Annex 1
Background on the Ceramic Membrane Projects in PUB
Although ceramic membranes are widely used in industries, such as in food processing,
chemical, pulp and paper industries, its application in drinking water treatment and water
reuse sector is fairly new. Nonetheless, ceramic membranes offer several advantages over
polymeric membranes, including:

No fibre breakage

Long membrane life - >15 years

Very strong resistant to a wide range of cleaning chemicals

Withstand higher pressures up to 5 bar
Narrow pore size distribution
In addition, although the initial capital cost of ceramic membranes is comparable to
polymeric membranes, in the long run it might be a cheaper option as the lifespan of this
membrane is about 20 years - four times longer than a polymeric membrane.
The first pilot trial of the ceramic membrane technology in Singapore was conducted at
Bedok NEWater Factory from 2007 – 2009. The overall objective was to make a
comparative assessment of the performance of ceramic membranes for Reverse Osmosis
(RO) pre-treatment in water reuse application. The study indicated that coupled with a pretreatment coagulation process, the ceramic membrane had a better performance in terms of
Trans Membrane Pressure (TMP)1 and filtrate quality. A ceramic membrane performs its
best if ozone is further added into the system, something which is not possible to be
performed by a polymeric membrane due to its fragility. Ozone has multiple roles and
benefits in this case, it does not only stabilizes the TMP, it also destroys micro pollutants,
provides disinfections, and might be able to reduce fouling at downstream RO process.
However, as the scale of this test plant was rather small, this was only an indicative figure,
and the plant’s reliability and sustainability needed to be confirmed for large scale
operations.
1
The TMP curve is generally increasing and up to a certain level, the membrane needs to be cleaned. In plant
operations, a stable TMP is needed because the more stable the TMP is, the less energy required to pump out
the water, the less cleaning the membrane requires, which means less disruptions to membrane operations
(during chemical cleaning the membrane plant operation needs to be stopped), and less chemical usage.
For this reason PUB is moving forward with a nearly S$5 million ceramic membrane
demonstration plant at Choa Chu Kang Waterworks, in a joint study with PWN Technologies,
a Dutch utility and the inventor of a new ceramic membrane plant design2. With a capacity of
1,200,000 L/day, the plant will operate for a period of 18 months, during which PUB and
PWNT will conduct stringent performance testing and system optimisation.
For this project, PWN Technologies will be supported with a grant from the Technology
Pioneer (TechPioneer) Scheme, which is administered by the Environment and Water
Industry Programme Office (EWI). The Scheme aims to commercialise new technologies by
encouraging early adoption of these technologies by both the public and private sector in
their operations, promoting environmental sustainability at the same time. This will help
companies build a track record for these new technologies and expedite the
commercialisation of such technologies in the environment and water sector.
2 The
key design feature is that rather than having ceramic modules in individual stainless steel casings, up to
200 ceramic elements can now be housed in a single stainless steel vessel. This has reduced the capital cost
and operating cost by about 20% due to less stainless steel involved, less valves and other instrumentations, and
also less footprint required.
2