Basic needtoknow for MultiFlo pretreatment systems Specific requirements

Basic “need-to-know” for Multi-Flo pretreatment systems. Specific requirements for MN applications.

Multi-Flo Basics The Multi-Flo is an Aerobic Treatment Unit, or ATU. Multi-Flo units come in a variety of sizes, the FTB. 5, FTB. 6 & FTB. 75 are Minnesota registered with residential strength waste to 500, 600 & 750 gpd respectively. Each of these units will achieve treatment Level “A” with a UV lite. Treatment level “A” only requires 12” of separation to the seasonal high water table and receives an average 25% reduction of the drainfield size. Check the “treatment level A” soil loading rates for your specific soil. The Multi-Flo system is reasonably priced, but like most ATU’s you must be aware of the increased monthly electric bill that comes with it. The power cost is often an additional $20 a month for the constantly running blower motor.

The 600 gpd Multi-Flo unit is 86” high (75” burial depth) and 71” in diameter. It weighs about 420 lbs dry.

The basic layout of the Multi-Flo system is similar to a standard pressure bed. To better understand this concept, a typical layout is shown on the following slides:

Standard pressure bed layout Drain field Septic Drawing #1 Lift

Now simply insert a Multi-Flo unit between the septic and lift tanks, and reconfigure the septic tank to a trash trap/dosing tank.

Additional pretreatment component, and tank conversion Drain field Trash trap / Dose tank Drawing #1 Multi-flo Lift

Treatment The pump in the trash tank doses the Multi-Flo by pumping 5 -10 gallons into the center of the unit every 30 minutes. The aerator in the unit mixes and provides oxygen to treat the effluent. The “blower/mixer” inside the unit draws air from the outside and as such there is no external blower housing.

water flow The small doses enter the center aeration chamber and then slowly up-flow through the sock filters. As the water rises outside of the center area, it then flows over the weir and out of the unit.

Each Multi-Flo unit is installed so that the top of the unit will be above final grade. This provides easy access to the unit for maintenance.

For MN treatment level “A”, the Multi-Flo must be followed with a UV light. The UV light is required to be inspected and cleaned twice a year. The bulb is recommended to be replaced every 2 years. MN 7080 does not require lab sampling on any registered Type IV pretreatment system, but some local operating permits may require at least a fecal test to confirm treatment is occurring as intended. Check with your local unit of government for their specific requirements. Salcor UV lite

MN 7080 requires “treatment level A” effluent to be: - time dosed and - uniformly distributed. This typically results in using a standard pressure bed or pressure trenches. You must be at least an Intermediate designer to design a residential strength Type IV pretreatment system < 2500 gpd. An operating permit and a management plan are also required.

Install tips During the installer site visit, it is a good time to confirm the placement of the control panel. It is best to place it near the Multi-flo, between the trash tank and lift tank. The panel will control: - the time dosed pump in the trash tank, and the high level alarm, - power the aeration motor in the Multi-flo, the blower alarm, and the high level alarm, - control the lift pump in the dose tank, and the high level alarm, - and power the UV lite.

The Multi-flo system has some flexibility in regards to the depth of the trash tank. The Multi-flo unit is typically dosed by pumping up to the unit, but you do have the option to pump down if necessary.

To reduce odors the inlet pipe can be extended down until it is below the water surface. (when pumping DOWN to the unit)

When pumping UP to the unit, the inlet pipe will still continue until it is below the water surface, but it must first go through a “J” hook assembly with an air inlet at the high point to prevent siphoning. “J” hook must be higher than the high level alarm sensor.

The Multi-Flo must be set level to ensure the weir is level. This way the effluent flows over ALL the weir and not in just one spot (which would defeat the purpose). You must fill the unit with water while backfilling. Make sure the backfill is reasonably compacted so settling does not shear off the inlet and outlet pipes.

This is the riser to the lift tank. The UV lite is typically installed here and is shown with an angled pipe fitting. This helps makes room for the float tree and lift pump to all be in the same riser.

Design worksheet When designing any system, the simplest method is to find the appropriate design worksheet at www. Septic. Resource. com and fill it in with the basic field data you obtained from your site evaluation. The design worksheet for a pretreatment system will still only take a couple of minutes to complete. Multi Flow & Pressure Bed 2011 purple code www. Septic. Resource. com (vers 14. 2) Property Owner: Date: Site Address: PID: Comments: = adjust if desired = self-calculated (DO NOT ADJUST) instructions: = site specific input 1) ? bedroom 0 GPD design flow (average flow should be < 70% of design flow) PRETREATMENT: (Residential strength to level A/B) Type IV Residential System 2) 3) 1000 Gallon Trash trap/pump tank to Multi-flow 500 Gallon Multi-flow unit 30 gpm 10 feet of 4) UV light req'd Yes 5) 10 ft head 2. 0 TREATMENT pump inch supply line leads to 48 doses per day 2 gallons of drainback volume gallons total pump out volume 2. 0 0. 0 gal /dose (treatment)

The design sheet will also produce a System elevation template

System summary - The Multi-Flo units are registered at different flow capacities: 500, 600, 750 & 1000+ gpd. - The trash tank is sized for 50 -100% of the Multi-flo capacity, if a larger tank is used just keep the operating level lower as to not exceed 1 days retention. - Small pump doses keep the surges over the weir to a minimum, which lowers the amount of suspended solids reaching the drainfield. - Fill the unit to the operating level at install to properly backfill and also avoid floatation issues. - The UV lite is typically set in the lift tank riser. - Be aware of placement in regards to potential odors coming from the exhaust vent at the top lid.

System summary - The unit has a 6 -8 week start up period. Occasional pumping is required about every 3 years. With the system running, fill a quart jar with mixed liquor and let it settle 24 hours. Optimal level of settled solids is between 5 and 50% , greater than 50% requires a unit pumping. During pumping leave about one foot of water to “seed” the system, otherwise it will take another 6 -8 weeks for the start-up process to complete. - Avoid grease and water softener backwash. - Aerator replacement about every 4 years. - Normal operation: aeration tank is light to medium brown and clear effluent.

Typical beneficial applications Often a small lake lot does not have room for a standard system or even a down sized type III mound. In this situation you may have around 18” to SHWT. With a level “A” pretreatment system you can eliminate the need for a mound and reduce the size of the required drainfield footprint. With 12” of soil for treatment and roughly 6” of distribution rock, the top of rock elevation is basically back to grade. When the additional 12” of cover above grade is blended in to the existing grade, you often can’t tell where the drainfield is. This can be achieved with a pressure bed or using pressure trenches down a slope. With the Multi-Flo unit taking less space than a small septic tank, this and the lift tank do not require a lot of additional yard space. Since these components are all at grade, the owners often simply landscape around the lids. The end result is a minimal impact to the yard which is quite a contrast to putting in a 3’ high (minimum) finished grade mound. If you have room for a few small tanks and a small drainfield, this system will work well.

Components landscaped with rock and bushes

This concludes the basic Multi-Flo “need to know” training. For further information contact your local distributor or the manufacturer at www. consolidatedtreatment. com