Some Chemical Aspects of the Ammonia‐Chlorine Treatment of Water

Chemical Properties of Chlorine Dioxide in Water Treatment

“…tone, which have a higher total residual value. This indicates that the free chlorine dioxide solutions have higher redox potentials than their compounds or mixtures, just as is true for chlorine (19).…”

Ortho‐tolidine Titration Procedure for Measuring Chlorine Residuals

“…At pH 7.0 ( Fig. 1 and 2), at which the process of free residual chlorination progresses very rapidly (4,9), and at pH 5.5 (Fig. 3, 4 and 7) at which it is appreciably slower, the OTT readings were zero until the chlorine to ammonia-nitrogen dosage ratio exceeded 6: 1.…”

“…The number of milliliters of standard orthotolidine solution required gives directly the parts per million of free available chlorine in the sample. 4. The results from a first titration of samples having residuals higher than I ppm.…”

“…Tap water from the Galveston, Tex.. city supply was used, which as drawn was at pH 7.8 and Additional laboratory experiments and actual application of the test in connection with free residual chlorination of many other types of water are needed before the full value and limitations of the ortho-tolidine titration procedure can be known. Comparison tests with the amperometric procedure (3,4) for free and combined chlorine would demonstrate more adequately just what the accuracy of ortho-tolidine titrations is for measuring free available chlorine in the presence of and ortho-tolidine-arsenite tests (OTA) for free and total chlorine were made after 5 minutes, 15 minutes, 1 hour and 2 hours of chlorine contact. The results of tests applied after 5 minutes, 1 hour and 2 hours are presented graphically in Fig.…”

Bactericidal Properties of Free and Combined Available Chlorine

“…added amounts of chlorine result in corresponding decreases of ortho-tolidine residual chlorine and ammonianitrogen, until, when about 9.0 ppm. has been added, the residual chlorine content and the ammonia-nitrogen content will be zero (3). Within this part of the curve the residual chlorine present is combined available chlorine.…”