Chlorination for Algae Control

Abstract

The control of taste and odor has been one of the chief difficulties experienced in supplying a palatable water in Texas during 1926. Some 117 towns are using surface water for domestic purposes, and in a majority of cases an impounding reservoir or lake is used for storage purposes. These surface reservoirs occupy on an average an area of perhaps seventy acres, with an average depth of not more than ten feet. A great proportion of our surface water contains a large amount of bicarbonate alkalinity. This characteristic, together with the long periods of sunlight and fairly high temperatures, creates extremely favorable conditions for algae multiplication. The density of plankton life in these reservoirs is relatively high, due to the limited volume of water coming in from water sheds of small area, and the depth of penetration of the sunlight through the relatively clear waters. This is productive of heavy growths of plankton and subsequent production of objectionable tastes and odors. The surface waters of the state support a large number of the typical plankton forms, among which oscillaria, spyrogyra and navicula are the forms most commonly occurring from the three main algae divisions. The general preparatory training of the ordinary plant operator in Texas does not include microscopical work and usually the first indication that he may have of a large increase in the plankton life is an increased color in the water or complaints of taste and odor from the consumers. In such cases the usual copper sulphate remedy is applied, calculations being made from the standard dosage table as compiled by investigators some years ago. The treatment is applied either by dusting the crystal lightly over the water surface, by solution feed, or by dragging a sack of the chemical through the water at the end of a boat. Here, as in other states, this method has given satisfactory results where properly and sufficiently frequently applied. For large bodies of water the Texas State Board of Health has felt justified because of its experience, in continuing to recommend copper sulphate treatment.