Section R317-3-12 - Effluent Filtration12.1. 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 |
Utah Admin. Code R317-3-12