NR 110.19(3)(a)(a) Recirculation. Recirculation shall be provided for intermediate and high-rate filters to increase treatment efficiency and to provide wetting of the biological growth. The recirculation rate shall be variable. The recirculation rate to average influent flow ratio should not exceed 4:1.
NR 110.19(3)(b)
(b) Dosing cycle. The interval between dosing cycles may not exceed one hour.
NR 110.19(3)(c)
(c) Flooding. Filter structures should be designed to allow flooding of the filter.
NR 110.19(3)(d)
(d) Primary treatment. Trickling filters shall be preceded by primary treatment facilities.
NR 110.19(4)
(4)
Design loading. Hydraulic and organic loadings to trickling filters may not exceed the values given in Table 4. Higher loadings may be approved if justified by pilot studies or if manufactured media is used. Higher loadings may also be used if the trickling filter is intended to act only as a roughing or polishing treatment unit.
NR 110.19(5)(a)1.1. Sewage shall be distributed over the filter by rotary distributors or other suitable devices which will permit uniform distribution to the filter surface area.
NR 110.19(5)(a)2.
2. Sewage shall be applied to the filters by siphons, pumps or by gravity discharge from preceding treatment units when suitable flow characteristics have been developed. The dosing rate shall be large enough to insure rotation of the distributor arms.
NR 110.19(5)(a)3.
3. A minimum clearance of 15 centimeters (6 inches) between media and distributor arms shall be provided.
NR 110.19(5)(b)1.1. An underdrainage system which covers the entire floor of the filter shall be provided. Inlet openings into the underdrains shall have an unsubmerged gross combined area equal to at least 15% of the surface area of the filter.
NR 110.19(5)(b)2.
2. The underdrains shall have a minimum slope of 1%. Effluent channels shall be designed to produce a minimum velocity of 60 centimeters per second (2 feet per second) at the average design flow of application to the filter including recirculated flows.
NR 110.19(6)(a)(a) Type. The media shall be crushed rock, slag or material specially manufactured for use as media in trickling filters.
NR 110.19(6)(b)1.1. Rock and slag media shall be durable, resistant to spalling or flaking, and be relatively insoluble in sewage. Slag media may not contain iron.
NR 110.19(6)(b)2.
2. Manufactured media shall be resistant to ultraviolet degradation, disintegration, erosion, aging, all common acids and alkalies, organic compounds, and fungus or biological attack. Either the media shall be structurally capable of supporting a person's weight or a suitable access walkway shall be provided to allow for distributor maintenance.
NR 110.19(6)(c)1.1. Rock, slag and similar media may not contain more than 5% by weight of pieces whose longest dimension is 3 times the least dimension. They shall be free from thin elongated and flat pieces, dust, clay, sand, or fine material and shall conform to the following size and gradings when mechanically graded over a vibrating screen with square openings:
NR 110.19(6)(c)2.
2. The department may approve other rock media gradations provided the gradations are consistent with accepted published engineering practices.
NR 110.19(7)(a)(a) Mercury seals. Mercury seals may not be used on trickling filter distributors. Mercury seals shall be removed from existing filters during renovation. Mercury seals removed from existing filters during renovation or destruction of the filter shall be disposed in a location and manner approved by the department.
NR 110.19(7)(b)
(b) Depth of media. Rock or slag filter media, or loose synthetic media, shall have a minimum depth of 1.5 meters (5 feet) above the underdrains. Synthetic corrugated filter media should have a minimum depth of 3 meters (10 feet) to provide adequate contact time with the wastewater. Rock or slag filter media depths may not exceed 3 meters (10 feet) and synthetic filter media depths may not exceed 9.1 meters (30 feet) except where special construction is justified through pilot studies.
NR 110.19(7)(c)
(c) Covers. Covers shall be provided on all filters to prevent icing and freezing and to increase the treatment efficiency of the filter during winter conditions.
NR 110.19(7)(d)1.1. The underdrainage system, effluent channels, and effluent pipe shall be designed to permit free passage of air. The size of drains, channels and pipe shall be such that not more than 50% of their cross-sectional area will be submerged under the maximum daily design hydraulic loading. The design of the effluent channels should consider the probability of increased hydraulic loading.
NR 110.19(7)(d)2.
2. Filter covers shall be designed to allow adequate ventilation to maintain the filter in an aerobic state at all times.
NR 110.19(7)(e)
(e) Maintenance. All distribution devices, underdrains, channels and pipes shall be installed so that they may be properly maintained, flushed and drained.
NR 110.19(7)(f)
(f) Flow measurement. Devices shall be provided to permit measurement of flow to the filter, including the amount of recirculated flow.
NR 110.19 History
History: Cr.
Register, November, 1974, No. 227, eff. 12-1-74; r. and recr.
Register, February, 1983, No. 326, eff. 3-1-83;
CR 09-123: am. (5) (b) 2. and (6) (b) 1.
Register July 2010 No. 655, eff. 8-1-10.
NR 110.20
NR 110.20 Rotating biological contactors. NR 110.20(1)(a)(a) Applicability. Rotating biological contactors may be used when the wastewater is amenable to biological treatment. This treatment process may be used for carbonaceous or nitrogenous oxygen demand reduction, or both.
NR 110.20(1)(b)
(b) Manufacturer's warranty. Manufacturers of rotating biological contactor equipment shall guarantee the rotating shafts, and media against failure during the initial 5 years of operation for all proposed rotating biological contactor treatment systems. The guarantee shall include equipment replacement and installation costs.
NR 110.20(2)(a)(a) Design report. A design report for rotating biological contactors shall be submitted in accordance with s.
NR 110.15 (1).
NR 110.20(2)(b)
(b) Design parameters. The design of rotating biological contactors shall consider:
NR 110.20(2)(b)2.
2. Influent carbonaceous and nitrogenous biochemical oxygen demand;
NR 110.20(3)(a)(a) Primary treatment. Rotating biological contactors shall be preceded by primary treatment.
NR 110.20(3)(b)1.1. Contact tanks shall be sized to maintain a maximum hydraulic detention time of 100 minutes.
NR 110.20(3)(b)2.
2. Tanks shall contain positive liquid level control so that the rotating biological contactors will remain approximately 40% submerged.
NR 110.20(3)(b)3.
3. Contact tanks and rotating shafts shall be enclosed. The enclosure shall be ventilated.
NR 110.20(3)(c)
(c) Equalization. Equalization facilities shall be provided ahead of rotating biological contactors if the ratio of maximum hourly design flow to average design flow exceeds 2.5:1.
NR 110.20(3)(d)
(d) High density media. High density shafts may not be used in the first 2 stages of any rotating biological treatment unit or system.
NR 110.20(3)(e)1.1. Contactors shall be equipped with drive units which will allow variable rotational speed.
NR 110.20(3)(e)2.
2. Maximum rotational speed shall be limited to a peripheral velocity of 49 centimeters per second (1.6 feet per second).
NR 110.20(3)(f)
(f) Load monitoring. Each rotating biological shaft shall be equipped with a load monitoring device.
NR 110.20 History
History: Cr.
Register, November, 1974, No. 227, eff. 12-1-74; r. and recr.
Register, February, 1983, No. 326, eff. 3-1-83.
NR 110.21(1)(1)
Applicability. The activated sludge process, and its various modifications, may be used where sewage is amenable to biological treatment.
NR 110.21(3)(a)(a) Process selection. The choice of activated sludge process will be influenced by the degree of treatment needed to achieve the required effluent limits, the proposed treatment facility size, and the characteristics of the waste to be treated.
NR 110.21(3)(b)
(b) Winter protection. Activated sludge processes and aeration equipment which are subject to freezing or icing shall be designed to minimize the degree of freezing and icing.
NR 110.21(3)(c)
(c) Pretreatment. Where primary settling tanks are not used, effective removal of grit, debris, excessive oil or grease, and comminution or screening of solids shall be provided prior to the activated sludge process.
NR 110.21(3)(d)
(d) Measuring devices. Devices shall be installed for measuring and displaying flow rates of raw sewage or primary effluent, return sludge, and air to the aeration facilities. It is recommended that these devices totalize and record, as well as indicate, flows if the average design flow for the treatment plant is greater than 5,680 cubic meters per day (1.5 million gallons per day).
NR 110.21(3)(e)
(e) Equalization. Equalization chambers shall be provided when large daily fluctuations of influent flow or organic loading are expected to occur.
NR 110.21(4)(a)(a) Process design. The size of aeration units for any particular adaptation of the activated sludge process shall be determined by pilot plant studies, or calculations based mainly on food to microorganism (F/M) ratio and mixed liquor suspended solids (MLSS) levels. Other factors such as size of treatment plant, diurnal load variations and degree of treatment required shall also be considered. In addition, temperature, pH bicarbonate hardness, and reactor dissolved oxygen shall be considered when designing for nitrification. The calculations used to determine the aeration capacity shall be included in the design report required by s.
NR 110.15 (1). Designs based on mixed liquor suspended solids levels greater than 5,000 milligrams per liter will not be approved unless adequate data is submitted showing the aeration and settling systems are capable of supporting such levels.
NR 110.21(4)(b)
(b) Permissible loadings. In lieu of the design calculation requirements of par.
(a), the parameters shown in Table 5 may be used to design aeration tank capacities. The volumetric loadings in Table 5 shall be based on the organic load influent to the aeration tank at the average design BOD
5 loading rate.
NR 110.21(4)(c)
(c) Number of units. Multiple aeration tanks shall be provided where the average design flow exceeds 1,890 cubic meters (500,000 gallons) per day.
NR 110.21(4)(d)1.1. The dimensions of each aeration tank or return sludge reaeration tank shall be such as to maintain effective mixing and use of air.
NR 110.21(4)(d)2.
2. Liquid depths in aeration tanks may not be less than 3 meters (10 feet). The department may allow liquid depths to exceed 5 meters (16 feet) on a case-by-case basis.
NR 110.21(4)(d)3.
3. Baffling or the placement of aeration equipment shall provide positive control of hydraulic short-circuiting through aeration tanks.
NR 110.21(4)(d)4.
4. Process piping, influent channels and inlet structure shall be arranged to provide operational flexibility.
NR 110.21(4)(d)5.
5. Inlets and outlets for each aeration tank unit shall be equipped with valves, gates, stop plates, weirs or other devices to permit controlling the flow to each tank and to maintain a constant liquid level. The hydraulic properties of the system shall permit the peak instantaneous design flow to be carried with any single aeration tank unit out of service.
NR 110.21(4)(d)6.
6. Channels and pipes carrying liquids with suspended solids shall be designed to maintain self-cleansing velocities or shall be agitated to keep the solids in suspension at all rates of flow within the design limits.
NR 110.21(4)(d)7.
7. All aeration tanks shall have a freeboard of not less than 46 centimeters (18 inches).
NR 110.21(5)(a)(a) General. The aeration system shall be capable of meeting the oxygen requirements of the activated sludge system, or of maintaining adequate mixing of the mixed liquor suspended solids, whichever is greater.
NR 110.21(5)(b)1.1. Aeration equipment shall be capable of maintaining a minimum mixed liquor dissolved oxygen concentration of 2 milligrams per liter.
