A cod test can be used to easily quantify the amount of organics in water. Example of a bod determination 200 ml of waste water was collected, aerated and seeded with bacteria. What are the differences between chemical oxygen demand cod and biological oxygen demand bod. The bod 5 cod and the bod 5 cod sol ratio, as highlighted earlier, are in line with the indices on solid phase, except in the case of results from static leaching test of 6h duration, in particular for waste a and b. Bod is the amount of oxygen consumed by bacteria while decomposing organic matter under aerobic conditions.
Also, it can be categorized in several ways such as biological, physical and. Cod testing also gives the fast measurements required in many treatment systems for informed decisions regarding process control adjustments. Both cod and bod test methods aim to give an indication of the amount of pollution in a water sample. Almost all treatment plants are required to measure one of these three items as a measure of the pollution value in the water. A major difference between the cod and the bod test, is that in the bod test ammonium is biologically oxidized to nitrate, whenever this nitrifying capacity is available. 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. Environmental protection agency, athens, ga manual which describes. What are the differences between chemical oxygen demand. The difference in weight of the dry filter before and after solids are passed through is the tss milligrams mg of suspended solids per liter l of wastewater filtered. The main difference between bod and cod is that bod is the amount of oxygen which is consumed by bacteria while decomposing organic.
Cod is the amount of oxygen required to chemically breakdown the pollutants whereas bod is the amount of oxygen required to do this. Example of a bod determination a much better nickname the. The m ain difference between b od and cod is that bod is the amount of oxygen which is consumed by bacteria while decompo sing organic matter under aerobic con ditions whereas cod is the amount. How are your cbods ohio water environment association. Cod or chemical oxygen demand is the total measurement of all chemicals in the water that can be oxidized. D bod is only a measure ment of consumed oxygen by aquatic microorganisms to decompose or oxidize organic matter. Biochemical oxygen demand, biological oxygen demand, chemical. The soluble bod is a measure of how much food for microorganisms is dissolved in the water being treated. Biochemical oxygen demand bod represents the amount of oxygen consumed by bacteria and other microorganisms while they decompose organic matter under aerobic oxygen is present conditions at a specified temperature. Chemical oxygen demand cod vs biological oxygen demand bod. The qvalue curve for bod used in calculating a water quality index2 illustrates the relationship between bod and water qualitythe higher. These definitions vary within the state, examples are as follows. Bod, bod kinetics and cod tests are discussed at length. This inexpensive tss test tells much about the wastewater character and can be run in less than two hours with fairly inexpensive equipment.
Many industrial and municipal laboratories find that parallel cod and bod testing is beneficial because the cod. Application report the importance of biochemical oxygen. Biochemical oxygen demand bod is a chemical process for determining the amount of dissolved oxygen required for aerobic biological organisms in a body of water to break down disintegrate. Cod values which are in the order of magnitude similar to values reported in the literature. Thermolab bod incubators provide with accurate conditions and. Dec 16, 2015 deals with the measurement of organic matter concentration in water and wastewater. Biological oxygen demand is an important water quality parameter because it greatly influences the concentration of do that will be in the water.
The single coagulation process increased the bod biological oxygen demand cod chemical oxygen demand ratio by 0. Environmental protection agency method detection limit mdl procedure found in title 40 code of federal regulations part 6 40 cfr 6, appendix b, revision 1. Most applications of cod determine the amount of organic pollutants found in surface water e. Many industrial and municipal laboratories find that parallel cod and bod testing is beneficial because the cod test can be used to target a specific bod range. Biochemical oxygen demand bod and chemical oxygen demand pdf. Quality of a given water sample depends on some variable factors. Innovox analyzer data and the actual cod measurement comparison chart. Bod biochemical oxygen demand is supposed to measure the amount of food or organic carbons that bacteria can oxidize. The aquatic organisms depend on the oxygen present in water or dissolved oxygen do for their respiratory needs. Characteristics of greywater from different sources within. Other related analytical values are biochemical oxygen demand bod, total organic carbon toc, and total oxygen demand tod. Bod, cod, toc and tod sum parameters in environmental. Chemical oxygen demand cod is a measure of all oxygendemanding substances, including those not amenable to biological treatment, and these, too, are reduced through wastewater treatment.
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. Chemical oxygen demand cod is a measure of all oxygendemanding substances, including those not amenable to biological treatment, and. Cod is the amount of oxygen required for the oxidation of total organic matter in water. Solar radiation was more efficient than artificial uv to the cod removal.
This study investigated the physicochemical characteristics of greywater from different sources within 75 households in a community in durban, south africa. A rapid cod method for bod estimations is therefore highly desirable. 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. Difference between bod and cod definition, test method. Cod ratio of less than 1 are observed most of time. Biochemical oxygen demand encyclopedia of life support systems. The quality of greywater depends on the source from which it is drawn as well as the use to which this water. Bod5 is the amount of oxygen requiredconsumed after 5 days incubation and bod3 is the amount of oxygen after 3 days. This paper discusses the new rapid cod technology as well as the new pcbodcod duo, a completely automated dual platform system that can be used to analyze both cod and bod using one efficient system. Biochemical oxygen demand audit checklist bod and cbod based on nr 219 2004, nr 149 2008 and standard methods 5210 b 18th, 19th and 20th editions this checklist is for the aid of the department and the laboratory. 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. Nema contactor and starter specifications technical data.
Real time bod estimations by automated cod analysis using. Some of these carbon compounds can be oxidized further by biological or chemical processes, and the biochemical oxygen demand. Bod is the amount of oxygen consumed by decomposition of the sample during the incubation period. You can use this determine dilution ranges on new sample sites. This paper discusses the new rapid cod technology as well as the new pc bod cod duo, a completely automated dual platform system that can be used to analyze both cod and bod using one efficient system. Standardization of bod 5 cod ratio as a biological. When you look at water in a lake the one thing you dont see is oxygen. In environmental chemistry, the chemical oxygen demand cod is an indicative measure of the amount of oxygen that can be consumed by reactions in a measured solution. The typical carbonaceousdemand curve a shows the oxidation of organic matter.
The chemical oxygen demand cod test is commonly used to indirectly measure the amount of organic compounds in water. It is only an audit guideline, it is not meant to establish regulatory standards or to dictate audit format. The main objective of the analysis was to investigate the relation between biochemical oxygen demand bod and chemical oxygen demand cod. The typical carbonaceousplusnitrogenousdemand curve b shows the additional oxidation of ammonia and. Jan 08, 2014 for the love of physics walter lewin may 16, 2011 duration. Wastewater treatment and discharge 2006 ipcc guidelines for national greenhouse gas inventories 6. Bod, cod, toc and tod sum parameters in environmental analysis. Standardization of bod 5 cod ratio as a biological stability. The most popular sum parameter in waste water ana more. 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. The bod 5 cod and the bod 5 cod sol indices are both consistent and can be both used as stability indices. There are two stages of decomposition involved in biological oxygen demand bod. Relationship between ts, tss and tds water chemistry. There is a significant observable trend noted in all values of bod.
Bod biochemical oxygen demand is the amount of oxygen consumed by biochemical reaction of microorganisms, protozoa and whatnot. Cod is the amount of oxygen required to chemically breakdown the pollutants whereas bod is the amount of oxygen required to do this biologically through microorganisms. If there is a large quantity of organic waste in the water supply, there will also be a lot of bacteria present working to decompose this waste. Mere treatment of ctmp effluent by traditional methods no longer fully meets todays needs. The bod value is most commonly expressed in milligrams of oxygen consumed per litre of sample during 5 days. Organics 2 university of georgia cooperative extension circular 922. Despite its limitations, it remains the most widely documented and one of the simplest ways to calculate a detection limit. Determination of biological oxygen demand bod in waste. Bod incubator biooxygen demand are used to maintain temperature for test tissue culture growth, storage of bacterial cultures and incubation where high degree of constant temperature accuracy is required.
Enter bod or cod values into the correlation tool spreadsheet bod or cod mgl column upon receiving the lab results. In this case, the demand for oxygen will be high due to all the bacteria so the bod level will be. After 5 days, the dissolved oxygen content had dropped to 2. Biochemical oxygen demand bod is the amount of dissolved oxygen needed i. Cod value is always greater than the bod value of a particular water body.
A conventional septic tank removes about 4050% bod 5 and 5070% ss laak, 1986. At 20c, the daily degradation capacity is 20,6 % of the relevant residual bod ha b e c ktr o p f k e, 1992 which means that, in ideal conditions and with a total bod bod 20 of 100. Introduction bod, like cod, is not one definable particle. Estimating the concentration and biodegradability of. Absolute value of difference between the dups, divided by the average of the. Cod should always measure higher than toc and then bod. Some counties within the state of washington have chosen to identify residential wastewater septic tank effluent characteristics. On the other hand, the organic substances contained in ctmp effluent can be converted and utilized. Application of photofenton process for the treatment 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. The intent is to measure what affect the sample will have on oxygen available to living organisms in the waters into which the waste is discharged.
General discussion the organic carbon in water and wastewater is composed of a variety of organic compounds in various oxidation states. During the treatment the organic matter of the effluent was more oxidized than mineralized, showing a higher removal of cod than bod biochemical oxygen demand and toc total organic carbon, respectively. Almost all wastewater treatment plants are required to measure one of. Chemical oxygen demand cod vs biological oxygen demand. Cod is usually measured and the test is simple and easy to perform with the right equipment and can be done in 2. Correlation between biochemical oxygen demand and chemical. Between the bod 5 and bod 20 values, the following pattern applies. Cod often is used as a measurement of pollutants in wastewater and natural waters. Bod measures the oxygen demand for the decomposition of organic.
Nema contactor and starter specifications ac coil data auxiliary contacts nema a600 and p300 bulletin 595, 596 nema size operating volt amperes burden va heat dissipation w coil operating limits 60 hz coils inrush sealed 00 70 8 2. Introduction chemical oxygen demand cod and biological oxygen demand. There is a strong correlation between cod and bod, however cod. Pdf can be found in find, read and cite all the research you need on researchgate. Difference between bod and cod definition, test method and. 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. Since these organisms grow slowly, it may take some time before the nitrification re action starts. Bod measures the amount of oxygen required by the aerobic organisms. Heater element specifications for application on bulletin 1005006091200 line starters for bulletin 512, size 2, again refer to table 153. Dairy processing methods to reduce water use and liquid waste load, kstate.
Biological oxygen demand bod is a measure of the oxygen used by microorganisms to decompose this waste. Difference between bod and cod compare the difference. How are your cbods tips, tricks and troubleshooting denise l seman. What are the differences between chemical oxygen demand cod. Biochemical oxygen demand audit checklist bod and cbod. A variety of research has been conducted to characterize greywater generated from various sources in order to determine greywater quality friedler 2004. The study was undertaken to create an understanding of greywater quality from different sources within and between households.
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