Until recently, turbidity
testing at the Pontsticill
Water Treatment Works in
the Brecon Beacons National
Park relied on the use of
bellows pump technology.

However, the inherent
introduction of air in the
samples was undesirable and
led to false readings.Now,
Watson-Marlow’s Qdos 30
metering pumps provide
good suction lift and do so
without air locks.

“This is a clean water site
and the quality of sample is
very important,” states Marek
Cegielski, a process scientist
and manager at Dwr Cymru
Welsh Water. “In the past
we’ve tried other types of
turbidity monitoring devices,
such as dip probes, but
without much success. We’ve
even used bubble traps in
conjunction with our bellows
pumps, but we still fell short
of 100% reliability. Of course,
eliminating the need for
bubble traps was one of the
attractions of replacing one
of our bellows pumps with
the new Qdos 30 from
Watson-Marlow.”
The Qdos 30 metering
pump at Pontsticill is taking
elutriates from a DAF
(dissolved air flotation)
filtration plant and lifting it
about 3m before it passes
through a turbidity meter
and returns by gravity back
into the flow. At this point
the water has already been
subjected to coagulation,
flocculation and flotation,
and is ready for final
filtration processes.

Capable of delivering flow
performance from 0.1 to
500ml/min, the pump gives
the water company a steady
flow speed of 280ml/min.