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 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. Organic matter nonbiodegradable and biodegradable toc, cod, do, bod, bodu and serial bod dr. Chapter 4 anaerobic sewage treatment using uasb reactors. Pdf determination of bod, cod, do and other physico. Mihelcic encyclopedia of life support systems eolss 2. 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. Biological oxygen demand is an important water quality parameter because it greatly influences the concentration of do that will be in the water. 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. National field manual for the collection of waterquality. Difference between bod and cod compare the difference.
Biochemical oxygen demand bod, chemical oxygen demand cod, and by determination of total organic carbon toc. Correlation between bod, cod and toc 191 exponential equation is fitted for the observed behaviour of bod as a function of cod. Ultimate bod ubod the ultimate biochemical oxygen demand ubod is a parameter that quantifies the. Bod refers to the biochemical oxygen demand and cod is the chemical oxygen demand. Also, it can be categorized in several ways such as biological, physical and. Biochemical oxygen demand bod waste water engineering apsed. The qvalue curve for bod used in calculating a water quality index2 illustrates the relationship between bod and water qualitythe higher. Solid retention time srt or mean cell residence time. Codbod ratio is generally high for industrial waste than domestic etc waste. Cod refers to total cod of the raw wastewater van haandel and lettinga 1994. Difference between bod and cod definition, test method. It is the rate at which organisms use the oxygen in wastewater while digesting organic matter. These test procedures and relevance of these tests are discussed below. Cod is chemical oxygen demand, measured by strong oxidation with dichromate, which oxidizes all organic compounds.
Cod, nutrients, nitrogen and phosphorus present in waste water different salts and different ions, cations and anions. This ratio varies a lot for domestic sewage as well for septic sewage and may decrease alarmingly with time for. Enrol today in our site and get access to our study package comprising of video lectures, study material, practice questions and test. It is a variation of the bod test that measures the oxygen demand due to carbon based. Carbon toc, theoretical oxygen demand thod, nutrients. 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. In this case, the demand for oxygen will be high due to all the bacteria so the bod level will be. After fermentation remains waste from bottom of distillation columns, termed stillage. Toc test will not be conducted but the procedures will be demonstrated to the students. Biochemical oxygen demand bod biological oxygen demand.
Chemical oxygen demand cod vs biological oxygen demand bod. Bod is a measure of, the amount of oxygen required for the bacteria to degrade the organic components present in water waste water. Biological oxygen demand bod is the amount of oxygen. Determination of biological oxygen demand bod in waste. Biological oxygen demand bod is a measure of the oxygen used by microorganisms to decompose this waste. Bodcod bod is biodegradable organics during 5 days at 20 degr. The chemical oxygen demand cod test is commonly used to indirectly measure the amount of organic compounds in water. Have covered the theory of biochemical oxygen demand including the carbonaceous and nitrogenous demand, dilution method to. Lecture 5 water and wastewater characteristics youtube. The national field manual for the collection of waterquality data nfm is an online report with separately published chapters that provides the protocols and guidelines by which u. Here in such cases you know you can see this bod, cbod, nbod that we have explained. Determine bod5 of wastewater and compute the ultimate bod. Biochemical oxygen demand bod waste water engineering.
In whole world, cane molasses base distilleries are included under one of the polluting industries in concern to water pollution. Unesco eolss sample chapters environmental and ecological chemistry vol. The cod what it means theoretical oxygen demand and total. Biological oxygen demand measures the amount of oxygen used by microorganisms in the oxidation of organic matter. 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. The allocation of samples to each batch is given in table 1. Correlation between bod, cod and toc industrial pollution. Biochemical oxygen demand bod and chemical oxygen demand pdf 1. Chemical oxygen demand cod vs biological oxygen demand.
Reddy thapar university patiala punjab 147 004 india 2. Fundamentals of environmental pollution and control prof. What is biological oxygen demand and how does it affect. Treatment performance of the first fullscale uasb plants treating municipal sewage. Chemical oxygen demand cod is the amount of oxygen consumed by the organic compounds and inorganic matter which were oxidized in waste. Biological oxygen demand bod is the rate at which organisms use the. The fm can be varied by varying mlvss concentration in the aeration tank. Hence, the cod bod ratio for the sewage is around 1. Geological survey personnel obtain the data used to assess the quality of the nations surfacewater and groundwater resources.
Most applications of cod determine the amount of organic pollutants found in surface water e. The bod test measures the oxygen demand due to both carbon and nitrogen based compounds. None of the alternatives provide a better assessment of the bioavailability of a waste like the bod test. Measurement of organic matter concentration organic matter in wastewater is heterogeneous suspended colloidal and dissolved organic matter. So, that way we can have very particular values of bod and cod depending on the. Course on industrial biotechnology by professor debabrata. Understanding dilution and seeding procedures in bod test.