Calcium water quality indicator

WA water quality labs by atomic absorption and autoanalyzer techniques. Charge balance calculations Indicated that all dissolved species of significance were analyzed. Comparison of filtered and unflltered aliquots suggested that un-lonlzed species were not present In appreciable quantities. Sampling and analysis uncertainties were determined by the operation of two co-located samplers for 16 weeks. The calcium and sulfate data were corrected for the Influence of sea salt to aid In the separation of the factors. This correction was calculated from bulk sea water composition and the chloride concentration In rainwater (11). Non seasalt sulfate and calcium are termed "excess" and flagged by a ... 

Exercise 6.12 A well was terminated at a depth of 250 m in sedimentary rocks. The water abstracted had poor taste and was found to contain 450 mg S04/1, balanced mainly by calcium. What does the composition indicate What can be done to improve the water quality ... 

The field studies indicated that all of the dechlorination chemicals were effective in neutralizing free and combined chlorine to below 0.1 mg/L. In most cases the stoichiometric amount of dechlorination chemicals removed more than 90% of the chlorine. However, the reaction rates and the water quality impacts varied with the type, amount, and form of the chemicals used. In general, the rates of dechlorination using sodium/calcium thiosulfate were slower than those using the other chemicals. However, studies by others indicated that dechlorination of wastewater samples using sodium thiosulfate was more rapid that using ascorbic acid (24). 

The solubility of elements in freshwater is limited and the solubility of calcium and magnesium carbonates are of particular importance in freshwaters. The solubility of carbonates is inversely proportional to the temperature of the water. In other words, as the water temperature increases, calcium and magnesium carbonates become less soluble. If the solubility decreases sufficiently, carbonates will precipitate and form a scale on the surfaces of the system. This scale can provide a protective barrier to prevent corrosion of the metallic elements in a system. Excessive scale deposits can interfere with water flow and heat transfer. The quality of the scale is dependent on the quantity of calcium that can precipitate as well as water flow and the chloride and sulfate content of the water. The tendency of water to precipitate a carbonate scale is estimated from corrosion indices such as the Langelier Saturation Index (LSI) and Caldwell-Lawrence calculations [6-8] which use calcium, alkalinity, total dissolved solids, temperature and pH properties of the water. Other indices, such as the Ryznar Index... 

Concentration measurements of aqueous solutions of salt, sugar, antifreeze etc. Quality control of a number of industrial processes requires checking the concentration stability of different solutions and water soluble fluids. The off-line use of Abbe refractometers is sometimes an obstacle to real-time process control. Several researchers have tested different types of LPGs for the measurement of concentrations of aqueous solutions of sugar, salts, and antifreeze. Falciai et al. [16] used a UV written LPG (X = 1,530 nm, A - 400 pm) to measure concentrations of aqueous solutions of sodium chloride (NaCl) and calcium chloride (CaCl2) having refractive indices in the 1.32-1.42 range. In a later paper, Falciai et al. [17] also measured... 

The system associates a quality variable q x with each parameter, x, of the analysis. Each quality variable is assigned an initial value of zero. When there is evidence to support or contradict the reliability of the parameter value, the quality variable is incremented or decremented. Consider the calcium concentration in an analysis. Initially its quality variable, q calcium, is set to zero. Assume that the carbonate species concentrations have been shown to be reliable but that the geochemical model shows calcite to be oversaturated by several tenths of a unit. The sample is of a limestone ground water, and so should be calcite saturated. Assuming that the program and thermochemical data used are correct, the calcite oversaturation can be interpreted as indicating an erroneous calcium analysis. q calcium is therefore decremented because of this evidence that the calcium value is incorrect. The overall quality... 

Hardness-dependent parameter. All criteria are as indicated at hardness less than or equal to 50 mg/L, as calcium carbonate. If hardness exceeds 50 mg/L, as calcium carbonate, then criteria is equal to result of hardness based equations as found in quality criteria for water, c exp (0.8473 [In (hardness as mg/L)] + 0.8604). ig/L exp(0.8473[In(hardness as mg/L] + 0.7614)ng/L " Total recoverable... 

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