Utah Administrative Code
Topic - Environmental Quality
Title R317 - Water Quality
Rule R317-3 - Design Requirements for Wastewater Collection, Treatment and Disposal Systems
Section R317-3-12 - Effluent Filtration

Universal Citation: UT Admin Code R 317-3-12

Current through Bulletin 2024-06, March 15, 2024

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, inch (centimeter)

Minimum Slope, feet per feet or m e t er 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 Design Rate of Flow, million gallons per day (cubic meters per day)

Surface Loading, gallons per ay per square foot (cubic meters per day per square meter)

Surface Loading, pounds per day per square oot (kilograms per day per square meter)

Contact Stabilization

0.5 (1,893) to 1.5 (5,678)

400 (16.3) to 600 (24.5)

Greater than or equal to 1.5 (5,678)

500 (20.4) to 700 (28.5)

Extended Aeration

Less than or equal to 0.5 (1,893)

200 (8.2) to 400 (16.3)

0.5 (1,893) to 1.5 (5,678)

300 (12.3) to 500 (20.4)

25 (122.1)

Greater than or equal to 1.5 (5,678)

400 (16.3) to 600 (24.5)

Other than Contact Stabilization and Extended Aeration

Less than or equal to 0.5 (1,893)

400 (16.3) to 600 (24.5)

0.5 (1,893) to 1.5 (5,678)

500 (20.4) to 700 (28.5)

25 (122.1)

Greater than or equal to 1.5 (5,678)

600 (24.5) to 800 (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 1 0 0 0 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 Retention Time (HRT), hours

Solids Retention Time (SRT), days

Aeration Tank Loading, pounds of BOD5 per day per 1000 cubic feet

Food:Mass (F:M) Ratio, pounds of

BOD5 per day per pound of MLVSS (2)

Mixed Liquor Suspended Solids (1) (MLSS) milligrams per liter

Conventional

4-8

4-8

20-40

0.2-0.4

1,500 - 4,000

Step Aeration

Complete Mix

Contact

Stabilization

1-3 (4)

3-6 (5)

3-10

50 (3)

0.2-0.6

2,000 - 4,000

Extended Aeration, or Oxidation Ditch

24

30

10-12

0.05 - 0.1

2,000 - 4,000

Note:

(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, pounds per day per square foot (kilograms per square meter per day)

Percent solids in thickened sludge

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

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