Download Winnaleah process overview

Winnaleah pilot plant trial – Process overview
TasWater is testing a membrane filtration process to improve the quality of drinking water supplied
to Winnaleah. The trial’s main objective is to demonstrate that lead can be removed from the raw
water supply using the membrane filtration process.
Membrane filtration is a natural process where the membrane acts as a physical filter allowing water
to pass through while separating the targeted undesirable compounds.
Membrane filtration applies to four separate sub-processes: microfiltration, ultrafiltration,
nanofiltration and reverse osmosis, as shown in the picture below. The difference between these
sub-processes is the pore size of the membrane.
Membrane filtration is being increasingly used in lieu of other fine solids separation processes such
as media filtration. This is because membrane filtration can provide finer separation and capture
100 per cent of the targeted colloids or suspended solids. In addition, membrane filtration does not
require addition of chemicals to the water as part of the treatment process and uses less energy
than alternative water treatment processes.
Tas Water has selected a HFW 1000 portable membrane filtration system for use at Winnaleah,
which was developed and manufactured by the company Pentair. The HFW 1000 is part of the latest
membrane technology and combines the excellent cleaning features of dead-end ultrafiltration with
the rejection properties of cross-flow nanofiltration.
The process used in the HFW 1000 system is generally considered to be highly efficient at removing
organics and ions carrying two charges or more (such as lead), and also offers the following
operational advantages:
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Robust system that is highly tolerant against feed water quality upsets
Constant high permeate quality
Substantial saving in space, cost and energy compared to other treatment technologies
Easily expandable
Reliable single barrier for bacteria and viruses.
The membrane ensures removal of all particulate matter including colloids, solids, bacteria, viruses,
cryptosporidium and Giardia oocysts. Dissolved matter is retained depending on material properties
such as molecular size, shape, charge polarity, etc. Therefore, the water produced after filtration
(called the permeate) is free of particles.
The waste water (called the retentate) generated by the membrane system contains only
concentrated organics and particulates, which were already present in the feed water and can be
discharged safely back into the environment without any further treatment.