Installation guide

PROCEDURE FOR DE-SLUDGING

1. Remove 6” cover from de-sludging access point.

2. Carefully lower a 3” tanker hose down through the de-sludging access point until it rests on the bottom of the outer

tank (clariﬁer) or until the hose meets light resistance. Do not force the hose down further as this may damage the

internal workings of the unit. Depending on the invert level between 2.35m – 3.3m of hose is required to reach the bot-

tom of the tank from ground level.

3. Pump solids from the bottom of the outer tank. This will lower the liquid level in both the inner tank and outer tank

simultaneously.

4. As the liquid level drops, the scum layer between the inner tank and scum bafﬂe will normally break loose and drop

to the bottom of the tank where it can be sucked out. With a garden hose, ﬂush any remaining scum or residue to the

bottom of the tank.

5. Unless the plant is septic or there is an excessive scum build-up, it is not necessary to pump the system totally dry.

Leaving a small amount of sludge in the bottom (5-10 gallons) will reduce the normal start-up period.

6. In areas with a high water table, immediately re-ﬁll the tank with clear water to prevent shifting or ﬂoatation.

SLUDGE CHARACTERISTICS

It is important to observe the MLSS (mixed liquor suspended solids) sample, which is collected from the aeration chamber. As the

sample settles you should note the following:

1. What is the colour of the sludge?

2. Do the sludge particles clump together in a dense ﬂoc, that settles rapidly?

3. Is the liquid above the settled sludge (supernatant) clear?

4. Does the sample have a noticeable odour?

A good healthy sludge should have a chocolate brown colour. It should form a dense ﬂoc that settles rapidly leaving a clear, odour-

less supernatant. A sludge sample that has a grey black colour, settles slowly, has a cloudy supernatant containing very ﬁne, sus-

pended particles, usually indicates poor treatment plant operation. Therefore, it is important to compare your observations of the

plant as well as the sample of mixed liquor suspended solids to the conditions described in Appendix C and D attached to determine

if the plant is operating properly or if any corrective action needs to be taken.