THE DECOLORIZATION OF THE LITTLE RIVER WATER SUPPLY IN CONNECTION WITH FILTRATION AT SPRINGFIELD, MASS

Abstract

Sulphate of alumina as a coagulant and decolorizer is in use on many waters in the United States, and is recognized as one of the most effectual means of reducing an objectionable color in the water prior to filtration. The river water as applied to the West Parish filters of the Springfield water supply is naturally a water of few objectionable features. No large population is resident upon the water-shed and the sanitary conditions are excellent so that there is not a large danger of serious contamination of the supply at any time. By filtration a water free from practically all objections is produced, except that at times, the remaining color is noticeable, and the present systeni of coagulation is the result of a study of the means of correcting this one objection to the water. This water was first used as a supply in December, 1909, and sulphate of alumina was used for the reduction of color in the manner in which it is usually applied. The accompanying cut showing the use of coagulant during 1910 illustrates the amount of sulphate of alumina which was necessary for this reduction. Its application during this year was in accordance with the usual practice, that is, in amounts sufficient to secure a clear-cut reaction and the coagulant was applied continuously. The present method is illustrated by the chart showing the amounts and the color of the raw and filtered water during 1912 and 1913. As at present practised, excellent color reduction is secured by the use of 0.2 grain of sulphate of alumina per gallon of water during a larger portion of the time.