Dave Russell Forum Moderator 30 Posts
Re: What is the environmental impact of this specific waste mixture?21 August 2014 at 12:18pm
I'm having a tough time finding tetra ammonium citrate in the chemical databases I use, and if there is a better name, I could possibly provide more information. The names provided are "plant" names rather than the IUPC or descriptive names.
However, the solution will have a high oxygen demand, the references for ammonium citrate is generally for Di-ammonium Citrate, and/ or iron citrates, but I suspect that the ammonia concentration will be extremely high, and there is the possibility that any substantial discharges will result in a fish kill or pH decrease in the liquid being discharged. The DAC is moderately alkaline, but I could not obtain vapor pressure data on the compound because it is normally solid. At higher values of pH above 8, the ammonia will tend to offgas, and that is particularly strong at pH>8.3
The compound, in water, will dissolve and may have a strong ammonia odor, possibly noxious or irritating to the respiratory tract and eyes. Recommended handling procedures might include respiratory protection, half face mask at a minimum with ammonia cartridges, face shield and goggles to reduce the effect of fumes, or using an air line or powered air purifying respirator when handling or approaching the material. protective gloves and tyvek splash suit and perhaps boots are also indicated.
Sorry that I can't help further. With more information on the compounds, I can probably provide better evaluations.
Dave Russell Forum Moderator 30 Posts
Re: What is the environmental impact of this specific waste mixture?2 September 2014 at 10:58am
Editor's Note: The questioner provided additional information. For proprietary reasons we are not providing that detailed report. We are only providing Dave Russell's response.
Here are a couple of additional thoughts.
The additional information indicated that the ammonia concentration in the solution is quite high. At the 90-95C temperatures and pH above 9.5 the unreacted ammonia will tend to strongly offgas, and handling the solution could be irritating to the nose and eyes, so proper PPE is mandated. There is also a retracted (vacated) OSHA PEL TWA of 1 mg/CuM which is still enforced in some states. [reference: http://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?cid=14457#x332]
The chemical literature suggests that the tri ammonia form is the most common and stable. The raising of the pH above 8.3 will produce more free ammonia and higher aquatic toxicity from free ammonia. A 1979 report: Aqueous Ammonia Equilibrium- Tabulation of percent -un-ionized ammonia EPA No 600/3/79/091 makes the case in 106 pages of tablular data. [http://nepis.epa.gov/Adobe/PDF/30000I7U.PDF]
The attached image (amonia_fig1) illustrates the same point, and at pH 9-9.5 you have about 20% of the available ammonia converted to the free ammonia form, and potentially off-gassing. But there is a more significant point. In 2013 the EPA revised the fresh water quality criteria at pH7 from 24 mg/l Total Ammonia Nitrogen (TAN) to 17 for acute water quality criteria, and set the 30 day rolling average at 1.9 mg/l . At pH 8, the 1 hour value is 5.6 mg/l, and the 30 day is 1.2 mg/l.
So the answer the questions raised by the client:
1) Yes, there is potential aquatic toxicity if the material is spilled and then discharged to a waterway. Fish kills could be expected.
2) I have every reason to believe that the free ammonia levels can be reduced dramatically by simple aeration.
3) the material is biodegradable when fed to a wastewater treatment plant at a reasonable rate.
4) the iron salts may be desirable in the treatment plant to reduce phosphate levels in their effluents, but that's not determined. A simple test or treatability study with the local POTW may be in order.
5. My best guess on post processing spills, and accidental releases, is that the material will cause an environmental event if in high concentrations in wastewater or fresh waters.