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Utah Administrative Code (Current through November 1, 2019) |
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R317. Environmental Quality, Water Quality |
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R317-3. Design Requirements for Wastewater Collection, Treatment and Disposal Systems |
R317-3-12. Effluent Filtration
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12.1. Granular Media Filters. Granular media filters may be used as a tertiary treatment device for the removal of residual suspended solids from secondary effluents. A pretreatment process such as chemical coagulation and sedimentation or other acceptable process must precede the filter units, where effluent suspended solids requirements are less than 10 milligrams per liter, or where secondary effluent quality can be expected to fluctuate significantly, or where filters follow a treatment process and where significant amounts of algae will be present.
12.2. Design Considerations. The plant design should incorporate flow-equalization facilities to moderate filter influent quality and quantity. The selection of pumping equipment ahead of filter units should be designed to minimize shearing of floc particles.
A. Filter Types. Filters may be of the gravity or pressure type. Pressure filters shall be provided with ready and convenient access to the media for treatment or cleaning. Where greases or similar solids which result in filter plugging are expected, filters should be of the gravity type.
B. Filtration Rates. Filtration rates shall not exceed 5 gallons per minute per square foot. (3.4 liters per square meter per second) based on the maximum hydraulic flow rate applied to the filter units.
C. Number of Units. Total filter area shall be provided in two or more units, and the filtration rate shall be calculated on the total available filter area with one unit out of service.
D. Filter Backwash
1. Backwash Rate. The backwash rate shall be adequate to fluidize and expand each media layer a minimum of 20 percent based on the media selected. The backwash system shall be capable of providing a variable backwash rate having a maximum of at least 20 gallons per minute per square foot, (13.6 liters per square meter per second) and a minimum backwash period of 10 minutes.
2. Backwash Pumps. Pumps for backwashing filter units shall be sized and interconnected to provide the required rate to any filter with the largest pump out of service. Filtered water should be used as the source of backwash water. Waste filter backwash shall be returned to the treatment process or otherwise adequately treated.
E. Filter Media
1. Selection. Selection of proper media size will depend on the rate of filtration rate, the type of pretreatment, filter configuration, and effluent quality objectives. In dual or multi-media filters, media size selection must consider compatibility among media.
2. Media Specifications. Table R317-3-12.2(E)(2) provides minimum media depths and the normally acceptable range of media sizes. The applicant has the responsibility for selection of media to meet specific conditions and treatment requirements relative to the project under consideration.
12.3. Filter Appurtenances. The filters shall be equipped with wash water troughs, surface wash or air scouring equipment, means of measurement and positive control of the backwash rate, equipment for measuring filter head loss, positive means of shutting off flow to a filter being backwashed, and filter influent and effluent sampling points. If automatic controls are provided, there shall be a manual override for operating equipment, including each individual valve essential to the filter operation. The underdrain system shall be designed for uniform distribution of backwash water (and air if provided) without danger of clogging from solids in the backwash water. Provision shall be made to allow periodic chlorination of the filter influent or backwash water to control slime growths.
12.4. Reliability. Each filter unit shall be designed and installed so that there is ready and convenient access to all components and the media surface for inspection and maintenance without taking other units out of service. The need for enclosing filter units shall depend on expected extreme climatic conditions at the treatment plant site. As a minimum, all controls shall be protected from adverse process and climatic conditions. The structure housing filter controls and equipment shall be provided with adequate heating and ventilation equipment to minimize problems with excess humidity.
12.5. Backwash Surge Control. The rate of waste filter backwash water return to treatment units shall be controlled such that the rate does not exceed 15 percent of the design average daily flow rate to the treatment units. The hydraulic and organic loads from waste backwash water shall be considered in the overall design of the treatment plant. Where waste backwash water is returned for treatment by pumping, adequate pumping capacity shall be provided with the largest unit out of service.
12.6. Backwash Water Storage. Total backwash water storage capacity provided in an effluent clearwell or surge tank or other unit shall equal or exceed the volume required for two complete backwash cycles. Additional storage capacity should be considered for operational flexibility.
12.7. Proprietary Equipment. Where proprietary filtration equipment, not conforming to the preceding requirements is proposed, data which supports the capacity of the equipment to meet effluent requirements under design conditions shall be submitted for review and approval by the Director.
TABLE R317-3-2.3(D)(4).
Minimum Slopes
Sewer Size, Minimum Slope,
inch (centimeter) feet per feet or
meter per meter
8 (20) 0.00334
9 (23) 0.00285
10 (25) 0.00248
12 (30) 0.00194
14 (36) 0.00158
15 (38) 0.00144
16 (41) 0.00132
18 (46) 0.00113
21 (53) 0.00092
24 (61) 0.00077
27 (69) 0.00066
30 (76) 0.00057
36 (91) 0.00045
TABLE R317-3-4.4(H)(1).
Painting
Service Color
Sludge Brown
Gas Orange
Potable Water Blue
Non-Potable Water Blue with a 6-inch (15 centimeters)
red band spaced 30 inches
(76 centimeters) apart
Chlorine Yellow
Compressed Air Green
Sewage Gray
TABLE R317-3-6.2(B)(3)(d).
Loadings for Final Settling Tanks
Following Activated Sludge Process
Process Average Surface Surface
Design Loading, Loading,
Rate of gallons per pounds
Flow, day per day
million per square per square
gallons foot foot
per day (cubic (kilograms
(cubic meters per day
meters per day per square
per day) per square meter)
meter)
Contact 0.5 (1,893) 400 (16.3)
Stabilization to 1.5 to 600
(5,678) (24.5)
Greater than 500 (20.4)
or equal to to 700
1.5 (5,678) (28.5)
Extended Less than 200 (8.2)
Aeration or equal to to 400
0.5 (1,893) (16.3)
0.5 (1,893) 300 (12.3) 25 (122.1)
to 1.5 to 500
(5,678) (20.4)
Greater than 400 (16.3)
or equal to to 600
1.5 (5,678) (24.5)
Other than Less than 400 (16.3)
Contact or equal to to 600
Stabilization 0.5 (1,893) (24.5)
and Extended
Aeration 0.5 (1,893) to 500 (20.4) 25 (122.1)
1.5 (5,678) to 700 (28.5)
Greater than 600 (24.5)
or equal to to 800
1.5 (5,678) (32.6)
TABLE R317-3-7.1(E)(3)(a)(2).
Media Grading
Percent by
Weight
Passing 4-1/2 inch (11.4 centimeters) screen 100
Retained on 3 inch (7.6 centimeters) screen 95 - 100
Retained on 2 inch (5.1 centimeters) screen 98
TABLE R317-3-7.1(K)(1).
Hydraulic and Organic Loadings
for Nitrification in Trickling Filters
Trickling Filter Configuration Loadings
Rock or Slag Media Filters
Hydraulic Loading Less than or equal
to 4 million gallons
per acre per day, or
less than or equal
to 4 cubic meters
per square meter per
day
Organic Loading Less than or equal
to 25 pounds BOD5
per day per 1000
cubic feet, or
less than or equal
to 0.4 kilograms
BOD5 per day per
cubic meter
Deep Manufactured Media Filters
Hydraulic Loading Less than or equal
to 25 million
gallons per acre per
day, or less than or
equal to 25 cubic
meters per square
meter per day
Organic Loading Less than or equal to 100
pounds BOD5 per day per
1000 cubic feet, or less
than or equal to
1.6 kilograms BOD5
per day per cubic meter
TABLE R317-3-7.2(B)(1)(c)
Permissible Aeration Tank Capacities and Loadings
Process Hydraulic Solids Aeration Food:Mass Mixed
Retention Retention Tank (F:M) Liquor
Time Time Loading, Ratio, Suspended
(HRT), (SRT), pounds of pounds of Solids (1)
hours days BOD5 per BOD5 per (MLSS)
day per day per milligrams
1000 pound of per liter
cubic MLVSS (2)
feet
Conven- 4-8 4-8 20-40 0.2-0.4 1,500-
tional 4,000
Step
Aeration
Complete
Mix
Contact 1-3 (4) 3-10 50 (3) 0.2-0.6 2,000-
Stabili- 3-6 (5) 4,000
zation
Extended
Aeration,
or 24 30 10-12 0.05- 2,000-
Oxidation 0.1 4,000
Ditch
Notes:
(1) Mixed Liquor Suspended Solids (MLSS) values are
dependent upon the surface area provided for sedimentation and
the rate of sludge return as well as the aeration process.
(2) Mixed Liquor Volatile Suspended Solids (MLVSS)
(3) Total Aeration capacity, includes both contact and
reaeration capacities. Normally, the contact zone equals 30 to
35 percent of the total aeration capacity.
(4) Contact zone
(5) Reaeration zone
TABLE R317-3-7.2(B)(6)(a)(1).
Return Sludge Rate
Process QR / Q, Percent
Standard Rate 15-75
Carbonaceous stage
of separate stage nitrification 15-75
Step Aeration 15-75
Contact stabilization 50-150
Extended aeration 50-150
Nitrification stage of
separate stage nitrification 50-200
TABLE R317-3-9.3(A)(1)(a).
Gravity Thickening
Type Solids Loading Rate, Percent solids
pounds per day per in thickened
square foot (kilograms sludge
per square meter
per day)
Primary sludge 20-30 (98-146) 8-10
Trickling filter sludge 8-10 (39-49) 7-9
Activated sludge 4-8 (20-49) 2.5-3
Combined primary and
trickling filter
sludges 10-12 (49-59) 7-9
Combined primary and
activated sludges 6-10 (29-49) 3-6
TABLE R317-3-9.4(A)(4)(a).
Sludge Volume Generated
Type of Plant cubic feet per Population
Equivalent (P.E.) or cubic
meters per Population
Equivalent (P.E.)
Trickling Filter 5 (0.14)
Activated Sludge 6 (0.17)
TABLE R317-3-10.3(G)(3)(a).
Circle of Influence
Nameplate Horsepower Radius, Feet
5 35
10-25 50
40-60 50-100
75 60-100
100 100
TABLE R317-3-12.2(E)(2).
Media Depths and Size
Media Material Single Media Multi-Media
Two Three
Anthracite:
Minimum Depth, inches 20 20
Effective Size, millimeters 1-2 1-2
Sand:
Minimum Depth, inches 48 12 10
Effective Size, millimeters 1-4 0.5-1 0.6-0.8
Garnet or Similar Material:
Minimum Depth, inches 2
Effective Size, millimeters 0.3-0.6
Uniformity Coefficient shall be less than or equal to 1.7