Sunday..!

• went to environment laboratory, level 3..(BOD, withdraw samples and measuring pH)
• bought some lauk for shedan, he wanted tempe at medan selera section 7 shah alam
• went back home, lunch and wait for husna to arrive..

BOD-some basic explanation

BOD (Biochemical oxygen demand) is a measure of the amount of oxygen that bacteria will consume while decomposing organic matter under aerobic conditions.

COD (Chemical oxygen demand) is a measure of the total quantity of oxygen required to oxidize all organic material into carbon dioxide and water.

*COD values are always higher than BOD values

DO meter, step by step..

This is only for YSI 5000 model for DO meter

Switch on, wait for 15 minutes (until stable value appear) then only press CALIBRATE..follow the procedure as in pictures below:

press calibrate, leave for few minutes until stable condition achieved

press autocalibrate, wait until it appears as "DO calibration saved"

press mode to go back to original screen

now only measurement can be taken after calibration has been done and saved!!

Make sure probe is always in good condition...maintaining it is very important..

Probe should be cleaned, color as the pic above

• membrane should be changed frequently if usage is high
• if possible, look at the KCl as well, to prevent from any damage on the membrane, add KCl if its not enough, must prevent from any bubble when adding KCl..be careful
• probe should be change at least once a year
• must wipe membrane with soft tissue after rinsing it with distilled water
• extra precaution must be taken to prevent from any damage to membrane, its expensive. cost about rm400/membrane
• price for probe, rm4000
• price for meter, rm10000
• so take extra careful when using DO meter..its so expensive!

for more info, click here

Step by step in preparation of BOD using DO probe

Step by step:

1. Preparation of Dilution Water
2. Preparation of BOD bottles
3. Read the dissolved oxygen content in the five BOD bottles using a dissolved oxygen probe. Ensure that no water is lost from the BOD bottles. Replace the stoppers without trapping any air.
4. Place the BOD bottles in the incubator. To prevent oxygen from leaking into the bottles during the incubation period, fill the portion of the bottle around the stopper with water using a squeeze bottle. It is the responsibility of the laboratory group to ensure that the water seal on the BOD bottles is maintained by checking each day and replenishing as required using a squeeze bottle of distilled water.
5. Following 5 days, remove the BOD bottles from the incubator and determine the dissolved oxygen concentration of each.
6. Compute the BOD using the following formula

BOD mgL= [(Initial DO-Final DO) x 300mL] / mL sample

check out this link:

BOD procedure

Bod method

link to YSI 5000 manual

• avoid using detergents to clean the bod bottles
• use chlorine/bleach to clean it, to disinfects any microbes

Happiest moment!

Happiest moment? whats with it?? hehehe...

Im currently waiting for my primers to arrive, the supplier will send it to me at any time now...

Ive ordered 14 primers, its for the fingerprinting of Sulphate reducing bacteria (SRB) in my biofilm reactor! Im planning to proceed with the DNA thing during the fasting month, so i dont have to take wastewater sample during that month..Pity those Bangladesh people, coz they are the one who help me to sample and carry the 30L of wastewater.

primers

Oh by the way, Ive received my chemicals yesterday, manganese (II) nitrate tetrahydrate and zinc (II) nitrate hexahydrate..I can just proceed coz I already have the 3 metals that I want!

chemicals

ICP-LESSON 1

things that u must make sure before running ICP,

1. check gas
2. tore samples
3. check tubing

To warm up ICP:

1. Switch on plug of ICP, PC, Chiller
2. Check gas, open the gas tank, both on the gas tank & on the wall to green color.
3. Check air compressor (push the red button to the back, open the blue screw on the right and 1 more screw on the bottom. Shake that air compressor, just to make sure, water flows out coz condensation occurs.
4. Re-tighten the screw back and pull the red button to the front.
5. On ICP generator button, its on the right side.
6. Open the winlab 32
7. Click F11
8. Lock the yellow and white tube
9. To wet tubing, click on Plasma control
10. On pump
11. After no bubble seen, off the pump
12. On plasma, wait to 5 mins
13. stabilize, minimize window for plasma control
14. Click Auto, cancel -Print log during analyses
15. Result data set name
16. open, re-name; name and description
17. click analyze
18. check back with the Location and Samples ID type previously
19. If OK, click analyze ALL
20. go to Spectra to check for calibration