In the case of "Permutit " " B," the plant is designed to operate for periods varying from four hours at a time to any longer period which may best suit works conditions, and is then fully exhausted. The material, however, is susceptible of extremely rapid regeneration, and a large industrial unit can be completely regenerated and re-commissioned in a period of one hour or less. The plant is, therefore, rapidly regenerated at the conclusion of each softening period, and one unit is capable of operation both day and night in this manner.

Great Saving Of Salt

An important advantage attending the employment of "Permutit " " B" is that a reduced salt consumption in regeneration is rendered possible, as compared with the older material; in addition to which there are several other features of the new material which are of the utmost practical value to the industrial user. For example, "Permutit " "B " is of hardier physical character, and therefore, less susceptible to loss through wear and tear of ordinary usage, while absolutely unaffected by carbonic acid in the water.

No Solid Residue

The calcium and magnesium chlorides formed as a result of the treatment of exhausted "Permutit " with common salt in the regeneration process, are soluble in water and leave the plant in the form of a clear solution, thus rendering unnecessary any arrangements for the disposal of solid sludge. The effluent from " Permutit " softeners can be sent into the ordinary drains and is entirely innocuous.

The Chemical Exchange

The exchange action may be represented chemically by the following equations, in which the contraction " Pm " represents " Permutit " :-

1. For the softening of " temporary " hardness (the hardness due to the Carbonates of Lime and Magnesia).

Removal of Carbonate of Lime by " Permutit."

Na2- Pm + CaH2 (CO3)2 = Ca - Pm + 2 NaH CO3

Sodium ;Calcium ; Calcium Sodium

Permutit Bicarbonate Permutit Bicarbonate

Removal of Carbonate of Magnesia by " Permutit."

Na2- Pm + Mg H2(CCO3)2 = Mg- Pm +2 Na H CO3 Sodium ;Magnesium = Magnesium , Sodium

Permutit ' Bicarbonate = Permutit Bicarbonate

11. For the softening of " permanent " hardness (the hardness due to the Sulphates, Nitrates, Chlorides, etc., of Lime and Magnesia).

Removal of Calcium Sulphate by "Permutit."

Na2 - Pm + CaSO4 = Ca - Pm + Na2SO4 Sodium ;Calcium ;Calcium Sodium

Permutit ' Sulphate = Permutit Sulphate

Removal of Magnesium Chlroide by " Permutit."

Na2 - Pm + Mg CI2 = Mg - Pm +2 Na CI Sodium ;Magnesium Magnesium Sodium

Permutit + Chloride = Permutit + Chloride

It will be evident that after this exchange has proceeded for a specified time, all the exchangeable sodium in the " Permutit" will have been replaced by calcium and magnesium from the treated water. At this point the softening capacity of the " Permutit" bed is exhausted, but it is not necessary to re-charge the filters with fresh " Permutit."