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Lime Dosing

There are several ways to raise the pH of surface waters.  These include the addition of lime, soda ash and caustic soda. Due the environmental harm associated with sodium, the choice of chemical is limited to lime. There are numerous methods to dose lime.   These include;
  1. Dry lime feederThe dry lime feeder is an Archimedes screw arrangement designed to discharge small quantities of dry lime to a water tank.  Dry lime is fed into a hopper arrangement above the Archimedean screw. Because lime settles quickly, the dry lime has to be discharged into a suitable mixing basin.The lime feeder is easily controlled and delivers exact amounts of lime.  The major detractor, in our opinion is the tendency of lime to stick to the feed hopper walls when the lime is slightly moist.  Also the feed hopper is quite small, meaning that lime might have to be added twice a day or more.
  2. Rotostab The Rotostab unit comprises a lime solution tank and mixing basin.  The Rotostab is designed for ease of use and maximum efficiency.  The Rotostab unit uses a small amount of feed water to drive the lime solution to the mixing basin.We highly recommend this unit because of the ease of use and general low maintenance requirements.
  3. In line dosingThe difficulty with in line dosing of lime is that the dose pump continually blocks.  The way to minimise blockages would be to dose a very dilute lime solution.  This in turn means that an operator would have to continuously add small amounts of lime to the solution tank.