Repeated attempts have been made to develop a corrosion index that would be applicable to all waters. These attempts have made it clear that a series of indexes must be employed to take into account the many different types of corrosion as well as all mitigating parameters.

The basic objectives of this study were to gain a better understanding of the stoichiometry of the coagulation of organic color with ferric sulfate and to develop quantitative relationships that would permit the prediction and control of optimum coagulation conditions for efficient color removal. The primary objectives of this work were: to utilize the newer techniques of microelectrophoresis in a critical study of coagulation phenomena and stoichiometry as specifically applied to color removal with ferric sulfate; and, to determine whether microelectrophoresis could be applied as a practical method for determining optimum coagulation conditions in water treatment plants.

The performance of packed‐column and diffused aeration for removing trihalomethanes from drinking water was related to water source, water temperature, contaminant concentration, and other process variables. Data obtained from this study were compared with theoretical predictions and with the results of previous feasibility studies. Based on efficiency and cost, packed‐column aeration appears to be the more promising of the two technologies.

Although this article discusses radionuclides in general, its focus is on radium, uranium, and radon, which are the radionuclides of most concern to drinking water suppliers. Developed as the result of literature searches and interviews with personnel from the US Environmental Protection Agency and the California Department of Health Services, the article covers radionuclide chemistry, the occurrence of radionuclides, current and future regulations, treatment technologies, and monitoring.

Jar tests and a circulating water system were used to evaluate the effect of water quality parameters, in particular the Langelier index (SI), on the corrosion of galvanized steel. Since waters with a positive SI were sometimes found to be at least as corrosive as waters with a negative SI, especially if the effect of dissolved oxygen was neglected, no definite relationship could be established between corrosion rate and SI. In both Gainesville, Fla., tap water and deionized water, corrosion was observed to be fastest in the pH range 5-6.5. A general mechanism for the formation of corrosion products is presented. Overall results suggest that the SI should be used only with caution in the practice ofcorrosion control and that prediction of a water' s corrosivity should also consider the influence of other water quality parameters.Iron and steel pipes are usually coated on the corrosion of galvanized-iron with zinc to protect them from extensive structure+ have received considerable corrosion damage. Since the introduction attention. Investigations have been conof galvanized pipe, one of the oldest and ducted on the fundamentals of zinc cormost common plumbing materials used rosion, such as the electrochemical in drinking water systems, zinc has been behavior of zinc5 and the natural pitting reported in water supplies,' and studies of its crystals,6 as well as the effect of TABLE 1anions.4 However, little is known about the effect of some water quality factors on the corrosion of galvanized pipe in potable water systems, including the nature of the corrosion products formed. Further understanding of the corrosive reaction of water on galvanized pipe is needed to help water treatment plant operators produce a less corrosive treated water. For instance, because the US Environmental Protection Agency (USEPA) has implicitly recommended the use of the Langelier index (calcium carbonate [CaCOs] saturation index) by utilities to monitor the corrosive potential of process water, the effect of the Langelier index on the corrosion of zinc in galvanized pipe should be thoroughly evaluated.