Specifications

Rev: 12/08/04

IV. PUMPING

Bacteria and other microorganisms present in the wastewater use soluble organic material

as a food source, converting it into more microorganisms (biomass), water, and carbon dioxide.

As the colony matures, the numbers of microorganisms increase until they exceed the supply of

organic material to maintain them. Due to the resulting starvation, organisms will begin to die and

then be metabolized as new organisms are formed. Metabolized organisms reduce the overall

solids (or “sludge”) volume.

There will be a gradual increase in solids) due to the accumulation of inert remains of dead

organisms and non-degradable material in the wastewater. As the solids increase, the mixed liquor

becomes thicker, reducing the scouring effect on the filters. Periodically, the solids must be

pumped from the MULTI-FLO to prevent filter plugging and maintain adequate aeration within the

system.

PUMPING FREQUENCY:

The rate of solids accumulation—and resultant pumping—is dependent upon the quantity

and strength of wastewater entering the plant, i.e.; the greater the waste load, the more frequently

the MULTI-FLO should be pumped. Normally, residential systems should be pumped every 2-to-4

years. Units serving commercial occupancies may need to be pumped every 1-2 years, depending

on the waste load.

DETERMINING PUMPING FREQUENCY:

Trained service personnel can help owners establish a pumping frequency by performing a

24-hour settleable solids test of the mixed liquor during semi-annual service:

Procedure

1. Mark a quart jar into 10 equal portions

2. While aerator is running, fill the jar with mixed liquor suspended solids by lowering the jar

into the center aeration chamber.

3. Measure the percent of the original volume occupied by the sludge after it has settled for

24 hours.

The optimum level of settleable solids (24 hours) is normally between five and 50 percent.

Whenever the percent of settled sludge exceeds 50%, the unit should be pumped.

PROCEDURE FOR PUMPING THE MULTI-FLO:

1. Shut off the MULTI-FLO and allow solids to settle for 30-60 minutes.

2. Remove access cover and the surge bowl.

3. Lower the hose into the center aeration chamber. Care should be taken to avoid knocking or

damaging the aerator, air intake tubing or power cord. Be careful with the older model FTB 0.75

because the aerator sits on a platform.

4. Pump solids from the bottom. If the filters are not to be removed, be sure to hose down the

filters and the bottom of the hanger plate.