BOD & COD Treatment with Ozone | Ozonetech
The relation between K(base e) and K (base 10) is. K(base 10) The amount of BOD that has been exerted (amount of oxygen consumed) at any time t is given by. BODt = Lo – Lt = Lo (1 – e-k.t). And the five day BOD is equal to. BOD5 = Lo. BOD. Biochemical Oxygen Demand. A Conventional Perspective. 5 BOD amount of oxygen required by . BOD and oxygen-equivalent relationships. Lo. Biochemical Oxygen Demand is the amount of dissolved oxygen needed (i.e. demanded) by aerobic biological organisms to break down organic material present in a given water sample at certain temperature over a specific time period . The BOD value is most commonly expressed in milligrams of oxygen BOD is similar in function to chemical oxygen demand (COD), in that both.
If your bottle is not already numbered, place a label on the bottle not on the cap because a cap can be inadvertently placed on a different bottle and use a waterproof marker to write in the site number.What is biochemical oxygen demand ?
If you are collecting duplicate samples, label the duplicate bottle with the correct code, which should be determined prior to sampling by the lab supplying the bottles. Use the following procedure for collecting a sample for titration by the Winkler method: Remember that the water sample must be collected in such a way that you can cap the bottle while it is still submerged. That means that you must be able to reach into the water with both arms and the water must be deeper than the sample bottle.
Carefully wade into the stream. Stand so that you are facing one of the banks. Collect the sample so that you are not standing upstream of the bottle. Remove the cap of the BOD bottle. Slowly lower the bottle into the water, pointing it downstream, until the lower lip of the opening is just submerged. Allow the water to fill the bottle very gradually, avoiding any turbulence which would add oxygen to the sample.
When the water level in the bottle has stabilized it won't be full because the bottle is tiltedslowly turn the bottle upright and fill it completely. Keep the bottle under water and allow it to overflow for 2 or 3 minutes to ensure that no air bubbles are trapped. Cap the bottle while it is still submerged.
Dissolved Oxygen Activity
Lift it out of the water and look around the "collar" of the bottle just below the bottom of the stopper. If you see an air bubble, pour out the sample and try again. Remove the stopper and add the fixing reagents to the sample.
Immediately insert the stopper so air is not trapped in the bottle and invert several times to mix. This solution is caustic. Rinse your hands if you get any solution on them. An orange-brown flocculent precipitate will form if oxygen is present. Wait a few minutes until the floc in the solution has settled.
Again invert the bottle several times and wait until the floc has settled. This ensures complete reaction of the sample and reagents. The sample is now fixed, and atmospheric oxygen can no longer affect it. If you are taking the sample to the lab for titration, no further action is necessary.
You can store the sample in a cooler for up to 8 hours before titrating it in a lab. If you are titrating the sample in the field, see Task 4: Cap underwater when full. Using a DO Meter If you are using a dissolved oxygen meter, be sure that it is calibrated immediately prior to use. Check the cable connection between the probe and the meter.
Make sure that the probe is filled with electrolyte solution, that the membrane has no wrinkles, and that there are no bubbles trapped on the face of the membrane.
You can do a field check of the meter's accuracy by calibrating it in saturated air according to th e manufacturer's instructions. Or, you can measure a water sample that is saturated with oxygen, as follows.
You can also use this procedure for testing the accuracy of the Winkler method. Fill a l-liter beaker or bucket of tap water. You may want to bring a gallon jug with water in it for this purpose. Mark the bottle number as "tap" on the lab sheet. Pour this water back and forth into another beaker 10 times to saturate the water with oxygen. Use the meter to measure the water temperature and record it in the water temperature column on the field data sheet.
Find the water temperature of your "tap" sample in Table 5. Use the meter to compare the dissolved oxygen concentration of your sample with the maximum concentration at that temperature in the table. Your sample should be within 0.
BOD & COD Treatment with Ozone
If it is not, repeat the check and if there is still an error, check the meter's batteries and follow the troubleshooting procedures in the manufacturer's manual. Once the meter is turned on, allow 15 minute equilibration before calibrating. After calibration, do not turn the meter off until the sample is analyzed.
Once you have verified that the meter is working properly, you are ready to measure the DO levels at the sampling site. You might need an extension pole this can be as simple as a piece of wood to get the probe to the proper sampling point. Simply secure the probe to the end of the extension pole.
A golfer's ball retriever works well because it is collapsible and easy to transport. To use the probe, proceed as follows: Place the probe in the stream below the surface. Set the meter to measure temperature, and allow the temperature reading to stabilize.
Record the temperature on the field data sheet. Switch the meter to read dissolved oxygen. Record the dissolved oxygen level on the field data sheet.
The dropper and digital titrator are suited for field use. The buret is more conveniently used in the lab Fig. For titration with a dropper or syringe, which is relatively simple, follow the manufacturer's instructions. The following procedure is for using a digital titrator to determine the quantity of dissolved oxygen in a fixed sample: In most cases, you will use the 0.
Insert a clean delivery tube into the titration cartridge. Attach the cartridge to the titrator body. Hold the titrator with the cartridge tip up. Turn the delivery knob to eject air and a few drops of titrant. Reset the counter to 0 and wipe the tip. Use a graduated cylinder to measure the sample volume from the "fixed" sample in the mL BOD bottle according to Table 5.
Transfer the sample into a mL Erlenmeyer flask, and place the flask on a magnetic stirrer with a stir bar. Mix the sample by inverting several times.
Check for air bubbles; discard the sample and start over if any are seen. If oxygen is present, a brownish-orange cloud of precipitate or floc will appear.
Dissolved Oxygen by the Winkler Method
When this floc has settle to the bottom, mix the sample by turning it upside down several times and let it settle again. Add 2 mL of concentrated sulfuric acid via a pipette held just above the surface of the sample. Carefully stopper and invert several times to dissolve the floc. At this point, the sample is "fixed" and can be stored for up to 8 hours if kept in a cool, dark place. As an added precaution, squirt distilled water along the stopper, and cap the bottle with aluminum foil and a rubber band during the storage period.
In a glass flask, titrate mL of the sample with sodium thiosulfate to a pale straw color. Titrate by slowly dropping titrant solution from a calibrated pipette into the flask and continually stirring or swirling the sample water.
Add 2 mL of starch solution so a blue color forms. Continue slowly titrating until the sample turns clear.
As this experiment reaches the endpoint, it will take only one drop of the titrant to eliminate the blue color.