I'm converting a chlorine gas disinfection system to a chloramine system. Does it matter if I add the ammonia or the chlorine to the system first? thanks
Yes, if are you require to CT. Chloramine CT rates are 10 to 100 times higher than free Chlorine CT.
Two publications to get are "Chlorination and Chloramination Handbook" by Connell and "Optimizing Chloramine Treatment" AWWARF document 90620. both are available at the AWWA website and other water bookstores.
If you are not required to CT ie. you just need a residual in the distribution system then generally it does not matter (at first look).
Azertyuiop
CT is a term used in drinking wate treatment which is the concentration (C) in ppm or mg/l of a disinfectant multiplied by time (T) in minutes. Typical use is to verify complicance with the USEPA surface water treatment rule. The CT is calculated for the first customer and that value is compared to charts with variables of log removal of Giardia, pH, Temperature, and disinfectant concentration. The charts for free chlorine are signifiacantly differnent from the charts for chloramines. There are also charts for viruses which are used in ground water applications.
hydrae , are you an 'expert' in water treatment? Not one of those real experts (they know everything about nothing), but someone who can answer simple questions in a simple manner to simple persons like me ?
E.g. I have a rain water problem. That rainwater gets collected from office roofs , led to and stored in 3 underground concrete cisterns of each 10 000 liters (350 cubic feet) , as cheap office water source for the many non-consumable water points (cleaning,WC, hot water etc etc).
That water has started to stink more and more , literally. The local drugstore has given me 3x50 gr of Chloramine to mix with some water to disolve it completely , before being dumped into each of the 3 full cistern. The stench is generated by algae that should have be growing in that cistern , dixit the drugmanager , algae grow being stimulated by much warmer summer weather.
a) Is that concentration 50gr chloramine on 10 000 liter or 350ft³ of H2O enough to liquidate the algae problem ?
b) Is that concentration low enough not to attack the copper tubing of our office hot water boiler system running on that soft rain water circuit ?
Before you start using chloramine, may I suggest you order the case histories and problems associated with trichloramine more correctly referred to as nitrogen trichloride from the Chlorine Institute.
NCl3 (nitrogen trichloride) is formed when the hydrogen atoms on the ammonia molecule are replaced with chlorine atoms. For example:
(1) monochloramine has one chlorine atom and two hydrogens bound to the nitrogen.
(2) dichloramine has two chlorine atoms and one hydrogen atom bound to the nitrogen, and
(3) trichloramine or nitrogen trichloride has three chlorine atoms attached to the nitrogen atom.
Now, if you allow NCl3 to form you are setting yourself up for a disaster if the NCl3 concentrates up. First, many lifeguards have become sick due to formation of NCl3 in chlorinated indoor swimming pools. The ammonia comes from urine in the pool water. Second, in the 1930's and 1940's NCl3 was used to bleach flour. Some pet food manufactures continued bleaching flour with NCl3. However, the practice has stopped because chloramines are linked to mental disorders such as alzheimers.
Here is the best part. The holy grail in the chlor-alkali industry would be a technology that can remove chloramines from chlorine. Several chlorine plants have exploded due to NCl3.
NCl3 has the detonation velocity of C4. Likewise, it is shock sensitive. Since it is well known that NCl3 can be decomposed with UV light, several chlor-alkali plants reduce the level of NCl3 with UV lights to avoid an explosion during liquefaction or in the tail gas.
So if you expose NCl3 to UV light or drop a container containing a very small amount it will explode.
If you would like more information on NCl3 please see my US patent # 5,832,361 at US Patent and Trademark Offices website.
Oxilume has interesting points, But I disagree with his "ka-boom" as a water disinfection application, hence the reason I suggested the documentation available from AWWA. The documention goes into detail on the mono-, di-, and tri- and how to form the desirable monochloromine and avoid the undisirable di- and tri-. In all cases the concentration is in parts per million, You are already dealing with chlorine gas which of course requires special precautions. The ammonia gas also requires other special preacautions not unlike Oxilume's warnings (ammonia is a component of many dangerous products). As such, EDUCATE yourself, from multiple sources, books, other local utilities, suppliers...
Many water utilites use monochloromine as a residual disinfectant which is useful for preventing the further formation of disinfection byproducts.
Azertyuiop
I am a practicing Engineer in the water field, expert, that is for others to decide.
As stated before, monochloromine is not as strong of a disinfectant as free chlorine, as such it has a harder time killing the "bugs". your drugstore tablets?? I am not familiar with them.
It does not sound like enough even if it was calcium hypochlorite which provide free chlorine.
For corrosion issue. There are many factors to determine how your piping will react to any treatment, and boilers require special treatment in accordance with local and national codes.
I did not suggest an explosion within a drinking water treatment plant or in the distribution system.
The information I passed alone was from a HS&E point of view.
NOTE: The water source (surface or aquifer) may already contain ammonia. So if you use breakpoint chlorination, in addition to an ORP meter for disinfection purposes to control for a "Free" Chlorine residual within the distribution system you will form NCl3.
However, it is highly unlikely that NCl3 will concentrate up to a dangerous explosive level at the WTP or within the distribution system.
Ask yourself this question -WWWA here does the Aget its information on chlorine? Hint - Chlorine Institute.
Also, if you ever get the chance please visit a chlor-alkali facility. Ask plant engineers about the ammonia in the brine and where does it orginate? I'll give you a hint:
The brine is produced from a salt dome. The salt within the salt dome is leached out with well water. In some cases, the objective is to increase the natural gas storage capacity of the salt dome. The ammonia orginates from the well water.
Also, here is another point - what is the oxidation potential of mono-chloramine?
sorry , guys , I want to stay out of the discussion in the future , given that my problem is not related to the posted inquiry on top of the thread.
I have taken a sample of my bad smelling cistern water to the local drugstore , asked them how to remove the bad smell , and they answered me that this smell was from algae grow due to the warmer summer water temperatures.
They gave me a powder (chloramine) , 50gr per 10 000 liter cistern , and after proper mixing by use of submerged removable water pump , purging of the water distribution circuits and cleaning of the water filter , I must declare that the bad smell has gone away.
If the bad smell comes back , I will re-disolve 50gr in each cistern to solve my problem.
