Carefully fill a bod bottle with sample water without making air bubbles. Understanding dilution and seeding procedures in bod test target group. Appropriate protective equipment should be worn when undertaking the bod biochemical oxygen demand electrode method. Obviously, the bod test is not the most scientifically based test we perform. Biochemical oxygen demand bod standard method 5210 b 5day bod test table 1. However, this analytical method is timeconsuming generally 5 days, bod5, and the. Difference between bod and cod compare the difference. As an alternative, use the method bod calculationgraphical method on page 6 to calculate the test results. Add 2ml of manganese sulfate to the bod bottle carefully by inserting the pipette just below the surface of water. The biggest challenge in the bod test is that of time.
There are, however, some concepts you should be familiar with to obtain the best quality results. Pdf methods for assessing biochemical oxygen demand bod. The determination of chemical oxygen demand in waters. If chlorine is present in the sample, a dechlorination chemical e. Sewage was dumped in a river and it took five days for it to reach the ocean, hence the fiveday incubation requirement in the bod method. To understand the need for seeding in the bod test c. Test procedure the bod test takes 5 days to complete and is performed using a dissolved oxygen test kit. What you should know the actual procedure is so much more involved than the summary given above. The difference between the two do levels represents the. The most popular current testing method for cod involves using sealed and heated i. Standard dilution technique should be applied to samples with do depletion greater than 6 mgl. Protocol procedure and test specifications, environmental protection division, atlanta, georgia, november 1989, 31 pp.
D biochemical oxygen demand bod is the amount of dissolved oxygen needed by aerobic biological organisms in a body of water to break down organic material present in a given water sample at certain temperature over a specific time period. Biochemical oxygen demand bod is the amount of dissolved oxygen needed i. Running the biochemical oxygen demand bod test ebs. On the determination of the kinetic parameters for the bod.
For the airsaturated water calibration procedure, you either vigorously shake the solution or bubble air through it. Biochemical oxygen demand encyclopedia of life support. The bod electrode method is suitable for determining the bod of water and wastewater. Composed of two metal electrodes in contact with supporting electrolyte and separated from the test solution by a gas permeable. The determination of chemical oxygen demand in waters and. Cod often is used as a measurement of pollutants in wastewater and natural waters.
Even though the end result of bod testing is a final bod reading, the calculations are all based on do readings. The determination of biochemical oxygen demand is always a topic of discussion with. General discussion the biochemical oxygen demand bod determination is an empirical test in which standardized laboratory procedures are used to determine the relative oxygen requirements of wastewaters, ef. Methods for assessing biochemical oxygen demand bod. How to measure biochemical oxygen demand the hydrology project. Chemical oxygen demand cod is used to determine the quantity of pollution in water after wastewater treatment. What is the difference in bod, bod5, cbod and nbod, i am. Since less dissolved oxygen is available in the water, fish and other aquatic organisms may not survive. In the manual, therefore, the bis procedure for measurement of bod is 3205 part 44. Pdf the biochemical oxygen demand bod is one of the most widely used.
The bod test measures the oxygen demand due to both carbon and nitrogen based compounds. No dilution is required for samples whose 5day bod is less than 6 mgl. Also, it can be categorized in several ways such as. A glance to the united states shows that the standard methods include the dilution method as the 5210 b 5day bod test and the respirometric. Syringefilter procedure for processing samples for analysis of organic compounds by dai lcmsms this section of chapter 5 of the national field manual for the collection of waterquality data nfm describes the field procedures for collecting smallvolume samples using a syringetip filtration method. The test for biochemical oxygen demand bod is a bioassay procedure that measures the oxygen consumed by bacteria from the decomposition of. Its widest application is in measuring waste loadings to treatment plants and in evaluating a plants efficiency in removing bod. Hach bod instruments combined with hach bod reagent for biochemical oxygen demand testing help wastewater treatment plants achieve optimum bod measurement while allowing. Bod test requirements by tim loftus legend has it that the 5day bod biological oxygen demand test was developed in england. A consumers guide to bod 5 5day biochemical oxygen. Oxygen demand, biochemicaldilution method 8043 hach. After the training the participants will be able to.
There can be confusion about bod and its relationship with dissolved oxygen do readings. The biochemical oxygen demand bod determination is an empirical test in which standardized laboratory procedures are used to determine the relative oxygen requirements of wastewaters, ef. Biochemical oxygen demand bod test as described in 5210b standard methods, 20th edition, with a number of specific test requirements and differences in application. The bod5 method measures most of the carbonaceous stage of the bod typically about 60% to. The determination of chemical oxygen demand in waters and effluents 2007 methods for the examination of waters and associated materials this booklet contains guidance on methods for the determination of chemical oxygen demand using potassium dichromate solution, and notes for the disposal and recovery of selected reagents.
The bod test reflects the amount of dissolved oxygen do consumed by bacteria while oxidizing these materials. The bod level is determined by comparing the do level of a water sample taken immediately with the do level of a water sample that has been incubated in a dark location for 5 days. Understand the need and procedure for dilution and seeding in bod measurement. It describes the procedure for undiluted samples whose bod must, however, lie at a low level of between 0. Measuring bod is required as part of the environmental discharge permit and is an important parameter to evaluate the effectiveness of the wastewater treatment operation. The biochemical oxygen demand bod test tries to closely model an aerobic wastewater treatment system and the natural aquatic ecosystem.
Mar 17, 2015 biochemical oxygen demand bod bod is an empiric laboratory assay which measures the amount of organic matter contained in a water sample. The bod determination is an empirical test in which standardised laboratory procedures are. Therefore, do readings must be as accurate as possible to ultimately get accurate bod results. Bod is a timeconsuming test while cod can finish within a few hours. Biochemical oxygen demand bod testing and measurement in water. In summary, the hach system for the apha bod test uses the same reagents, sample volumes, test conditions, and principles of operation as the traditional approach. Bod is determined by incubating a sealed water under specific temperature sample for five days and measuring the loss of oxygen from. It is a variation of the bod test that measures the oxygen demand due to carbon based. Biochemical oxygen demandbod test as described in 5210b standard methods, 20th edition, with a number of specific test requirements and differences in application.
The bod test measures the molecular oxygen used during a specified incubation. Biochemical oxygen demand bod testing determines the relative oxygen requirements of wastewaters, effluents, and polluted waters. The water saturated air procedure involves storing the electrode in a sealed bod bottle containing a minimal amount of water. Georgia epd longterm bod test specifications revised january. Biochemical oxygen demand environmental protection agency. Geological surveystandard protocols and procedures. Biochemical oxygen demand, or bod, is a chemical procedure for determining the amount of dissolved oxygen needed by aerobic biological organisms in a body of water to break down organic material present in a given water sample at certain temperature over.
The key difference between bod and cod is that the bod is the oxygen demand of microorganisms to oxidize organic matter in the water under aerobic conditions while the cod is the oxygen demand to oxidize all the pollutants in the water chemically quality of a given water sample depends on some variable factors. If no residual is found, proceed with the bod analysis utilizing seeded dilution water. To check the procedure by determining the bod value of a standard glucoseglutamic acid sample 2. Two additional longterm bod procedure documents may be consulted for reference and comparison. The biochemical oxygen demand bod test is a measurement of the quantity of oxygen required by bacteria to biologically oxidize organic material under aerobic conditions. Procedure lab test for cod and bod bod test procedure 1. Pdf biochemical oxygen demand bod is a generalized parameter in the. Understanding the need and procedure for dilution and seeding in bod measurement key concepts. Only chemically digest able matter can be determined by the cod test. Bod test bottles at the laboratory of a wastewater treatment plant. Limitations test period is too long not good for process control test is imprecise and unpredictable the test is simply not very easya lot of qc makes it timeconsuming can take years of experience to master it cannot evaluate accuracy no universally accepted standard other than gga accuracy at 200 ppm vs. Geological survey usgs develops the sampling procedures and collects the data necessary for the accurate assessment and wise management of our nations surfacewater and groundwater resources. Bod primer page 2 of 61 preface the determination of biochemical oxygen demand is always a topic of discussion with regard to the method and its applicability.
Potassium iodidestarch paper can be used as a quick qualitative test for residual chlorine. Conduct a chlorine residual analysis on a portion of the sample collected. Difference between bod and cod definition, test method. The term also refers to a chemical procedure for determining this amount. Difference between bod and cod definition, test method and. Understanding dilution and seeding procedures in bod test. Biochemical oxygen demand bod biochemical oxygen demand, or bod, is a chemical procedure for determining the amount of dissolved oxygen needed by aerobic biological organisms in a body of water to break down organic material present in a given water sample at certain temperature over a specific time period. The bod determination is an empirical test in which. To ensure proper biological activity during the bod test, a wastewater sample. On the determination of the kinetic parameters for the bod test.
The holding time for a bod sample is 48 hours from collection. Method summary a known volume of sample has its initial dissolved oxygen content recorded. Determination of the biochemical oxygen demand bod in polluted waste water as a pollution indicator by incubating the bod bottles for five days at 20 degree c the amount of oxygen, taken up by the microorganisms that decompose the organic waste matter in wastewater is known as biological oxygen demand or biochemical oxygen demand. Biochemical oxygen demand bod testing and measurement in. Summary of contract required detection limits, holding. Standard methods online standard methods for the examination of water and wastewater. Bod is the amount of oxygen consumed by bacteria while decomposing organic matter under aerobic conditions. The change in do concentration is measured over a given period of time in water samples at a specified temperature. Cod determination takes less time than the biological oxygen. Summary of contract required detection limits, holding times. Mihelcic encyclopedia of life support systems eolss summary biochemical oxygen demand bod is a measure of the dissolved oxygen consumed by microorganisms during the oxidation of reduced substances in waters and wastes.
The test has its widest application in measuring waste loadings to treatment plants and in evaluating the bodremoval. Since cod uses a strong oxidizing agent, it oxidizes pollutants completely into co 2 and h 2 o unlike in bod. Dissolved oxygen is measured initially and after incubation, and the bod is computed from the difference between initial and final do. The test result should be considered as an independent measurement of organic matter in the sample, rather than as a substitute for the bod or toc test. The method consists of filling with diluted and seeded sample, to overflowing.
Oct 14, 2011 so, this is the key difference between bod and cod. The test for biochemical oxygen demand bod is a bioassay procedure that measures the oxygen consumed by bacteria from the decomposition of organic matter sawyer and mccarty, 1978. Cod is the amount of oxygen required for the oxidation of total organic matter in water. Since bod is a biochemical process, it is not a precise quantitative test. Biochemical oxygen demand bod bod is an empiric laboratory assay which measures the amount of organic matter contained in a water sample. Summary of contract required detection limits, holding times, and preservation for biochemical oxygen demand bod analytical parameter contract required detection limit crdl.
This publication is designed to provide a solid working knowledge of one of the major wastewater analytical test categories. Biochemical oxygen demand bod is also sometimes referred to as biological oxygen demand, but the latter term is considered inappropriate by many scientists and. Jun 07, 2017 bod refers to the biochemical oxygen demand, which measures the amount of dissolved oxygen do required by aerobic organisms to break down organic material present in a given water sample at a given temperature and specified time. Among the considerations for a reliable test are the following. Accurate bod measurements with electrochemical and optical probes. Overview of the two procedures for the 5day bod bod 5 test about the official procedure the procedure specified by the united states geological survey for the bod 5 test is done in the laboratory and is quite complex to perform and difficult to control for reliable results.
In order to promote public education and public safety, equal justice for all, a better informed citizenry, the rule of law, world trade and world peace, this legal document is hereby made available on a noncommercial basis, as it is the right of all humans to know and speak the laws that govern them. It measures oxygen taken up by the bacteria during the oxidation of organic matter. Biochemical oxygen demand bod is usually expressed in mgl but can also be expressed in lbsday. Accurate bod measurements with electrochemical and. Scope and application this method determines the bod of a water sample. The graphical calculation method is also a tool for. Determination of biochemical oxygen demand bod omnilab. Protocolprocedure and test specifications, environmental protection division, atlanta, georgia, november 1989, 31 pp. The oxygen content was measured using the azide method winkler modification. So that you can avoid the formation of air bubbles. The format has merely been streamlined and made more reliable to improve accuracy and save time. Thus, this summarizes the difference between bod and cod. Other related analytical values are biochemical oxygen demand bod, total organic carbon toc, and total oxygen demand tod. Dissolved oxygen is essential for the life of aquatic fauna and flora, and the bod test is a measure of the ecological impact that effluent water may have on the receiving body of water river, lake, etc.
A consumers guide to bod 5 5day biochemical oxygen demand. The bod value is calculated from the depletion and the amount of sample used. Pdf determination of biochemical oxygen demand bod without. The respirometric method can be compared to the dilution method, and standard methods are discussed in contrast to selfmonitoring methods. Determination of chemical oxygen demand of wastewater. Understanding the need and procedure for dilution and. The test usually runs for a fiveday period, but can run 7 or 10 days as well, depending on specific sample circumstances. The samples were collected and the bod test carried out according to standard methods 1980. If a residual is found, proceed with the following steps before initiating the bod test. The bod analyses were made on foodprocessing effluents bakeries and fishprocessing plants with bod 5 ranging from 629 mg1 to 938 mg1. To determine the biochemical oxygen demand bod of various samples of water b. Aug 27, 2018 biochemical oxygen demand bod testing determines the relative oxygen requirements of wastewaters, effluents, and polluted waters.
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