SOPHISTICATED INDICES AND OLD STANDARDS SOPHISTICATED INDICES AND OLD STANDARDS WatSim™ combines the predictive methods for copper and lead outlined in E.P.A. Drinking Water Research Division technical papers and publications with the prediction accuracy of "ion association models" to provide sophisticated water quality simulation. Parameters modelled include lead and copper levels, the scale potential of common scale forming species, and the prediction of corrosion rates. WatSim provides a valuable adjunct to field research evaluations and may be accepted as computer simulation in lieu of such field studies.
Common treatment approaches such as pH control, phosphate addition, and D.I.C. adjustment can be evaluated using WatSim. The computer modelling of water chemistry provides an evaluation of the impact of such treatments and adjustments upon scale potential, corrosion rate, and lead and copper levels.
WatSim brings main frame calculation power for water treatment to the level of the PC, eliminating (or at least greatly minimizing) the need for simplification and sometimes misleading assumptions.
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The old standards provide insight into scale potential for single scales. They are limited to simple estimation methods, and do not take into account phenomena such as "Common Ion Effects." Sophisticated indices such as ion association model saturation levels account for these effects and can be calculated for most foulants. Ion association model indices also provide a more realistic view of scale potential than the old standbys. They base their calculations upon free ion concentrations rather than the total analytical values used for most indices. In natural waters, calcium (for example) is not typically found as 100% free calcium. A portion of the calcium may be bound to sulfate, another portion of the total may be tied up by bicarbonate, hydroxide or other species with which it associates. Ions in water are typically associated with other ions. Indices calculated based upon total ion present (e.g. total analytical calcium) can be misleading. In high TDS waters, they can grossly over estimate the driving force for scale formation and growth. The ion association model indices overcome this shortcoming by estimating the concentration of free ions, and calculating indices using the free concentration rather than the total. Ion association model indices improve the realism, and the accuracy, of scale prediction in this manner.
WatSim uses an ion association model to extend the applicable ionic strength for calculations, and to provide consistent, reproducible indices for common, and not so common, scale forming species, and for predicting the solubility of heavy metals such as lead and copper.
Old Standards |
Langelier Saturation Index |
Ryznar Stability Index |
Practical (Puckorius) Scale Index |
Larson-Skold Corrosivity Index |
Calcium Carbonate Precipitation Potential (C.C.P.P.) |
| Maximum Solubilities Calculated By WatSim | |
| Copper Solubility | includes free ion, carbonate, bicarbonate and hydroxides |
| Lead Solubility | includes free ion, carbonate, bicarbonate and hydroxides |
| Calcite | CaCO3 |
| Aragonite | CaCO3 |
| Gypsum | CaSO4.2H2O |
| Anhydrite | CaSO4 |
| Amorphous Silica | SiO2 |
| Magnesium silicate | MgSiO3 |
| Hydroxylapatite | Ca5(PO4)3(OH) |
| Tricalcium phosphate | Ca3(PO4)2 |
| Brucite | Mg(OH)2 |
| Fluorite | CaF2 |
| Strengite | Fe(PO4)2 |
| Siderite | FeCO3 |
| Amorphous Ferric hydroxide | Fe(OH)3 |
| ACIDS | ALKALIS |
| 66o Be Sulfuric acid | Lime |
| 35% Hydrochloric acid | Soda ash |
| Nitric acid | Sodium bicarbonate |
| Carbon dioxide | Caustic soda |
| Caustic potash |
| Operating System | Windows 3.1, 3.11, NT 3.51, NT 4.0, 95 |
| CPU | 486 DX2-66 or better, Pentium 100 recommended |
| Math coprocessor | Required for all versions due to heavy number crunching |
| Memory (RAM) | 8 megabytes Windows™ 3.1, 16 megabytes Windows 95, 32 megabytes Windows NT |
| Hard Drive Storage | All WatSim versions require two (2) to four (4) megabytes of hard drive storage, depending upon version, options, and number of systems evaluated. |
| Video | Super VGA resolution recommended (800x600 or 1024x768), VGA resolution minimum (640x480) |
WatSim
The basic WatSim program calculates all scale indices, Pb and Cu maximum
solubility, saturation levels, momentary excess, and distribution of ions. Input can be in
any standard analytical units varying from mg/L as the ion to oFr, oGer,
mg/L as CaCO3, or epm. A single button allows the selection of analytical units
favored by the major Water Treatment Service Companies.
Various methods for pH prediction are included, including the development of an empirical curve for a specific water.
Acid or alkali requirements can be calculated at a Target pH, Target Calcite Saturation Level, Target D.I.C., or at a Target Index (e.g. Langelier, Ryznar).
Output is presented in tables, two dimensional (2D), three dimensional (3D), and four dimensional (4D) color coded graphics. Tables include:
| Source Water Analysis | Water Chemistry versus Temperature |
| Source Water Deposition Potential Indicators | Deposition Potential Indicators versus Temperature |
| Water Chemistry versus pH | Water Chemistry at Target pH, Temperature, Index, or D.I.C. |
| Deposition Potential Indicators versus pH | Deposition Potential Indicators at Target pH, Temperature, Index, or D.I.C. |
| Indices versus pH | Maximum Pb Solubility versus pH |
| Indices versus Temperature | Maximum Pb Solubility versus Temperature |
| Indices versus pH and Temperature | Maximum Pb Solubility vs pH and Temperature |
| Saturation Levels versus pH | Maximum Cu Solubility versus pH |
| Saturation Levels versus Temperature | Maximum Cu Solubility versus Temperature |
| Saturation Levels versus pH and Temperature | Maximum Cu Solubility vs pH and Temperature |
| Momentary Excess versus pH | Inhibitor Level Required versus pH |
| Momentary Excess versus Temperature | Inhibitor Level Required versus Temperature |
| Momentary Excess versus pH and Temperature | Inhibitor Level versus pH and Temperature |
| Note: three dimensional and four dimensional graphs are presented as Bar or Contours Plots. Graphs can be exported as .PCX, .BMP, and .TIF formats in the Windows versions. Graphs and Tables can also be "Cut & Paste" for easy transfer to Report, Proposal and Presentation generating programs. | |
WatSim Field Engineer Edition
The Field Engineer Edition performs all of the functions and has all of the features of the basic WatSim program. It adds the ability to select a water treatment product and obtain dosage recommendations. Each table has an additional line for Dosage and Predicted Corrosion Rate. An additional graph selection appears for all two (2D), three (3D) - the Dosage Profile.
The Field Engineer edition can load a Product File (.PRD) for use in determining treatment rates and developing dosage profiles. But, alas, the Field Engineer Edition lacks the ability to edit or create Product Files, or even look at the ingredients. They must be created (and edited) using a higher member of the WatSim Series. Both the Formulator and Laboratory Editions can create and edit Product Files.
WatSim Formulator Edition
The Formulator Edition adds the ability to create and edit product files. Creating a Product File is as simple as filling in a computerized formula (batch) sheet. Product Files can be password protected to maintain confidentiality. Files so created can be used by the Formulator Edition or copied to the \MUNI\INHIB sub-directory on other computers with WatSim Rx programs.
Formulator Editions are used extensively by water treatment companies who wish to use the inhibitor models supplied by French Creek, by Systems Chemists who wish to evaluate and compare the treatment programs proposed for their cooling systems, and by consultants for performing in-depth technical and economic analyses of aqueous systems.
WatSim Laboratory Edition
The Laboratory Edition adds the ability to develop scale inhibitor, corrosion inhibitor, and corrosion rate predictive models from laboratory data, field data, or a combination of both. Dosages (or Rates) can be modeled as a function of any parameters input into the program in their raw form, calculated indices, and other parameters calculated by the program.
Transforms are available and can be applied independently to each variable. For example, a CaCO3 inhibitor might be modeled:
This is, in fact, a common model for scale inhibitors.
A simple corrosion rate model might be correlated as follows:
A predictive model for lead or copper solubility might be modelled:
Inhibitor models developed by the Laboratory Edition are output to the .INH files used to develop Product Files. Raw data is stored in .COR files. Statistics are, of course, provided on each variable as you develop a model.
Laboratory Editions are used extensively by scale inhibitor synthesizers, and by major water treatment companies and by laboratories doing inhibitor and/or corrosion research.
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