Can amonia be removed prior to the DI's?

[ReefRelated]

I posted this on another thread but I would like to find some more answers. Maybe you can help.

I have 2 questions I would like answered. Can catalytic carbon in a fine mesh form remove amonia? I understand it can break the chloromine bond and remove the actual chlorine but does it actually remove the amonia?

Here's another question. There has been some talk on this thread about removal of amonia by the RO membrane. Does or can an RO membrane remove amonia. I understand differences in PH can play a factor but some people I talk to say the membrane can remove amonia and some say it will not. Yes or No?

I talked to someone today who claims that the carbon nor the membrane will remove the amonia. The DI's will be left to handle that. I am questioning this. I hope someone can tell me otherwise with proof. From what I understood from all this reading is that the amonia could be removed prior to the DI's.

[ichthyman]

Tonytooth,

Found this on Dow’s website in the question and answers guide of the Flimtec section. I
guess we were not the only ones with this question.

Question

How well do FILMTECTM RO membranes reject ammonia and nitrate?

Answer

Dissolved gases like ammonia (NH3) will not be rejected by an RO membrane; however,
NH3 is in equilibrium with the ammonium cation (NH4+), as defined by the following
equation:

NH3 + H+ --- NH4+

Decreasing the pH and/or temperature will convert NH3 to NH4+, which is rejected by
the FILMTEC RO membrane. For example, as long as the temperature and pH are less
than 40°C (104°F) and 7 respectively, more than 95% will be present as NH4+ and the
rejection should be better than 98%. However, if both parameters are allowed to increase,
the amount of ammonia will also increase, accompanied by a corresponding decrease in
rejection by the RO membrane.

Nitrate (NO3) rejection is pH dependent. Typically, its rejection ranges from 70 to 95%.


Charles,

Not to highjack Tony’s post put I have few related questions of my own. Does a water
softener lower pH? If so, would a drop from 8.1 to 7.0 or below be possible? Also what
would the effects on a R.O./D.I. system if a water softener was used for prefiltration?

Thank you for your time,

John Reiter -owner
FISH and other ICHTHY stuff

[ReefRelated]

Also I would like to know if the catalytic carbon can remove amonia?

http://www.calgoncarbon.com says "Centaur accelerates reaction rates without the use of impregnates for many applications including odor control, chloramine removal, phosphine abatement and others."

This tells me it can remove amonia. Many different sites say that this catalytic carbon removes chloromines. Chloromines are clorine and amonia so if they are removing chloromines then it should include the amonia also.

http://www.apswater.com says "Centaur carbon removes both chloramine and hydrogen sulphide from potable water. Centaur is outstanding in VOC removal, taste and odor control and in operating efficiency when compared with traditional activated carbons."

If they say it removes chloromines then I would have to assume the amonia is being removed also otherwise I would consider these as false statements.

[SpectraPure]

I posted this earier to the wrong thread, so here it is again.


Catching up on the questions of the day:

Q.: Can catalytic carbon in a fine mesh form remove ammonia?

No

Q.: Does or can RO membranes remove ammonia?

Yes.

If your tap water is naturally acidic, the membrane will remove ammonia. But, this is not the typical case. Most tap water is above 8.0 pH and some are above 9.0pH. Our usual solution to this high pH problem with chloramines is to inject hydrochloric acid (HCL) into the feed water to adjust the pH to about 6.0. This accomplishes three things: it neutralizes the hydroxides, converts monochloramines to dichloramines that are readily removed by the carbon prefilters and lastly any free ammonia (NH3+) is converted to the ionized ammonium form. The ammonium ion is well rejected by the RO membrane and in the acid pH range, the swollen membrane pores return to normal with no lasting damage.

AND,

As quoted by ichthyman:

Question

How well do FILMTECTM RO membranes reject ammonia and nitrate?

Answer

Dissolved gases like ammonia (NH3) will not be rejected by an RO membrane; however,
NH3 is in equilibrium with the ammonium cation (NH4+), as defined by the following
equation:

NH3 + H+ --- NH4+

Decreasing the pH and/or temperature will convert NH3 to NH4+, which is rejected by
the FILMTEC RO membrane. For example, as long as the temperature and pH are less
than 40°C (104°F) and 7 respectively, more than 95% will be present as NH4+ and the
rejection should be better than 98%. However, if both parameters are allowed to increase,
the amount of ammonia will also increase, accompanied by a corresponding decrease in
rejection by the RO membrane.


Q.: Does a water softener lower pH?

No, water softeners remove calcium and magnesium ions, not HCO3, which is responsible for high pH.


Q.: Also what would the effects on a R.O./D.I. system if a water softener was used for pre-filtration?

Wonderful !!! Again, removing calcium and magnesium from the feed water will increase the life of the membrane. We see all the time, erroneous information that you should never place an RO system downstream of a water softener. This is the preferred configuration for long membrane life.


Q.: Also I would like to know if the catalytic carbon removes ammonia?

Again, NO.


Q.: If they say it removes chloramines then I would have to assume the ammonia is being removed also otherwise I would consider these as false statements.

Consider them as false statements. Catalytic carbon does NOT remove ammonia.


Charles Mitsis
President, SpectraPure, Inc