The marked success which the ammonia-chlorine treatment has met during the past two years throughout the United States in the prevention of tastes and odors commonly associated with the chlorination of water supplies, coupled with the simplicity and the low operating and first costs of the process, has made it expedient for Chicago to give the treatment careful consideration.It was apparent from the beginning that, in giving consideration to the use of the ammonia-chlorine treatment, it would be necessary to determine carefully what the bactericidal velocity of the treatment was as compared with that obtained in ordinary chlorination practice. A slowing up of the bactericidal action would be of great disadvantage if the treatment were to be applied at the Chicago pumping stations, because of the lack of protection it would afford to nearby consumers, many of whom receive their water in less than three minutes after it is chlorinated. If such delayed action actually occurred, and it was considered advisable to use the treatment, it would be necessary to provide sufficient detention period to obtain the required bactericidal effect before the water was pumped into the system.The literature on this subject was not conclusive; some observers noticed a decided lag in bactericidal velocity, while others observed none. The investigations made by Holwerda" and more recently by Baker and Schmelkes" indicate that the widely varying effects observed were probably due to the application of the treatment to waters of different hydrogen-ion concentrations.

The Chicago Department of Water and Sewers has been requested to develop recommendations for desirable quality criteria goals for various parameters for Lake Michigan water received at its intakes. This article describes Lake Michigan water as an excellent source of water supply that is easily treated in conventional rapid sand treatment plants to produce a superior quality water for domestic and industrial use. It is only during periods when industrial and sewage pollution of the water is present that it becomes difficult to produce the customary high quality water. Furthermore, increased nutrients in the water definitely help bring about biologic degradation of the lake. The article discusses recommendations by the department for achieving the maximum goals in various parameters of quality. The parameter threshold odor number has been omitted because of differences in the effectiveness of treatment. It is therefore suggested that natural algae odors be omitted from these parameters and that a maximum goal of a threshold odor number of 6 be set for the intake water for odors produced by industrial waste pollution.

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