2g ·tan(/2) H5/2
where Cd = 0.6, H = head over notch, m, and  = angle of the V-
notch = 90°.
2.88 × 10-4 m3/sec = 8/15 × 0.6 × 2 ×9.81 m/sec2·tan (90/2) H5/2
H = 0.03 m = 3 cm
5. Compute head over V-notches at peak design flow
Discharge per notch at peak design flow
= m3/sec  765 notches = 8.64 × 10-4 m3/sec per notch
8.64 × 10-4 m3/sec = 8/15 × × 2 ×9.81 m/sec2·tan (90/2) H5/2
H = 0.05 m = 5 cm
6. Check the depth of the notch
The total depth of the notch is 8 cm. Max. liquid head over the notch at peak design flow is 5 cm (safe allowance of 3 cm). 54

55. Design Calculations - continued
7. Compute the dimensions of the effluent launder
Width of the launder, b = 0.6 m
Width of the effluent box = 1.0 m
Diameter of the outlet pipe = 0.92 m
The depth of water in the effluent box = 1.0 m (fixed by designer)
Provide the invert of the effluent launder 0.46 m above the invert of the effluent box
Depth of water in the effluent launder at exit point y2
= 1.0 m m = 0.54 m
Critical depth of flow in the launder
Since 0.54 m > 0.5 m, the outfall is submerged.
Half of the flow divides on each side of the launder
Flow on each side of the launder = m3/sec  2 = 0.33 m3/sec 55

56. Weir Trough (Launder) Values given by designer Section AA
In slide #53, cm - 5 cm = 3 cm
Thus,
1.45 m m = 1.48 m
Section CC 56

57. Effluent Launder Water Surface Profile
Δz=hL = 1.45 m m
= 0.91 m
(10.38 m – 1 m)/2 = 4.69 m
Section BB 57

58. Outlet Channel
4.02 m – 0.91 m – 0.54 m =
= 4.02 m – 0.91 m 58

59. Design Calculations - continued
Q’ = m3/s  2 = 0.33 m
Generally, an allowance for losses due to friction, turbulence, and bends is 10~30%. In this case, provide a 25% allowance, and add 0.6 m for freefall.
Water depth at the far end of trough = 0.64 m × 1.25 = 0.80 m
Total depth of the effluent launder = 0.80 m m = 1.40 m
Headloss through sedimentation basin
Headloss at the influent structure (calculated) = 0.07 m
Headloss at the effluent structure (calculated) = 0.91 m
Headloss in the basin (small - ignored)
Headloss at the influent and effluent baffles (small - ignored). 59

60. Design Calculations - continued
Hydraulic profile through the basin
A total headloss of 0.98 m (3.25 ft) (= 4.09 m m) at the peak design flow.
= 2.57 m m 60

61. Design Calculations - continued
Sludge Quantities
1. Establish sludge characteristics
Primary sludge: specific gravity of 1.03 and a solids content of 3~6%. Assume a typical solids content of 4.5%.
2. Compute average quantity of sludge produced per day
Amount of solids produced per basin per day at a removal rate of 63% = 260 g/m3 × 0.63 × 0.22 m3/sec ×86,400 sec/day
× kg/1,000 g = 3,113.5 kg/day
Average quantity of sludge produced per day from both basins
= 2 × 3,113.5 kg/day = 6,227 kg/day
3. Compute the volume of sludge produced per minute per basin
Volume of sludge at specific gravity of 1.03 and 4.5% solids
= 3,113.5 kg/day  (1.03 × 1 g/m3 × 1 kg/1,000 g × ×
106 cm3/m3 × 1,440 min/day) = m3/min per basin
4. Determine sludge pump size and pumping cycle
Provide separate sludge pumps for each basin. Arrange such that each pump will serve both basins in case one pump is out of service. 61

62. Design Calculations - continued
Operate each pump on a time cycle, at 16.5-min intervals with a 1.5-min pumping cycle per basin (total time 18 min per cycle)
The desired pumping capacity of the pump = ( m3/min per
basin × 18 min per cycle)  1.5 min pumping per cycle
= 0.56 m3/min per basin (150 gpm)
When one pump is used to remove the sludge from two basins, the cycle time will be reduced.
Cycle interval in min for two basins
= ( ) min  2
= 9 min per cycle
Effluent quality from primary
sedimentation basin
1. Establish BOD5 and TSS removal
At overflow rate of 35.4 m3/m2·day,
BOD5 removal = 34%
SS removal = 63% 62

63. Design Calculations - continued
2. Compute BOD5 and TSS in the effluent
Assume the sidestreams from the thickeners, digesters, and dewatering facilities are returned to the aeration basin.
BOD5 in the primary effluent = 250 g/m3 × ( ) × 0.44
m3/sec × 86,400 sec/day × kg/1,000 g = 6,273 kg/day
TSS in the primary effluent = 260 g/m3 × ( ) × 0.44
m3/sec × 86,400 sec/day × kg/1,000 g = 3,657 kg/day
Volume of primary effluent = Average flow to primary - Sludge
withdrawal = 0.44 m3/sec × 86,400 sec/day - (6,227 kg/day
× 1,000 g/kg)  (0.045 g/g × 1.03 × g/cm3 × 106 cm3/m3)
= 38,016 m3/day m3/day = 37,882 m3/day
BOD5 conc. in effluent = 6,273 kg/day  37,882 m3/day × 1,000
g/kg = g/m3 = mg/L
TSS conc. in effluent = 3,657 kg/day  37,882 m3/day × 1,000
g/kg = g/m3 = 96.5 mg/L
Scum quantity: ave. quantity of scum (S.G.=0.95) =
8 kg/1,000 m3 × 38,016 m3/day = 304 kg/day = 0.32 m3/day 63

64. Layout of the Primary Sedimentation Basins64

65. 65

66. Common Operating Problems
1. Black and odorous septic wastewater due to decomposing wastewater in the collection system, recycle of excessively strong digester supernatant, or inadequate pretreatment of organic discharges from the industries  preaeration, chlorination, or hydrogen peroxide/ potassium permanganate oxidation, control of digester supernatant, and strict enforcement of industrial pretreatment regulations
2. Scum overflow due to inadequate frequency of scum removal, excessive industrial contribution, worn or damaged scum wiper blades, or improper alignment of the skimmer
3. Sludge that is hard to remove from the sludge hopper due to excessive grit accumulation  check the grit removal facility
4. Low solids in the sludge due to excessive sludge withdrawal, short circuiting, or surging flow
5. Excessive corrosion of metals due to H2S gas
6. Frequent broken scraper chain and shear pin failures due to improper shear pin sizing and flight alignment, ice formation, or excessive loading on the sludge scraper
7. A noise chain drive or a loose or stiff chain due to misalignment 66

67. Operation and Maintenance
1. Remove accumulations from the influent baffles, effluent weirs, scum baffles, and scum box each day.
2. Inspect all mechanical equipment at least once each shift.
3. Hose down and remove wastewater sludge and spills ASAP.
4. Determine sludge level and underflow concentration, and adjust primary sludge pumping rate accordingly.
4. Observe operation of scum pump and provide hosing as necessary.
5. Check daily electrical motors for overall operation, bearing temperature, and overload detector.
6. Check oil levels in gear reducers and bearings on a regular basis.
7. Drain each primary basin annually and inspect the underwater portion of the concrete structure and all mechanical parts.
8. Inspect all mechanical parts for wear, corrosion, and set proper clearance for flights at tank walls.
9. Clean and paint the exposed metal surfaces as necessary. 67

68. Specifications General
Include a complete assembly of a sludge collector mechanism with drive and collector chains with flights, access bridge and walkway, influent and effluent structures, pumping facilities, and overload alarm system.
Dimensions: # of basins (identical basins with common wall), Length, width, side wall depth (SWD) at effluent end, influent end, and mid length, bottom slope, free board, etc. 68

69. Specifications - continued
Materials and Fabrication
Conform to proper ASTM standards. The min. thickness of all submerged metal shall not be < 0.64 mm (1/5 in) and of all-above water metal 4.8 mm (3/16 in). Conform to all American Institute of Steel Construction (AISC) standards for structural steel buildings.
Collectors
Provide two longitudinal collectors and one cross-collector in each basin
Dimensions, numbers, and materials of flights, sprocket wheels, scrapers, chains, etc. 69

70. Specifications - continued
Drive Unit
Consists of a gear motor, gear reducer, drive base, shear pin coupling, overload alarm device, and drive sprocket and chain
Motor and gear – detailed specifications
Sludge Pump
Self-priming, centrifugal, and nonclogging, pumping rate, etc.
Effluent Weir
V-notch weir and effluent box dimensions, scum removal, etc.
Skimmer
Hand-operated adjustable scum trough
Painting
Primed and painted with approved paint or epoxy 70