What are the differences between chemical oxygen demand cod and biological oxygen demand bod. The river water quality data used in this study is obtained from the river water sampling conducted for. Chemical oxygen demand an overview sciencedirect topics. Cod is closely related to bod or biochemical oxygen demand, the difference being that bod is a test of the level of organic matter that can be biologically oxidised while cod is a test of the amount of organic matter that can be chemically oxidised.
This professional, waterproof meter complies with ip67 standards and measures do, barometric pressure, bod and temperature. There is no statistical difference between the bod5 and cbod5 values for either sampler. The biochemical oxygen demand bod test tries to closely model an aerobic wastewater treatment system and the natural. Both cod and bod test methods aim to give an indication of the amount of pollution in a water sample. General discussion the biochemical oxygen demand bod determination is an empirical test in which standardized laboratory procedures are. Wastewater treatment modeling acknowledgments glossary bibliography biographical sketches. After dilution, the resulting difference between the initial and final do reading. 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.
Biochemical oxygen demand bod is a way to measure organic pollution in water by looking at the rate at which microorganisms in the water use up dissolved oxygen when they metabolize the organic pollutants. Almost all wastewater treatment plants are required to measure one of. Atlantic cod and pacific cod that inhabit different oceans. Oct 14, 2011 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. Aug 24, 2017 bod refers to the dissolved oxygen used by microorganisms in the biochemical oxidation of organic matter whereas cod refers to the oxygen equivalent of the organic material using dichromate in acid solution. Cod or chemical oxygen demand is the total measurement of all chemicals in the water that can be oxidized. What are the differences between chemical oxygen demand. For a completely biodegradable wastewater such as glucose, approximately ten percent of the original organics remain as nonbiodegradable cellular residues after biological oxidation. Biochemical oxygen demand bod is the amount of dissolved oxygen needed i. Organics 2 university of georgia cooperative extension circular 922.
Bod refers to the dissolved oxygen used by microorganisms in the biochemical oxidation of organic matter whereas cod refers to the oxygen equivalent of the organic material using dichromate in acid solution. The chemical oxygen demand cod test is commonly used to indirectly measure the amount of organic compounds in water. D bod is only a measure ment of consumed oxygen by. When you purchase cod in 2011, it is almost certainly pacific cod, due to its sufficient numbers in the wild. The hi98193 is a rugged, portable dissolved oxygen do meter designed for demanding applications. Cash on delivery cod is a type of transaction in which the recipient makes payment for a good at the time of delivery. The amount of oxygen required by microorganisms to stabilize decomposable organic matter present in a certain volume of a sample of water, is called biochemical oxygen demand bod. Bod and cod are currently used for water quality indices, but adoption of toc is being suggested. Cod or chemical oxygen demand is the total measurement of all chemicals. Hence, the cellular residues are not measured by the bod test. Cod should always measure higher than toc and then bod. Study of raw wastewater bod5 and cbod5 relationship. What is the difference in bod, bod5, cbod and nbod, i am. Therefore, for a given water sample, the cod is always greater than the bod, and the second result cod, as the complete chemical oxidation of the sample, can be considered to.
It is often used ambiguously in relation to carbonaceous oxygen demand cbod which is the oxygen consumed during the oxidation of carbonaceous compounds to carbon dioxide co2. Cod is the amount of oxygen required to chemically breakdown the pollutants whereas bod is the amount of oxygen required to do this biologically. D bod is only a measure ment of consumed oxygen by aquatic microorganisms to decompose or oxidize organic matter. Toc or total organic carbon is the measurement of organic carbons.
Both the parameters test the oxygendemanding strength of the wastewaters. These data suggest that nitrification is not occurring in the. Differentiate between bod and cod chemistry environmental. Jul 20, 2016 cod or chemical oxygen demand is the total measurement of all chemicals in the water that can be oxidized. Lingcod buffalo cod, bluefish, white cod this bottomdwelling fish acquired its name because of aresemblance to cod and ling fish. It is often used ambiguously in relation to carbonaceous oxygen demand cbod which is the oxygen consumed during the oxidation of carbonaceous compounds to carbon dioxide co2 and other oxidized end product. Cod is the amount of oxygen required to chemically breakdown the pollutants whereas bod is the amount of oxygen required. The m ain difference between b od and cod is that bod is the amount of oxygen which is. Study of raw wastewater bod5 and cbod5 relationship yields surprising results. Difference between bod and cod definition, test method and. Nitrification is inhibited so that only the oxidation of cod occurs.
In general with chemical destruction you can remove more polution than with the biological way. Bod measures the oxygen demand for the decomposition of organic. Bod, bod kinetics and cod tests are discussed at length. Biochemical oxygen demand bod and chemical oxygen demand cod both measure the quantity of organic compounds found in water. Bod measures the amount of oxygen required by the aerobic organisms to. The main difference between bod and cod is that cod measures all organic material, while bod only measures organic material which is or can be biologically degraded. Quality of a given water sample depends on some variable factors. The main difference between bod and cod is that bod is the amount of oxygen which is consumed by bacteria while decomposing organic matter under aerobic conditions whereas cod is the amount of oxygen required for the chemical oxidation of total organic matter in. For most people a complete understanding of the standard methods required to accurately complete critical wastewater analytical tests is not necessary. Bod is the amount of oxygen consumed by bacteria while decomposing organic matter under aerobic conditions. A parameter of water quality which measures the amount of oxygen in parts per million required to oxidize organic and oxidizable inorganic compounds in the water sample. Typically, the average bod result is divided by the average cod result to find a conversion factor between the two parameters. Cod is the amount of oxygen required to chemically breakdown the pollutants whereas bod is the amount of oxygen required to do this. What is the difference in bod, bod5, cbod and nbod, i am so.
Chemical oxygen demand cod vs biological oxygen demand bod. Bod is calculated by peeping a sample of water containing a known amount of oxygen for 5days at 20c in bod incubator. 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. Chemical oxygen demand cod and biological oxygen demand bod are the two main characteristic properties that indicate the strength of sewage. These parameters reflect effect and material characteristics of one or more substances. The main difference between bod and cod is that bod is the amount of oxygen which is consumed by bacteria while decomposing organic. Bod refers to the biochemical oxygen demand and cod is the chemical oxygen demand. Cod chemical oxygen demand is the amount of oxygen required to degenerate all poution in a chemical way by adding oxidising agents and heating. Since the introduction of the closedreflux micro method in the early 1980s, cod analysis has become increasingly used at municipal wastewater treatment plants for process monitoring and to aid in process control. A read is counted each time someone views a publication summary such as the title, abstract, and list of authors, clicks on a figure, or views or downloads the fulltext. There are 4 common tests to determine organic pollution in wastewater. Sivanandan 11 water plant calculation for a completely biodegradable wastewater such as glucose, approximately ten percent of the original organics remain as nonbiodegradable cellular residues after biological oxidation.
It is therefore used as the measure of the amount of certain types of organic pollutants. Bod technically stands for biological oxygen demand bod5 means the test has been run for 5 days. Rockfish rock cod, pacific snapper neither a cod nor a snapper, this finfish shares their firmtexture, white flesh, and mild flavor. However, a fundamental understanding of the theory behind and working knowledge of the basic procedures used for each test, and the answers to commonly asked questions about each test can be a valuable tool for anyone involved in generating. This survey was conducted to obtain basic data about organic matter such as bod biochemical oxygen demand, cod chemical oxygen demand, doc dissolved organic carbon and toc total organic carbon in agricultural water in gyeongnam province. Pdf comparison of bod, cod, toc and doc as the indicator. Cod value is always greater than the bod value of a particular water body. A special chemical is added to kill the autotrophic bacteria so nitrification is inhibited so that only the oxidation of cod occurs. Cod is the amount of oxygen required for the oxidation of total organic matter in water. This requires historical data of bod and cod measurements taken over a period of time. It is a test of the amount of oxygen required to oxidise organic matter in a sewage sample by chemical oxidation with a powerful oxidising agent such potassium dichromate.
Dec 16, 2015 deals with the measurement of organic matter concentration in water and wastewater. What are the differences between chemical oxygen demand cod. Other sources of oxygenconsuming waste include stormwater runoff from farmland or urban streets, feedlots, and failing septic systems. Whereas, chemical oxygen demand cod is the amount of oxygen required to oxidize and stabilize the organic and inorganic matter present in a certain volume of. Jun 07, 2017 difference between bod and cod definition. Cod stands for chemical oxygen demand where bod stands for biochemical oxygen demand. The relationship of bod and cod of river water for three rivers in malaysia are investigated over a period of one year. Biochemical oxygen demand and carbonaceous oxygen demand. Almost all wastewater treatment plants are required to measure one of these three items as a measure of the pollution value in the water. Cod correlation provides operations, laboratory benefits. Bod and cod to characterise wastewater nihon kasetsu. The difference between the two do levels represents the amount of. Although, some of the organic compounds, which can be broken down by microorganisms, are countable for the biological oxygen demand, they may not be encountered in measuring chemical oxygen demand c.
Chemical oxygen demand cod is the total amount of oxidisable organics biodegradable and nonbiodegradable and both dissolved and particulate, measured by the amount of oxygen in the form of oxidising agent required for the oxidation of organic matters by heating the sample in strong sulphuric acid containing potassium dichromate 14. Difference between bod and cod compare the difference. Bod5 measures the oxidation of carbons and possibly nitrogenous compounds present in a water sample. Bod and cod to characterise wastewater nihon kasetsu europe. The most popular sum parameter in waste water analysis are the bod biochemical oxygen demand, cod chemical oxygen demand, tod total oxygen demand and toc total organic carbon. Biochemical oxygen demand and chemical oxygen demand. Further, as part of the ultimate bod measurement, other associated tests like dissolved oxygen and ammonical, nitrate and nitrite forms of nitrogen are also discussed. Lingcod is a favorite withrecreational anglers on the west coast. The bod test takes 5 days to complete and is performed using a dissolved oxygen test kit. Increased bod, conductivity, decreased cod, ph, hardness, alkalinity and significant release of so 42 confirm the mineralization of the polluted water during this treatment process. Pdf can be found in find, read and cite all the research you need on researchgate. 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 measures the quantity of oxygen consumed by microorganisms during the decomposition of organic matter.
Biochemical oxygen demand and carbonaceous oxygen demand of. Correlation between biochemical oxygen demand and chemical. Waterproof portable dissolved oxygen and bod meter hi98193. For example, the organics in a wastewater sample represented by bod will also. Biochemical oxygen demand bod is a measure of the dissolved oxygen consumed by microorganisms during the oxidation of reduced substances in waters and wastewaters. A full explanation of any of the parameters can be found by clicking on the blue links. Deals with the measurement of organic matter concentration in water and wastewater. Formula sheet for all wastewater operator exams revised 8. The amount of oxygen consumed by these organisms in breaking down the waste is known as the biochemical oxygen demand or bod. Correlation between bod, cod and toc 191 exponential equation is fitted for the observed behaviour of bod as a function of cod. Chemical oxygen demand cod vs biological oxygen demand. As nouns the difference between cod and ling is that cod is obsolete a small bag or pouch or cod can be a marine fish of the family gadidae or cod can be a joke or an imitation while ling is any of various marine food fish, of the genus molva, resembling the cod.
What is the significance of bod and cod in water quality. Difference between bod and cod definition, test method. Most applications of cod determine the amount of organic pollutants found in surface water e. The main difference between bod and cod is that bod is the amount of oxygen which is consumed by bacteria while decomposing organic matter under aerobic conditions whereas cod is the amount of oxygen required for the chemical oxidation of total organic matter in water. The basic features of cod, bod and their basic differences are explained in this article. Bod primer page 4 of 61 biological background of all bodn determinations the primary difference between bodn determination and other measurements such as ph, conductivity, oxygen, cod, nitrate, etc. Cod or chemical oxygen demand is the total measurement of all chemicals in the water. A discussion of bod and how to monitor it is included at the end of this section. Almost all treatment plants are required to measure one of these three items as a measure of the pollution value in the water. Bod, cod, toc and tod sum parameters in environmental.
The main objective of the analysis was to investigate the relation between biochemical oxygen demand bod and chemical oxygen demand cod. It is important that the bod test is carried out at. Technologybased effluent limitations 55 appropriate contiguous geographical area by waste stabilization ponds that are achieving the levels of effluent quality for bod5 specified in 3. Difference between biochemical oxygen demand bod and chemical oxygen demand cod article shared by. The name cod refers to two separate species of fish. Biochemical oxygen demand bod can be estimated from chemical oxygen demand cod measurements, if a correlation is established. Cod is usually measured and the test is simple and easy to perform with the right equipment and can be done in 2. Buy or eat black cod and you are enjoying sablefish, which resembles the cod, but comes from a different family. Bod biochemical oxygen demand is supposed to measure the amount of food or organic carbons that bacteria can oxidize. Biochemical oxygen demand bod and chemical oxygen demand pdf. Difference between biochemical oxygen demand bod and. Cbod means only the carbonaceous biochemical oxygen demand nbod means nitrogenous biochemical oxygen demand bod5 typically includes cbod and nbod unless one or the other is inhibited.
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