The priority trace elements arsenic and selenium werePriority trace elenients such as arsenic, selenium, cadmium, chromium, copper, lead, silver, and zinc are often present in the discharges from coal-fired electric power plants. These elements may be eliminated from the waste streams by coprecipitation with amorphous iron oxyhydroxide. Iron oxyhydroxide is formed when a ferric salt (e.g., ferric chloride) is added to the waste.

Formulas for calculating six saturation indexes are derived. The indexes are expressed in terms of commonly measured characteristics of water quality. They are evaluated for their ability to determine whether a water is undersaturated, saturated, or oversaturated with respect to calcium carbonate (CaCO3) and to predict the water's capacity for CaCO3 deposition or dissolution. Important concepts that are often poorly understood are clarified.

Under extended low‐flow conditions, water can leach cementitious materials from cement–mortar lining, and significant increases in pH can result. Corrosion of cement–mortar lining—i.e., the leaching of lime from the cement matrix—can impair water quality by increasing pH, calcium, and alkalinity. Field tests at two utility sites evaluated the effects of water flow, lining method, seal coating, water quality, and cement–mortar composition. Water that remained stagnant in newly lined pipe sections for a relatively long time (one week) exhibited significant water quality effects—e.g., pH increases up to 12. Asphaltic seal coats significantly reduced cement–mortar corrosion in both tests. At one site, corrosion increased when the mortar contained Type II cement, a water‐reducing admixture, pozzolanic material, or a high proportion of sand. At the other site, none of these parameters significantly affected results. Design and operating measures to minimize stagnation can reduce corrosion effects.

This, Part 2, explains the relative ease by which one can calculate the various chemical parameters of a water and determine the most economical treatment via the use of C-L diagrams.

This is the first of three presentations conceived to im prove the operator's understanding of the process of pipe protection by calcium carbonate precipitation.