Ammonia Nitrogen In Water

Question 1

2. Operation and calibration of Thermo Scientific Meter

Answer 1

• simile to pH probe, because they operate in same machine and use different probes
• channel 2 should be selected for ammonia analysis
• before calibration, gently outlook too cord which is spring loaded cable, back and slowly release it to allow filling solution to migrate between membrane and electrode inner body
• if you feel calibration is messed up and you need to start over, use the 1 key to escape and not save changes
• when you are in menu, you may press back shortcut key to go back one screen at a time or escape to go back to main screen
• calibration needs done every 24hr
• electrode condition icon needs checked to make sure it is functioning properly. Also look at membrane on probe to see that no wrinkles or bubbles are present
• ammonia electrode should always be placed at 20 degree angle when running
• be sure samples, standards, and electrodes are near same temp
• fill beaker with 100mL of DI water and place stirring bar in beaker. Start stirrer at slow speed to minimize loss of ammonia by rapid stirring
• instrument operates better when on single screen
• select F2 to begin calibration
• volumetrically Pipette 1.0mL of 100ppm ammonia-nitrogen std into beaker. Add 2mL of ammonia pH adjusting ISA solution. Liquid should turn blue, if it doesn’t, add ISA solution in 1mL increments until it stays blue
• start calibration and when display has stopped flashing, enter 0.990 and next
• volumetrically Pipette 10.0mLs of 100ppm ammonia nitrogen standard into solution. Wait for display to quit flashing and enter 9.91
• hit cal done and log/print to save if the calibration curve is between -54 and -60
• to test calibration, run a sample with 95mL DI water, 2.0mL ISA solution and 5mL volumetrically pipetted ammonia nitrogen standard (range is in log book in titration lab)

Question 2

3. Procedure

Answer 2

• unit samples analyzed for ammonia, WWTP samples analyzed for ammonia nitrogen. When running samples they must fall between lowest and highest standards or will need diluted
• most common sample size for unit samples will be 10mL. If this is the case, use 90mLs DI water, add 10mL of sample and 2mLs ISA solution.
• allow thermo scientific meter display to stop flashing and record entry
• if another sample needs run, rinse probe with DI and begin
• after completing analysis return probe to storage solution
• if another sample needs run within next few hours, check wth standard. If out of range, recalibrate.
• if you switch back to pH channel, instrument should be calibrated before running another sample for ammonia
• be sure to turn stirrer off when all analyses complete

Question 3

4. Calculations and reporting

Answer 3

•analysis requested and sample size determines calculation 
For unit samples:
•1mL/99mL DI = reading x 121.6
•10mL/90mL DI = reading x 12.16
•100mL/0mL DI = reading x 1.216
•1mL/999mL DI = reading x 1216

Question 4

5. Troubleshoot

Answer 4

• if instrument will not calibrate within required slope readings, membrane needs changed: hold electrode vertically and unsure cap, carefully remove inner body, dispose of filling solution
• unscrew membrane cal and remove old membrane
• wearing gloves and using tweezers, carefully grasp corner of white membrane from between wax paper separators DO NOT TOUCH MIDDLE OF MEMBRANE
• align serrated edge of membrane over threads, holding membrane with thumb and gently place t over open hold
• place membrane down to align other edge with opposite shoulder
• ensure membrane surface is smooth and without wrinkles DO NOT STRETCH MEMBRANE
• screw membrane cap and fill with electrode solution LET SIT FOR 2 HOURS TO ADJUST
• insert inner body into outer body, ensure it is fully insured and then screw on electrode cap
• gently tap sodas to remove air bubbles
• soak ammonia electrode storage solution for 15 minutes before use
• of changing membrane doesn’t work, try new probe
• electrode storage solution should be changed weekly: 10mLs if 100ppm NH3 standard, 10mLs of 10N NaOH, and 980mLs of DI water

Question 5

1. Purpose

Answer 5

Several sources of ammonia throughout refinery. Sour water stripper is main source. SWS strips H2S from streams it receives and a result of stripping makes ammonia in waste stream. Nitrifying bacteria in WWTP depend on source of ammonia for food and to reproduce. Nitrifying bugs concert ammonia to nitrites and nitrates which provide nutrients for plants once released into creek. If conc of ammonia too high, bacteria cannot process. Therefore it would go through plant as ammonia and end up in outfall. Ammonia is toxic to micro organisms and aquatic life, especially in early stages of life cycle. During warm months, ammonia is much has higher effect, because more life produced.
Ammonia-nitrogen values used to operate WWTP. Our machine is calibrated for ammonia-nitrogen is nitrogen present in water that is from total ammonia in solution. Only gives nitrogen which is in ammonia. When converting from NH3-N to NH3 you must take into account hydrogen atoms in ammonia