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  2. Chalk - Wikipedia

    en.wikipedia.org/wiki/Chalk

    Chalk is a soft, white, porous, sedimentary carbonate rock.It is a form of limestone composed of the mineral calcite and originally formed deep under the sea by the compression of microscopic plankton that had settled to the sea floor.

  3. Limescale - Wikipedia

    en.wikipedia.org/wiki/Limescale

    When heating hard water on the stove, these gas bubbles form on the surface of the pan prior to boiling. Gas exsolution can also occur when the confining pressure is released such as when you take the top off a beer bottle or where subsurface water is flowed into an atmospheric pressure tank.

  4. Lime softening - Wikipedia

    en.wikipedia.org/wiki/Lime_softening

    Lime softening (also known as lime buttering, lime-soda treatment, or Clark's process) [1] is a type of water treatment used for water softening, which uses the addition of limewater (calcium hydroxide) to remove hardness (deposits of calcium and magnesium salts) by precipitation.

  5. Hard water - Wikipedia

    en.wikipedia.org/wiki/Hard_water

    A bathtub faucet with built-up calcification from hard water in Southern Arizona. Hard water is water that has a high mineral content (in contrast with "soft water"). Hard water is formed when water percolates through deposits of limestone, chalk or gypsum, [1] which are largely made up of calcium and magnesium carbonates, bicarbonates and sulfates.

  6. Calcium carbonate - Wikipedia

    en.wikipedia.org/wiki/Calcium_carbonate

    Calcium carbonate reacts with water that is saturated with carbon dioxide to form the soluble calcium bicarbonate. CaCO 3 (s) + CO 2 (g) + H 2 O(l) → Ca(HCO 3) 2 (aq) This reaction is important in the erosion of carbonate rock, forming caverns, and leads to hard water in many regions. An unusual form of calcium carbonate is the hexahydrate ...

  7. Groups demand answers over river sewage leaks - AOL

    www.aol.com/news/groups-demand-answers-over...

    This means Andoversford is in the top 20 of Thames Water's 619 most polluted sewage treatment works. "[in the]13-14 years I've been here, it's changed beyond all recognition," Mr Chalk said.

  8. Water treatment - Wikipedia

    en.wikipedia.org/wiki/Water_treatment

    Dalecarlia Water Treatment Plant, Washington, D.C. Water treatment is any process that improves the quality of water to make it appropriate for a specific end-use. The end use may be drinking, industrial water supply, irrigation, river flow maintenance, water recreation or many other uses, including being safely returned to the environment.

  9. Chalk Group - Wikipedia

    en.wikipedia.org/wiki/Chalk_Group

    The Chalk Group is now divided into a White Chalk Subgroup and a Grey Chalk Subgroup, both of which are further subdivided into formations.These modern divisions replace numerous earlier divisions, references to which occur widely on geological maps and in other geological literature.