English subtitles for clip: File:Wie aus Flusswasser Trinkwasser wird.webm

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Bernd Heinz from the Hengsen waterworks
explains the work steps,

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how drinking water is obtained from the
river Ruhr is turned into drinking water.

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This process takes three to four days.

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BH: First we take water from the Ruhr,

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then channel this water
into the corresponding reservoirs

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or pre-sedimentation basins,
where the water comes to rest,

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and the first large suspended particles
can settle at rest.

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Narrator: In Hengsen, a small reservoir
serves as a sedimentation basin.

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In the overflow to the gravel pre-filter basin

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there are cascades
to enrich the water with oxygen.

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This supports microbiological
cleaning processes in the gravel filter.

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From there, the Ruhr water
is fed into the next filter basin.

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Because after sedimentation and gravel pre-filtering
further purification measures are necessary.

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In the next step, the water flows
through slow sand filters.

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In the fine-grained soil layers
all coarser components remain trapped.

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Biologically–physically, the water
is now in a pre-purified state.

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It seeps through the soil into the groundwater

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and is pumped out of the ground
again by deep wells.

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BH: The near-natural process,
that we have today,

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basically takes out a lot of the classic
substances that we have.

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However, the procedure is not sufficient
to take out

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drug or industry-chemicals residues.

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For this, activated carbon is key term.

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This is the core stage of our extended
water treatment that we are investing in.

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Activated carbon has a big effect –
such small amounts of activated carbon,

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here it is four grams, have the
surface area of about a soccer field,

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so have a very large area, so that
trace substances that are in the water,

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can accumulate there and
are bound by the activated carbon

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and are therefore no longer
contained in the drinking water.

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That is the core measure,
that we have.

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N: After this pre-treatment,
the filtered groundwater

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further technical processes,

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to meet the high requirements for the purity
of the drinking water.

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It is deacidified and an additional
UV light disinfection ensures

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that on its way from the waterworks

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to the consumer it remains
bacteriologically flawless.