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Newsletter for TRILITY Group and Joint Venture clients
Empty IDEA Cell, waiting for cleaning
What’s involved in the replacement of diffuser pads
Like all equipment, maintenance is a given. After 15 years of near-continuous
service, the rubber pads in the diffusers of the Intermittent Decanted Extended
Aeration (IDEA) cells at our Echuca Wastewater Treatment Plant had reached
their expiry date.
Through routine inspections, our operations team scheduled the replacement
of the pads. The team set about planning the changeover, with IDEA cell two
being chosen to be emptied due to a damaged boot on the outlet pipe and a
damaged valve that could not be changed without fully emptying the cell.
The process is both time-consuming and complex.
The changeover process commenced with the cell being drained of part of
the contents, some of which were sent out to the drying beds, and the thick
sludge being pumped into the sludge digester over the course of a week. Next,
some time was spent hosing down and cleaning the cell floor at the outlet end,
followed by removing the diffusers to clear the area for two scissor lifts.
The lifts were used in tandem over the course of a day; the boot was changed,
and the diffusers were put back in preparation for changing the diffuser pads.
The process of changing the pads, while considered simple, is very time
consuming because of the sheer volume of diffusers. There are approximately
2500 diffusers per cell, and this involves the undoing of the PVC ring holding
each of the pads in place, the removal of each pad and the plate underneath,
then scrubbing clean the PVC parts, lubricating the edges of the new pads, and
then putting everything back together again. Once complete, the team filled
the cell to just over the diffuser level; to identify any air leaks, it was essential
to ensure there were no leaks before completely refilling the cell. Where an air
leak was found, it had to be resealed. This was done manually with someone
carefully walking out in waders and blindly tightening the seals where the leak
had been located, which was challenging in the slippery, sludgy, muddy water.
The Echuca operations team aimed to get a row and a half of diffusers done per
day; the process took over a month to complete. The team are now scheduling
the same approach across the plant’s remaining cells.
To find out more, email us at info@trility.com.au
Dropping one of the scissor lifts into the cell
Changing the diffuser pads in IDEA Cell 2