INTRODUCTION

The history of treating potable water with phosphates dates back to the early 19th century, and is more and more commonly applied, as the water becomes more and more rare, and its quality decreases due to a high rate of recycling. The drinking water supply is done from a great number of small and large size water works as well as by the private users themselves. Hydrological ground formations and pollution determine the quality of water. In some cases the use of surface water cannot be avoided, but in many cases suitable wells with an appropriate water quality are available. Of course, theoretically it is possible to add some naturally occurring ingredients to the water or remove some ingredients to bring the water to a suitable level of balance, but this is not only high in cost, but also requires a thorough analysis and different approach in all cases. Phosphates are the only natural ingredients in the water showing a positive improvement of the water in almost all cases of problems due to corrosion and scale. Adding phosphates to the water has a long history and will definitely also have a future.

Adding phosphates to the water is technically not so simple. Usually phosphates have to be dissolved to make so-called stock solutions, which then are dosed with proportional dosing pumps to the water. Problems using this method are numerous, e.g. bacteria growth in the stock solution, inappropriately prepared stock solution with lumps inside, incorrectly operating dosing pumps, and very often dosing pumps which are broken and cannot be repaired due to the inavailability of spare parts.

SILIPHOS SYSTEM

SILIPHOS is a so-called calcium polyphosphate, containing a well balanced mixture of up to 20 different inorganic phosphates and sodium silicates.

Siliphos product types:

• Silphos - glassy spheres pieces with a diameter of about 2 cm
• Siliphos II - glassy spheres pieces with a diameter of about 2 cm and glassy granulated shiver with an average grit size of 2-4 mm.

Siliphos II has a higher rate of solubility compared to Siliphos.

Siliphos and Siliphos II are slowly soluble and will be fed into water by a dispenser.

The dosing rate should be between 2 - 5 ppm P₂O₅ equivalent to 3 - 8 ppm Siliphos.