Removal of Iron from Water Supply, Punta Gorda, Florida

Abstract

The water supply for the city of Punta Gorda is obtained from five 6-inch wells which are screened between depths of 60 and 90 feet, the water coming from a fine sand stratum between these two points. These wells were put down in 1925 to replace the old deep flowing wells which were heavy in sulphur and hardness, in an attempt to get softer water and water free from sulphur. The new wells yielded a very good quality of water for several months, but continued pumping brought about a continual increase of iron and magnesium content so that in 1929 the water contained 19.6 p.p.m. of iron and magnesium. The water became very objectionable, both as to taste and stains resulting from its high iron content. No attempt will be made in this paper to elaborate on the various objections to water with high iron content, since most of you are familiar with its damaging effects either from experience with your own water plants, or through observation of its effect in other plants. Punta Gorda was confronted with the necessity of doing something and of doing it at a time when its finances were very limited. It was not thought necessary at this time to attempt to soften the water, but simply to remove the iron and sulphur and, if possible, do this without the use of chemicals. Experiments to this end were carried on over a period of about eighteen months. It was then decided to use aeration in connection with an upward flow contact filter. This plant was built at a very small cost and has proven very satisfactory. With it we were able to reduce the iron content from 19.6 to 0.1