To evaluate the cod measurement technique using a standard sample. Iso 6060 water quality determination of the chemical oxygen demand. Potentiometric measurement of chemical oxygen demand article pdf available in water s. Understand the chemistry of do measurement by winkler method. Biochemical oxygen demand and chemical oxygen demand. Abstract measurement of the cod of a spent caustic solution. 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 biochemical oxygen demand results from the respiratory processes of microorganisms and microorganisms are alive. There are three widely used indices for assessing the oxygen demand of organic pollutants in an aqueous system. Chemical oxygen demand cod was measured directly with a simple electrochemical method using a borondoped diamond bdd electrode. Afterwards, the electrode is cleaned automatically by means of the membrane pumps built into the sample changer and the reaction vessel is emptied. Because of its unique chemical properties, the dichromate ion cr2o7. Pdf determination of low chemical oxygen demand using.
If there is a large quantity of organic waste in the water supply, there will also be a lot of. Biological oxygen demand bod5 is the amount of oxygen. Milliporesigma is a global leader in the life science industry and has produced test. Nearinfrared spectrometry, wastewater, biological oxygen demand, chemical oxygen demand.
Because oxygen demand is not a pollutant, it poses no direct threat to fish or other life. Determination of low chemical oxygen demand using potentiometry and a modified gran function richard e loewenthal1, dragoljub bilanovic2, thebe m thebe1 and michal green2 department of. The quantity of oxidant consumed is expressed in terms of its. The term also refers to a chemical procedure for determining this amount. Uncertainty of chemical oxygen demand determination in. Jun 18, 20 biochemical oxygen demand measures the quantity of oxygen consumed by microorganisms during the decomposition of organic matter. Chloride interference is an important problem of cod measurement for wastewaters containing low organic matter and high chloride concentrations. Chemical oxygen demand testing is typically performed using a strong oxidizing chemical. Mihelcic encyclopedia of life support systems eolss summary. Keywords chemical oxygen demand, spent caustic and potentiometric determination i. It is expressed as ppm or milligrams per liter mgl of oxygen. Standard test methods for chemical oxygen demand dichromate. Biological oxygen demand bod is a measure of the oxygen used by microorganisms to decompose this waste.
Dissolved oxygen can also be determined with precision using oxygen sensitive electrodes. Determination of low chemical oxygen demand using potentiometry and a modified gran function richard e loewenthal1, dragoljub bilanovic2, thebe m thebe1 and michal green2 department of civil engineering, university of cape town, rondebosch 7700, south africa 2 the lowdermilk faculty of agricultural engineering, technion israel institute of technology, technion city, haifa 32000, israel. 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. The analysis for do is a key test in water pollution and waste treatment process control. Estimation of chemical oxygen demand in wastewater using. Other than that, they are really the identical process.
Pdf potentiometric measurement of chemical oxygen demand. Chemical oxygen demand titrimetric, midlevel epa 410. There are several methods for determination of chemical oxygen demand but the wet chemical method dichromate method is the most common method. Biochemical oxygen demand bod and chemical oxygen demand pdf. In essence a cod test determines the amount of carbon based materials by measuring the. The quickcod ultra from lar process analysers ag is an online measurement system for the measurement of chemical oxygen demand cod using thermal combustion, giving a result within. The quickcod ultra from lar process analysers ag is an online measurement system for the measurement of chemical oxygen demand cod using thermal combustion, giving a result within minutes, even in difficult sample matrices. The titration is carried out directly in the reaction vessel on the rack. Chemical oxygen demand cod is the amount of oxygen consumed by the organic compounds and inorganic matter which were oxidized in water. Biochemical oxygen demand bod testing and measurement in. Simultaneous determination of chemical oxygen demand cod.
Organic matter is oxidized into carbon dioxide and water in an acidic condition. Chemical oxygen demand cod the chemical oxygen demand, or cod, is a measurement of the amount of material that can be oxidized combined with oxygen in the presence of a strong chemical oxidizing agent. Biochemical oxygen demand measures the quantity of oxygen consumed by microorganisms during the decomposition of organic matter. 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. The quickcodultra is suitable for almost every cod measurement in sewage treatment and industrial waste water applications. Modules in which prior training is required to complete this module successfully and other available, related modules in this category are listed in the table below.
Determination of chemical oxygen demand of water hard and. Quickcod online cod monitor to measure chemical oxygen. 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. Determination of chemical oxygen demand in spent caustic. A novel spectrophotometric assay method using homemade reagents that can be used to determine the chemical oxygen demand cod in real wastewater is described. Odell inorganic chemistry branch chemistry research division. May 23, 2010 chemical oxygen demand cod is used as a discharge standard parameter in wastewater treatment plant design, environmental modelling and many other applications. Trivalent manganese as an environmentally friendly oxidizing. Chemical oxygen demand cod is the amount of oxygen consumed by the. It can, however, pose an indirect threat to living organisms by reducing the level of dissolved oxygen. In this case, the demand for oxygen will be high due to all the bacteria so the bod level will be. A spectrophotometric method for determination of chemical. Simultaneous determination of chemical oxygen demand. Abstract the measurement uncertainty of the result of chemical oxygen demand determination in wastewater was evaluated.
Determination of chemical oxygen demand in spent caustic by. In addition, interference from components in the samples may affect the test results. This oxygen transaction is the source of the tests name, chemical oxygen demand. The chemical oxygen demand cod indicates the amount of oxygen which is needed for the oxidation of all organic substances in water and is thus an important indicator for water analysis. 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. Measuring chemical oxygen demand in water treatment. 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. Since the degradation of organic compounds requires oxygen, their. Determination of amount of chemical oxygen demand cod in water. Since the degradation of organic compounds requires oxygen, their concentrations can be estimated by the amount of required oxygen. To determine the chemical oxygen demand of various samples of water.
Quickcod online cod monitor to measure chemical oxygen demand. Potentiometric measurement of chemical oxygen demand. Finding excessive levels of one or more of these parameters can serve as an early warning of potential pollution problems. Such electrodes require frequent standardization with waters containing. Direct determination of chemical oxygen demand by anodic. Toc analysis is utilized to assess soluble organic compounds, but does not express the oxidizable fraction of organic matter, which is. In this paper, we established how the biocatalytic activities of bacteria on organic matter substrates produced some electrons with the associated removal of some water pollution parameters. Oct 06, 2017 chemical oxygen demand titrimetric, midlevel epa 410.
Modules in which prior training is required to complete this module successfully and other available, related. This module deals with significance and chemistry of chemical oxygen demand measurement. It is considered in the planning and controlling of treatment, as well as assessing its efficiency, thus forming the basis for the calculation of waste water. The concentration of dissolved oxygen can be readily, and accurately, measured by the method originally developed by winkler in 1888 ber. Biochemical oxygen demand bod, chemical oxygen demand cod to the tune of 77. Chemical oxygen demand titrimetric, high level for saline waters analyte. Typically this measurement is used to monitor and control oxygen consuming pollutants, both inorganic and organic, in domestic and industrial wastewaters. The cod value depends on oxidizing agent, ph, temperature, and period of time. Finding excessive levels of one or more of these parameters can serve as. In essence a cod test determines the amount of carbon based materials by measuring the amount of oxygen the sample will react with. Automatic system for potentiometric titration of cod samples in series up to 21 samples. Oxygen demand is an environmentally important parameter which reflects the degree of organic pollution in water. Estimation of chemical oxygen demand in wastewater using uv.
Introduction the organic matter present in sewage can be measured in number of ways. Sca, blue book 215 the determination of chemical oxygen demand in waters and effluents. A method for the simultaneous determination of chemical oxygen demand cod and inorganic carbon by spectrophotometric and potentiometric ph detection, respectively, is described. The homemade reagents were used instead of the american hach reagents. The quantity of oxidant consumed is expressed in terms of its oxygen equivalence. Jan, 2017 the cod value depends on oxidizing agent, ph, temperature, and period of time.
Some laboratory test methods can be time consuming and expose technicians to toxic chemicals. The major sources of uncertainty of the result of measurement were. A new approach for chemical oxygen demand cod measurement. Chemical oxigen demand 11 of 8 interpretation of results the cod of the given sample of water 288 mgl. While designing a training course, the relationship between this module and the others, would. Because of its unique chemical properties, the dichromate ion cr 2 o 7 is the. Chemical oxygen demand cod is used as a discharge standard parameter in wastewater treatment plant design, environmental modelling and many other applications. The major sources of uncertainty of the result of measurement were identified as the purity of reagents, volumetric operations, gravimetric operations, bias, and the repeatability of the method. There are three widelyused methods of measuring oxygen demand.
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