PuK - Process Technology & Components 2024

Pumps and Systems
Peristaltic pumps
Metering of flocculants in drinking water treatment
“Peristaltic pumps are an economical solution“
Surface water from reservoirs plays
an important role in the drinking
water supply. Flocculation and filtration
of colloidal particles is one
of the central process steps in the
purification process of turning raw
water into drinking water. Metering
pumps for flocculants must therefore
meet the highest standards in
terms of durability and operational
reliability. For this reason, Thüringer
Fernwasserversorgung (TFW) relies
on Qdos peristaltic metering
pumps from Watson-Marlow in the
Luisenthal treatment plant. These
pumps not only impress with their
simple installation, operation, and
low pulsation, but provide long operating
times and easy maintenance
in just a few minutes. This results in
a highly economic solution.
With an annual delivery volume of
36.9 million m³ of drinking water,
Thüringer Fernwasserversorgung (TFW)
is one of the largest suppliers of longdistance
drinking water in Germany.
The public company TFW supplies
drinking water to municipalities, municipal
associations and municipal
utilities via long-distance water pipelines
with a total length of around
550 km, thus ensuring the drinking
water supply of more than one million
inhabitants in the German state
of Thuringia together with the local
supply companies.
TFW is the only German longdistance
water supplier to exclusively
provide surface water from six of
its own drinking water reservoirs. It
operates two modern and efficient
drinking water treatment plants to
process the surface water (raw water)
into drinking water.
Surface water as drinking water
The importance of surface water for
securing the drinking water supply
should not be underestimated. Already
today, a total of 55 % of total
drinking water demand in Thuringia
is supplied from reservoirs and their
relevance for drinking water is likely
to increase further in times of climate
change, as current research shows
Fig. 1: The Luisenthal plant, located at the Ohra water reservoir processes raw into drinking
water – circa 21.5 million m³ per year.
that reservoirs have a higher resilience
to climate change than groundwater
supplies. Due to the more frequent
occurrence of local extreme
weather conditions such as heavy
rainfall, heatwaves and dry spells associated
with climate change, longdistance
water supplies are also likely
to play a particularly important role in
ensuring a secure drinking water supply
through efficient water management
in the future.
Located in the Thuringian Forest
Nature Park, the Ohra reservoir managed
by TFW has a maximum storage
capacity of up to 17.82 million
m³. The raw water is extracted at different
heights via an extraction tower.
Around 700,000 people, including
those in the cities of Jena and Erfurt
and the nearby district town of Gotha,
are supplied daily with water from the
dam via the North and Central Thuringia
long distance water supply system.
Around 21.5 million m³ of raw
water from the Ohra reservoir is being
processed into drinking water every
year in the Luisenthal plant located
directly below the reservoir.
From raw water to drinking water
Depending on the quality of the raw
water, various process steps have to
be carried out, explains Ms. Hövel, a
specialist engineer at Thüringer Fernwasserversorgung.
“As the water usually
only has a very small passage
through the ground before it reaches
the reservoirs, it is softer than
groundwater. The equilibrium pH value
of the raw water is often above the
permitted pH value of the Drinking
Water Regulation. In order to be able
to adjust this pH value at the end of
treatment and to increase miscibility
with other drinking waters, our raw
water is hardened at the beginning
of the treatment process.” The local
suppliers often add groundwater
from their own extraction to the district
water to produce a mixed water.
The water is also subjected to a final
disinfection process after filtration.
PROCESS TECHNOLOGY & COMPONENTS 2024
33