Bod and oxygen equivalent relationship

BOD & COD Treatment with Ozone | Ozonetech

bod and oxygen equivalent relationship

Biochemical oxygen demand (BOD) is one of the most important and widely used equivalent to secondary treatment” as removing 65 percent of the BOD and .. relationship between the response (sensor current) and BOD values ranging. 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. At least part of this oxygen demand is normally measured in a five day BOD. . dipper attached to a wooden handle, or an equivalent device, is acceptable for collecting .. The ratio of the seed BOD to mL will be used to calculate the seed.

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. Be especially careful that each drop is fully mixed into the sample before adding the next.

BOD I COD I Biological and Chemical Oxygen Demand Lec-08

It is sometimes helpful to hold the flask up to a white sheet of paper to check for absence of the blue color. The dissolved oxygen is then "fixed" using a series of reagents that form an acid compound that is titrated.

Titration involves the drop-by-drop addition of a reagent that neutralizes the acid compound and causes a change in the color of the solution. The point at which the color changes is the "endpoint" and is equivalent to the amount of oxygen dissolved in the sample.

The sample is usually fixed and titrated in the field at the sample site. It is possible, however, to prepare the sample in the field and deliver it to a lab for titration. Dissolved oxygen field kits using the Winkler method are relatively inexpensive, especially compared to a meter and probe.

Replacement reagents are inexpensive, and you can buy them already measured out for each test in plastic pillows. You can also buy the reagents in larger quantities, in bottles, and measure them out with a volumetric scoop.

The advantage of the pillows is that they have a longer shelf life and are much less prone to contamination or spillage.

The advantage of buying larger quantities in bottles is that the cost per test is considerably less.

CSERD: Dissolved Oxygen Activity

The major factor in the expense of the kits is the method of titration they use eyedropper, syringe-type titrator, or digital titrator. Eyedropper and syringe-type titration is less precise than digital titration because a larger drop of titrant is allowed to pass through the dropper opening and, on a micro-scale, the drop size and thus the volume of titrant can vary from drop to drop.

A digital titrator or a buret which is a long glass tube with a tapered tip like a pipet permits much more precision and uniformity in the amount of titrant that is allowed to pass. If your program requires a high degree of accuracy and precision in DO results, use a digital titrator.

A kit that uses an eye dropper-type or syringe- type titrator is suitable for most other purposes. The lower cost of this type of DO field kit might be attractive if you are relying on several teams of volunteers to sample multiple sites at the same time.

Meter and Probe A dissolved oxygen meter is an electronic device that converts signals from a probe that is placed in the water into units of DO in milligrams per liter. Most meters and probes also measure temperature. The probe is filled with a salt solution and has a selectively permeable membrane that allows DO to pass from the stream water into the salt solution.

bod and oxygen equivalent relationship

The DO that has diffused into the salt solution changes the electric potential of the salt solution and this change is sent by electric cable to the meter, which converts the signal to milligrams per liter on a scale that the volunteer can read. DO meters are expensive compared to field kits that use the titration method. You can also measure the DO levels at a certain point on a continuous basis.

Development of Biological Oxygen Demand Biosensor for Monitoring the Fermentation Industry Effluent

The results are read directly as milligrams per liter, unlike the titration methods, in which the final titration result might have to be converted by an equation to milligrams per liter. However, DO meters are more fragile than field kits, and repairs to a damaged meter can be costly.

This means that only one team of samplers can sample DO and they will have to do all the sites. With field kits, on the other hand, several teams can sample simultaneously. Laboratory Testing of Dissolved Oxygen If you use a meter and probe, you must do the testing in the field; dissolved oxygen levels in a sample bottle change quickly due to the decomposition of organic material by microorganisms or the production of oxygen by algae and other plants in the sample.

bod and oxygen equivalent relationship

This will lower your DO reading. If you are using a variation of the Winkler method, it is possible to "fix" the sample in the field and then deliver it to a lab for titration.

Development of Biological Oxygen Demand Biosensor for Monitoring the Fermentation Industry Effluent

This might be preferable if you are sampling under adverse conditions or if you want to reduce the time spent collecting samples. It is also a little easier to titrate samples in the lab, and more quality control is possible because the same person can do all the titrations.

bod and oxygen equivalent relationship

How to collect and analyze samples The procedures for collecting and analyzing samples for dissolved oxygen consist of the following tasks: In addition to the standard sampling equipment and apparel, when sampling for dissolved oxygen, include the following equipment: Confirm that the meter has been calibrated according to the manufacturer's instructions. Operating manual for the meter and probe Extra membranes and electrolyte solution for the probe Extra batteries for the meter Extension pole Data sheet for dissolved oxygen to record results TASK 2 Confirm that you are at the proper location The directions for sampling should provide specific information about the exact point in the stream from which you are to sample; e.

BOD & COD Treatment with Ozone

The most common sizes are milliliters mL and 60 mL. Be sure that you are using the correct volume for the titration method that will be used to determine the amount of DO.

There is usually a white label area on the bottle, and this may already be numbered. If so, be sure to record that number on the field data sheet. 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. 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.

bod and oxygen equivalent relationship

A common feature of these sensors is that they consist of a microbial film that can biooxidize the organic substrate to be quantified, sandwiched between a porous cellulose membrane and a gas-permeable membrane as the biological recognition element. First BOD biosensor was developed by immobilization of Trichosporon cutaneum on the oxygen electrode [ 5 ]. Some BOD sensors have been developed and marketed by various manufacturers in both, biofilm and bioreactor-type configurations. Most commercially available BOD sensors are flow-type systems that can be more easily automated but generally require high maintenance to prevent fouling and clogging [ 6 ].

The response is usually a change in concentration of dissolved oxygen or other phenomena such as light emission [ 7 ]. Despite the good agreement between biosensor results and conventional BOD analysis, and despite the short response time of biosensors, current BOD biosensor systems still present a series of limitations that restrict their industrial applications: It is possible to eliminate the toxic effects of heavy-metal ions by using a chelating agent that complex the ions, for example, ethylene diamine tetra-acetate EDTA and sodium diethyl dithiocarbamate [ 89 ].

bod and oxygen equivalent relationship

Prevention of contamination by other microbes is also important for a reliable biofilm-type BOD sensor [ 7 ]. Literature survey reveals many biosensors developed for BOD determination by using the different type of biological components and also different strategies of immobilization techniques. Qian and Tan [ 10 ] used heat-killed B.

  • Search form
  • Navigation menu
  • Stream Assimilation of Organic Wastes and the Impacts on Dissolved Oxygen

The immobilized Pseudomonas putida bacterium membrane was placed on the top of an optode, which was linked to a photo diode that detected fluorescence signal.