ELIMINATION OF IRON

Southland Times, Issue 23773, 22 March 1939, Page 6

ELIMINATION OF IRON

FUNCTIONS OF NEW PLANT FOREIGN MATTER CAUGHT IN FILTERS A statement on the progress of the installation and operation of the plant was made by the Mayor (Mr J. R. Hanan} at last night’s meeting of the City Council.

“Many citizens seem to be under a misapprehension as to the position of the water treatment plant,” Mr Hanan said, “and it may be of interest to state the position as it now exists.

“There are two plants —one at the power house and one at the water works. It has been said that the water in Invercargill of recent times has been much worse than it was in years gone by. In the past, we have relied on aeration in reservoirs to allow impurities to settle before distributing the water for domestic consumption, but as the city progressed, these reservoirs became inadequate.

“When the water is pumped from the wells to the surface, it is of a beautiful crystal-clear quality, but on contact with the air, certain soluble things are precipitated by oxidation. Among these, iron is the most obvious, and during recent years this iron has been deposited in the water mains, as the housewife knows full well in the Monday morning wash. The idea of a water treatment plant is to remove the impurities before the water is pumped through the mains. This is done by a system of filtration. The water from the wells is passed through the filters which contain sand and gravel of various grades, and a substance known as polarite, which has the effect of changing the soluble matter in the water into insoluble matter, which is caught in the layers of sand and gravel. IRON CONTENT “The iron content is in the form of ferrous bicarbonate (which is soluble) when it is pumped out of the wells. After contact with the air it is oxidized and appears as the insoluble iron oxide. The polarite acts as a catalytic agent to assist in the removal of this oxide.” The Mayor added that the plant at the power house was almost complete and considerable quantities of impurities were being removed daily. When one saw the quantity that was being removed, one could well credit what an inestimable boon the installation was going to be to the people. The chlorinating apparatus was yet to be installed, and this would add greatly to the efficiency of this plant. Therefore, it was not correct to say that the plant at the power house was in full operation, but he had heard very satisfactory reports that an improvement had taken place in the quality of the water in Northend. The larger plant at the water works would probably not be in operation until May, and until then, the effect on the city as a whole, would not be noted. WATER NOT INJURIOUS “Let it be clearly understood,” he concluded, “that although for some years letters to the council and to the newspapers have evinced widespread dissatisfaction with the quality of our water supply, that this water is, from a health point of view, by no means injurious. The Government analyst’s reports have shown that for human consumption there is nothing wrong with the Invercargill water supply, but although this is true, it is a small consolation to the housewife who has a lot to put up with, but the citizens can rest assured from the indications of the amazing success of the powerhouse plant, while only partly operating, that the difficulties of the housewife will soon be obviated. During the years there has been a considerable accumulation of deposit in the mains throughout the city, and when the plants are in operation, a considerable flushing of the mains will be undertaken, which may cause some temporary inconvenience, but as the water which will be pumped into the mains will be absolutely pure, it will only be a matter of little time before everyone will be satisfied.”