BROMINE CHLORINE
SLIDE RULE NOW AVAILABLE

Estimating the bromine feed rate to replace chlorine has been by trial and error and rule of thumb for years. The Bromine Chlorine Slide rule from French Creek provides a modeling tool to predict the bromine feed required to match the killing power of current chlorination practice.

Input current chlorine feed rates, residuals, and chemistry parameters such as pH and ammonia into the Bromine Chlorine Slide rule and output projected bromine and chlorine usage and costs versus pH. Both tables and graphs are available.

frenchcreeksoftware.com

Plot Current and Projected Costs versus pH to find the pH where bromine is economically more attractive than chlorination.

The initial version of the Slide rule works with chlorine gas, 10%, 12%, and 15% NaOCl, and 45% NaBr. Stabilized chlorine and bromine sources will be added to future releases.

Visit our web site at http://www.frenchcreeksoftware.com to download a fully functional demo. Special introductory pricing applies until December 31, 1997.

hyd-RO-sat and hyd-RO-dose Provide Ion Association Model Indices and Dosage Modeling For R.O. Systems

Reverse osmosis brine modeling has been a popular "un-intended" application of WaterCycle® since the program series release in 1990. hyd-RO-sat and hyd-RO-dose legitimize the application with a program series developed specifically for the needs of R.O. chemists and engineers.

hyd-RO-sat and the hyd-RO-dose series use the French Creek high TDS ion association model engine and expand the ions modeled to include strontium and barium compounds.

pH control with common acids and alkalis is included. Feed rates to the raw water can be calculated to control feed water pH at a specific target, or to control brine pH.

"What-if" profiles include 2D plots of scale potential, acid-alkali feed, and inhibitor dosages versus % Recovery or pH. 3D plot profile versus both pH and Recovery.

The basic hyd-RO-sat program models scale potential and acid-alkali feed. The hyd-RO-dose series adds inhibitor modeling capabilities in the Field Engineer and Formulator Editions.

hyd-RO-sat and the hyd-RO-dose series were developed for use under Microsoft Windows. Visit our web site for further information and a fully functional run limited, date limited demonstration version. Special introductory pricing applies until December 31, 1997.

FRENCH CREEK ONLINE
http://www.frenchcreeksoftware.com

Need an update Fast? Or maybe a driver?
Online updates are available for registered users with annual maintenance agreements in the ONLINE UPDATE area.

Looking for Water Treatment Reference Articles?
Papers presented and/or published by French Creek are available for browsing in the ONLINE LIBRARY.

Have A Chemistry Question? Or maybe an answer?
The French Creek DISCUSSION GROUP provides a forum to ask other French Creek Software users questions and exchange information.

Need to Report A Bug?
Tech Support forms are available for submission.

Ready to Bite the Bullet?
Demonstration versions of French Creek Products are available for download. Some can even be paid for online.

Visit the French Creek Software web site today!

MODELING THE BIOCIDAL EFFICACY
OF BROMINATION vs CHLORINATION

There are many rules of thumb for converting from a biocontrol program based upon chlorination to a bromine based program. This article discusses the chemistry of these biocides and describes a framework for comparing their killing power. The method described is useful for predicting the cost impact of switching from chlorination to bromination, as well as in predicting the impact of increasing the control pH for a cooling system. The method also provides realistic feed rate starting points for bromination programs.

Basic Chemistry

The chemistry for chlorination and bromination has been well described in the literature and is commonly expressed in terms of the pH dependent equilibria:

HOCl <--> OCl^- + H⁺

HOBr <--> OBr^-- + H⁺

In the presence of ammonia, the halogens react to form bromamine and chloramines. The exact form of bromamine or chloramine formed is dependent upon factors such as pH, the halogen to ammonia ratio, and whether or not only a single halogen (HOBr or HOCl) or both (HOBr and HOCl) are present.

These halogens also react to form halamine derivatives of organics with amine group(s).

Hypochlorous acid (HOCl) is usually the primary "active" biocidal agent associated with chlorination. Hypochlorite (OCl^-) is considered to have an efficacy or killing power almost an order of magnitude less than HOCl. Chloramines are considered to have an even lower toxicity.

Bromine efficacy is somewhat different. Hypochlorous acid (HOBr) is still the primary "active" biocidal agent. Hypobromite (OBr^-) is not considered a poor biocide like its chlorine analog. Hypobromite is considered to have an efficacy or killing power equal to, or almost equivalent to, HOBr.

Bromamines also tend to have excellent biocidal activity, possibly due to the free avaialability of the bromine associated with them. Bromamines are considered to have a biocidal efficacy almost the same as hypobromous acid. Bromamine tend to be unstable and freely release bromine.

Bromchloramine is formed in the presence of oxidzing bromine and chlorine species. This halamine releases its oxidizing halogens much more readily than chloramines. This phenomena is probably responsible for the observation that bromination at 2 to 1 and 3 to 1 molar NaBr to Cl₂ ratios is almost as effective in the presence of ammonia as bromination at a 1 to 1 ratio. The predominant species expected in cooling water would be monochloramine for straight chlorination, monobromamine for a 1 to 1 ratio system, bromchloramine for a 2 to 1 ratio, or a mixture of monochloramine and bromchloramine for a 3 to 1 ratio. Other species might form at high halogen to ammonia ratios.

In order to model and compare the efficacy of bromination and chlorination, the relative efficacy or the halogen species must be established. The French Creek Software Br Cl Slide rule assigns HOCl a relative efficacy of 1.0 . The efficacy of other halogen species is compared to this "standard." Table 1 compares the default efficacies assigned by the program. All species are expressed as Cl₂.

Efficacies can be changed by the user. Many users, for example will want to increase the efficacy of chloramine in very long contact time systems.

Modeling Biocontrol Efficacy

The first step is to calculate the distribution of halogen species for the current chlorination practice. The dissociation constant for HOCl is used to distribute the Free Available Chlorine present.

[H⁺] [OCl^-]

K_HOCl = ^{_______________}

[HOCl]

The species are then expressed as Cl₂. The efficacy can then be calculated as equivalent HOCl killing power using the Efficacy Coefficients from Table 1.

Efficacy = Eff_HOCl [HOCl] + Eff_OCl^- [OCl^-]

When ammonia is present, the monochloramine should be calculated from the combined chlorine (T.R.C. - F.A.C.) or from the ammonia present, and its efficacy included in the total.

Efficacy = Eff_HOCl [HOCl] + Eff_OCl^- [OCl^-] + Eff_NH2Cl [NH2Cl]

This is the target efficacy used to estimate the oxidizing biocide requirement for equivalent killing power as pH changes, and for other oxidizing biocides.

The calculations become quite complex and beyond the scope of this article when ammonia is present. Breakpoints must be calculated for the various species possible and their efficacies/demand included in the calculations.

Regeneration

The regeneration of bromide to hypobromous acid by free chlorine has been observed. This would account for the improved efficacy observed with 2 to 1 and 3 to 1 or higher molar ratio biocontrol programs. Regeneretion assumes that chlorine is not involved in the actual biocide process. Hypobromous acid is reduced to Br^- as it is consumed as a biocide. Regeneration occurs when the bromide ion is re-oxidized to HOBr^-. Under these conditions, all free halogen species can be treated as if they followed the dissociation profile of hypobromous acid. The efficacies of hypobromous acid and hypochlorite can be also be applied to the total Free Available Chlorine.

A comparison of bromine requirements with and without regeneration provide insight into the "best case" (with regeneration) and "worst case" scenarios" (without regeneration. The French Creek Software Bromine Chlorine Slide rule allows this comparison to be made. Profiles can be run with regeneration, and without bromide regeneration.

Dear Cagliastro,

I'm at a loss. WaterCycle stopped working when I purchased and installed a new bi-directional printer. On program startup the message "Security Key Not Found" is printed, and then I'm kicked out. Reports are piling up!

Spellbound

Dear Spellbound,

Some of the new printers take over the parallel ports and refuse to let WaterCycle, DownHole SAT, or other security key protected programs, communicate with the dongle. Several solutions are available.

1) An immediate fix is to deactivate the "exclusive port" feature in the printer driver setup program.

2) Security key drivers can be easily installed and will fix the problem in many (but not all) cases. An easy to run Security Key Driver Setup program can be downloaded at the French Creek Web Site - http://www.frenchcreeksoftware.com .

3) You can install a second parallel port.

Hope these fixes get you up and moving.

C

Dear Cagliastro,

I just installed the Windows Version update. The program gives me an error "Error 901 - Files Critical To WaterCycle are missing. Contact Technical support." What happened? How do I fix it?

Lost

Dear Lost,

Two problems have been encountered that cause the message you received.

1) The Windows version MUST be installed in the \WATER directory for WaterCycle, the \DHSAT directory for DownHole SAT, and the \HYDRO directory for hyd-RO-sat.

Check your installation and make sure that you didn't force the program to a different destination (e.g. MYPROGS\WATER won't work). Re-install to the appropriate directory.

2) In Windows 95, the property sheet must have the correct directory specified as the working directory. Edit the shortcut to include the correct directory.

The same problem can be encountered in older Windows 3.1 installations. Click on the icon, and edit the properties to the appropriate default/working directory.

This should help Windows find the files.

C

Dear C,

The WaterCycle printouts include too much information for my customers. I would like to bring the printouts into Microsoft Word, and edit them. Can this be done?

Dying to Delete

Dear Deleter,

The Windows versions of our programs have the COPY option in the OPTIONS menu of printout windows. You can COPY just the active window printout, or COPY ALL active printouts. They can then be pasted into Word, or other word processing programs.

A few hints will keep your printout tables in line. Select a fixed width font such as COURIER or COURIER NEW before you PASTE the printout.

Make sure that the margins are narrow enough to hold the full line.

I've found that 10 point with 0.55" and 0.5" margins works well.

DOS version program users can select the print to file option. Import the .PRN file into your word processor as an ascii text file.

C

Dear Cagliastro,

Graph printouts are sometimes the size of a postage stamp on my HP printer. Can this bug be worked around?

Downsized

Dear Downsized,

This phenomena is rarely encountered, but can ruin your day. There is a built in solution in all of the French Creek water chemistry programs.

Go to the PREFERENCES menu.
Select PRINT MODE
Choose INDIRECT

This will return your 3D graphs to their intended size.

Another option is to COPY and PASTE the graphs into the software you are using to prepare reports (e.g. Microsoft Word, Corel Wordperfect, etc). Size them and position them where you desire.

A third option is to export them as graphic image files (.BMP, .TIF, .PCX). Import them into the report packge you are using.

C

UNITS CONVERTER - EPM CALCULATOR NOW AVAILABLE

Have you ever been faced with a water analysis with results expressed in units that are not your company's standard? Does a particular client require you to use units other than your standard units? Do you frequently calculate EPM loading? The French Creek Units Converter - EPM Calculator is a time saver developed just for you.



Analysis can be entered directly into the program, or a French Creek program file (e.g. WaterCycle .WAT, DownHole SAT .DHS, hyd-RO-sat .HYD) can be loaded with the Open File command. The Water Analysis Input form is very similar to the input form in all of the programs.

You can select input units form the CHANGE FROM UNITS or CHANGE TO UNITS forms. WaterCycle, DownHole SAT and hyd-RO-sat users will find the forms extremely familiar.

Converted analysis can be saved to a new French Creek format file (.WAT, .DHS. or .HYD).

The French Creek Units Converter - EPM Calculator will be included with all WaterCycle series, DownHole SAT series, and hyd-RO-sat series software packages and updates after the first of the year. Registered users with active Annual Maintenance Agreements will receive the program with their next update, or they can download the program from our web site http://www.frenchcreeksoftware.com

Other users can obtain the Units Converter - EPM Calculator for $249.

The Units Converter - EPM Calculator was added in response to user requests for such a tool. Do you need features not offered in current French Creek Software programs? Send a note to Cagliastro on our web site. Many new features in each update are user requested.

The French Creek Software Precipitant
Copyright© 1997 French Creek Software, Inc., Kimberton, PA 19442 U.S.A.