Share the problems you encountered while conducting water quality analysis, as well as your work experience
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This post was last edited by zbx on 2011-10-24 at 15:46. Have you encountered any problems when analyzing water quality, and how did you solve them? What is the reason? Share your work experience with everyone else, and let’s see who made the most mistakes or had the most embarrassing situations, haha. Spam is strictly prohibited. Thank you. Inspection items, any abnormal conditions or phenomena that occur, solutions and measures taken, as well as what should be done in the future: 1. pH measurement 2. Turbidity measurement 3. Alkalinity measurement 4. Total hardness measurement 5. Calcium ion measurement 6. Chloride ion measurement 7. Iron ion measurement 8. Sulfate measurement 9. Silica measurement 10. Residual chlorine measurement 11. Suspended solids measurement 12. Total suspended solids measurement 13. Total inorganic phosphate measurement 14. Total phosphate measurement 15. Chemical oxygen demand measurement 16. Total bacterial count measurement 17. Others
Let me start. Once, when conducting a test on water hardness, the results differed significantly from the usual values. I wasn’t sure what the cause was; it took some time to figure it out, and it turned out that one of my staff members had prepared the buffer solution incorrectly, which led to an error in the measurement results: lol
My second point: I remember the first time I used the potassium dichromate method to determine chemical oxygen demand; I noticed that the blank sample turned green as soon as it was heated. It took me a long time to figure out why, and eventually I realized that the bottles just purchased, as well as the anti-boiling glass beads, needed to be boiled in potassium dichromate until they no longer changed color. Are there any other kids like me, hehe
When performing COD analysis, boiling over occurred, causing the condenser to be flushed out
When measuring dissolved oxygen in wastewater, after adding starch and reaching the endpoint, it turns blue again after a short while. What could be the reason? I think it might be due to a high oxygen content; or perhaps too much sulfuric acid was added
Reply to 5# Lab Assistant: After reaching the endpoint in the iodometry titration, if the sample is left alone for some time, air will oxidize a small amount of iodide ions, causing it to turn blue again; this has no impact on the titration results.
The last edit to this post was made by Plower on 2011-11-14 at 07:04. There are several valid standards for the determination of sulfides, as compiled by xwtsq: 1. GB/T 16489-1996 \"Water quality – Determination of sulfides – Methylene blue spectrophotometric method\": http://kjs.mep.gov.cn/hjbhbz/bzw...t19970101_67346.htm； 2. GB/T 17133-1997 \"Water quality – Determination of sulfides – Direct colorimetric spectrophotometric method\" ； http://kjs.mep.gov.cn/hjbhbz/bzw ... t19980501_67539.htm 3. HJ/T 60-2000 \"Water quality – Determination of sulfides – Iodometric method\": http://kjs.mep.gov.cn/hjbhbz/bzw ... t20010301_67525.htm ； 4. HJ/T 200-2005 \"Water quality – Determination of sulfides – Gas molecular absorption spectrometry\": http://kjs.mep.gov.cn/hjbhbz/bzw... t20060101_71681.htm ；
For pH measurement, there was once a complaint about issues with the quality of the chemicals used; the pH level of those water treatment chemicals was only around 5. I immediately realized that something was wrong, as it should generally be below 2 – how is that possible? I rushed over to check, and only then did I realize that the pH test strips they were using had a range of 5 to 8; haha, it was just a false alarm!
Determination of P in wastewater? http://bbs.hcbbs.com/thread-909672-1-2.html
When measuring p, the level of inorganic phosphorus was found to be higher than that of total phosphorus
There are so many problems; I just can’t tell the endpoint for measuring chloride ions: what color is brick red?； That spectrophotometer used for wastewater analysis isn’t accurate at all; the formula used to describe the curves is also incorrect ； How exactly should a pH meter be calibrated? My crappy device has calibration solutions that are almost expired. Why does the slope for total phosphorus keep changing every time it’s calculated?