Dear Friends,
There is a Hach Instrument/ Electrode Analyser in my University to test ammonia Nitrogen in water. I called the Service Engineer of Hach company and he calibrated the instrument with 95% slope. We saved his graph too. The standard solution of 100 mg/l was reading about 101 mg/l and 10 mg/l was reading about 10.8 mg/l. Next day when I checked NH3-N with the same Hach electrode method in a municipal sewage treated effluent the repeated reading were as follows: 101.8, 98.4, 96.8, 88.4, 74.6, 65.3, 56.8, 55.9, 43.6, 38.0, 39.7, 40.8, 40.3, 36.7, 36.9, 37.5, 35.9, 35.5, 35.4, 35.6, 36.7, 37.1 and 37.4. I want to tell you all that I could not get a stable reading of NH3 as- N. What could be the reason. I am in need of an accurate and precise reading/ content of ammonia in the solution as I am working on an ammonia removal research project. Kindly guide me. Regards Lokesh Kumar Chartered Chemist, India E-mail: [email protected]
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Dear Lokesh Kumar,
Yes, if ammonia nitrogen in your sample is ranging from 0.5 to 1000 mg NH3N/L directly in reagent and effluent waters (higher concentrations can be determined following dilution of the sample) you can determine it by using Ion Selective Electrode
Please read the following publication:
Article [Study on determination of ammonia-nitrogen in water by ammo...
Good luck.
1. Do you run standard and rinsing before and after each sample.
2. Are you sampling at same location.
3. Do you think the effluent to be one concentration, or vary by location, time of day, depth, etc. Is the effluent static, or circulated.
4. If the values presented are successive dropping during the day, could there be changes related to temperature, bacterial activity, solar radiation volatility, etc. If the values have no time trend, jumping in value with no rhyme or reason, that may suggest input, output, circulation variances.
5. Do the standard concentrations give consistent readings, or also decline during the day? If the regular checking with standard produces consistent results, I would probably assume there are irregularities related to effluent concentration, making your study more difficult, and perhaps setting up a recording system for continuous sampling, with ocassional standard checks for baseline period, then after your reduction treatment period.
I think this electrode is not suitable for measuring ammonia in municipal wastewater . You can repeat the experiment with your calibration solution, 10 readings, and check if it is ok. If it isn't, the electrode has a problem.
I read the procedure to measure with this electrode and I think it is sensible to to contamination with fatty substances or particles in suspension that can block the membrane pores and, therefore, the values are decreasing.
Another possibility to determine ammonia in water or wastewater is distillation unit. Sample is first buffered at pH=9,5 with borate buffer and then distilled into solution of boric acid (if you determine ammonia with titration) or sulfuric acid (if phenate method is used).
I was using that equioment when working at WWTP and it is precise and reliable. Range of detection is from 0,1 or even 0,01 mg/L to 200 mg/L.
Dear Violeta Dediu Sir. I suppose that may be the reason with municipal treated sewage water. One more thing is that there might be other ions interference's while detecting ammonia with electrode. The electrode give consistent readings with standard solution but remains unstable when dips in sample water.
Is there any time period/ time span ( 5 minute or so...) we should give to ammonia adjuster powder pouch so that it dissolves well and give consistent readings.
Regards
Lokesh Kumar
Dear Lokesh,
In average, it takes 3-5 minutes per sample - mainly depends on ammonia concentration - higher it is, longer titration.
Regards,
Sabina
Sabina, please send me the method at my mail:
Let me try it.
Regards
Lokesh Kumar
You can also use spectrophotometric method from Hach. I worked 15 years ago with a kit including a spectrophotometer, reagents and a digestion unit. It is based on Nessler method. It was ok. You can get indicative results.
You may want to look at this web site and look at the ammonia monitor. It may be something that you want to look at in more detail.
https://www.analyticaltechnology.com/analyticaltechnology/gas-water-monitors/product.aspx?ProductID=1087
Gerold Luss
Dear Gerold Luss
Thanks for your response. Please send me this paper at:
I am not able to download it.
Regards
Lokesh Kumar
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