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 term also refers to a chemical procedure for determining this amount. Mar 27, 2012 a secondary effluent has a total bod of 45 mgl. In contrast, the patterns for nonurban areas were rather irregular with no common feature observed for the individual.
The method consists of filling an airtight bottle with a sample. Chemical oxygen demand cod vs biological oxygen demand bod. Biochemical oxygen demand rate constant 1 is dependent on temperature, it can be calculated as, 1 1 20. Determination of biological oxygen demand bod in waste. The determination of chemical oxygen demand in waters and. Mar 24, 2010 biochemical oxygen demand bod and chemical oxygen demand cod, indirect indicators of organic matters, are representative parameters for sewer water quality. The bod5 value of 1747 mg l 1, cod a value of 3595 m l 1 and journal of applied biotechnology issn 23270640 2020 bodcod ratio of 0. The bod5 value of 1747 mg l 1, cod a value of 3595 m l 1 and journal of applied biotechnology issn 23270640 2020 bod cod ratio of 0. Cod, another nonspecific measure of pollution often used to supplement bod. Sample calculation for bod sample calculation for bod determine the 5.
Formula sheet for all wastewater operator exams revised 815. Correlation between bod, cod and toc industrial pollution. Experimental procedure the treated effluent was tested for bod, cod and toc. This method has been widely adopted as a standard, based on historical use and convenience, since it is usually impractical to wait 20 or more days for the outcome of the test. Organics in wastewater may be refractory organics in wastewater are degradable. 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. It is the broad measure of the strength of the organic matter in a waste stream. 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. Cod is useful in terms of water quality by providing a metric to determine the effect an effluent will have on the. The siphon hose must be made of surgical gum latex rubber, polypropylene or polyethylene to avoid introducing bod into the dilution water. Toc or total organic carbon is the measurement of organic carbons.
This requires historical data of bod and cod measurements taken over a period of time. Difference between bod and cod definition, test method and. Bod, cod, and toc may 10, 2020 the organic strength of wastewater is measured in three ways. Most applications of cod determine the amount of organic pollutants found in surface water e. Biological oxygen demand is an important water quality parameter because it greatly influences. Three samples are used for this example, but 3 samples are too few to calculate an accurate ratio. Carefully fill a bod bottle with sample water without making air bubbles. Principal wastewater constituents treatment methods for. Cod is useful in terms of water quality by providing a metric to determine the effect an effluent will have on the receiving body, much like biochemical oxygen demand bod. Biological oxygen demand bod is a measure of the oxygen used by microorganisms to decompose this waste. 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. What would be the bod 8 if the test were run at 15oc.
Jun 07, 2017 difference between bod and cod definition. The bod 5 of a wastewater is determined to be 150 mgl at 20oc. Typical values for the ratio of bodcod for untreated municipal wastewater are in the range from 0. High bodcod is indirect indicator of the organic content. 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 bod bod measures the amount of oxygen required by the aerobic organisms to decompose organic matter and cod measures the oxygen required to decompose organic and inorganic constituents present in the wastewater by chemical reaction. The siphon hose must be made of surgical gum latex rubber, polypropylene or polyethylene to avoid. For unknown samples, check the ph of the dilution which uses the most sample to confirm that the dilutions lie in the proper ph range. Typically, the average bod result is divided by the average cod result to find a conversion factor between the two parameters. 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. 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. Add 1 2 glass beads to avoid the bumping during heating. 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.
Waste is considered to be easily treatable by biological means if bodcod ratio is 0. Cod is the amount of oxygen required for the oxidation of total organic matter in water. The application of phytoreduction by saccharum spontaneum to treat municipal wastewater also may decrease the concentration of cod, bod, and tss in the percentage of 56. Calculate the 5day bod of a domestic wastewater based on the following data. The hach wims bod manager utilizes the following calculations to perform the bod method. Correlation between biochemical oxygen demand and chemical.
High bod cod is indirect indicator of the organic content. Example calculations evaluation for fine bubble aeration. 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. Estimation of biological oxygen demand and chemical. Removal of municipal wastewater bod, cod, and tss by. Cod or chemical oxygen demand is the total measurement of all chemicals in the water that can be oxidized.
The bod value is most commonly expressed in milligrams of oxygen consumed per litre of sample during 5 days. The chemical oxygen demand cod test is commonly used to indirectly measure the amount of organic compounds in water. Chemical oxygen demand an overview sciencedirect topics. As needed neutralize samples with 1n sulfuric acid or 1n sodium hydroxide.
Biochemical oxygen demand bod and chemical oxygen demand pdf. Determine 1day bod and ultimate first stage bod for a ww whose 5 day bod is 200mgl at 20. However, another substance in wastewater leads to inhibition of bacteria that. Biochemical oxygen demand bod biological oxygen demand. Methods c and d were used for samples with chemical oxygen demand cod values of up to 400 mg l1. Biochemical oxygen demand bod can be estimated from chemical oxygen demand cod measurements, if a correlation is established. Cod is a measure of total organic molecules dissolved in waste water, where as the concept of bod came after cities started dumping their waste water into the water bodies and this led to depletion of oxygen and then death of water bodies. However, it is very difficult to obtain continuous water quality data because of the scarcity of accessible space within the sewer systems and the necessity of separate laboratory. Organics 2 university of georgia cooperative extension circular 922. In this case, the demand for oxygen will be high due to all the bacteria so the bod level will be. Enter bod or cod values into the correlation tool spreadsheet bod or cod mgl column upon receiving the lab results.
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. Cod correlation provides operations, laboratory benefits. A bod5 test is run on this same secondary effluent at the same time using a nitrification inhibitor. Calculation of the effluent bscod below you can find the typical coefficients and data used to establish the basic design of a complete mix suspended growth biological sewage wastewater process. The two most common parameters used to recognize the composition of wastewater are the 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. Therefore i t is used to measure the amount of certain type of organic water pollution bod is calculated by keeping a sample of water containing a known amount of oxygen for five days at 20 c. For example, the organics in a wastewater sample represented by bod will also be represented in the.
Innovox analyzer data and the actual cod measurement comparison chart. The bottle is a specified size and filled to overflowing. Formula sheet for all wastewater operator exams revised. Biochemical oxygen demand bod is the amount of dissolved oxygen needed i. Biochemical oxygen demand encyclopedia of life support. Intially, the ph of the treated effluent sample was brought to 7. The typical range of bod 5 in domestic wastewater ranges from 100 to 300 mgl. The sample is incubated at constant temperature for five days.
Estimation of biological oxygen demand and chemical oxygen. Chemical oxygen demand cod vs biological oxygen demand. Calculating the effluent bod or bscod or a biological. Bod and cod in hindi biochemical oxygen demand and chemical oxygen demand duration. Add 2ml of manganese sulfate to the bod bottle carefully by inserting the pipette just below the surface of water. Wastewater treatment modeling acknowledgments glossary bibliography biographical sketches. Bod biochemical oxygen demand is supposed to measure the amount of food or organic carbons that bacteria can oxidize. Bod of a wastewater stream can be read out from the graphs showing fitted curves or from the generated equations. Bodcod bod is biodegradable organics during 5 days at 20 degr. Do not dilute the sample with the acid or base by more than 0.
Biochemical oxygen demand bod and chemical oxygen demand cod, indirect indicators of organic matters, are representative parameters for sewer water quality. Each bod bottle is filled by slowly adding sufficient dilution water so that the stopper can be inserted without leaving an air bubble but not so much that there is overflow. To use this calculator please fill in the input value data of your sewer wastewater and as a result some basic plant design and effluent bod data will. Wastewater treatment and discharge 2006 ipcc guidelines for national greenhouse gas inventories 6. May 10, 2020 bod, cod, and toc may 10, 2020 the organic strength of wastewater is measured in three ways. 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. So that you can avoid the formation of air bubbles. Bod is the amount of oxygen consumed by bacteria while decomposing organic matter under aerobic conditions.
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