COD is often used as a measurement of pollutants in water, wastewater, and aqueous hazardous wastes. One application of the COD test is to measure soluble COD in wastewater, since characterization of total COD in wastewater is critical for accurate modeling of biotransformation in wastewater treatment processes.
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What is COD analysis?
Chemical Oxygen Demand (COD) analysis is a measurement of the oxygen-depletion capacity of a water sample contaminated with organic waste matter. Specifically, it measures the equivalent amount of oxygen required to chemically oxidize organic compounds in water.
What are the importance and applications of COD in our day to day life explain why COD can be used as a measure of water pollution by organic compounds?
The chemical oxygen demand (COD) is a measure of water and wastewater quality. The COD test is often used to monitor water treatment plant efficiency. This test is based on the fact that a strong oxidizing agent, under acidic conditions, can fully oxidize almost any organic compound to carbon dioxide.
Why is COD so important?
In wastewater treatment, the Chemical Oxygen Demand (COD) is an important measurement for the amount of oxygen that is required to break down pollutants (organic substances) in water. The chemical oxygen demand can be measured using different methods, direct or indirect.
Which reagent is used for COD analysis?
potassium dichromate
The most general COD determination uses potassium dichromate (K2Cr2O7) in excess in an acidic medium with the aid of silver sulfate (Ag2SO4) as a catalyst, and mercuric sulfate (HgSO4) added to remove interference of chlorides.
How do you do a COD analysis?
Method summary
An aliquot of the sample is digested for two hours at 150°C in the presence of dichromate and sulfuric acid. The resulting solution is titrated to a colored endpoint with ferroin indicator or read on a spectrophotometer at an appropriate wavelength.
What does the COD test measure?
1.2 Chemical Oxygen Demand. COD is an indicative measure of the amount of oxygen that can be consumed by reactions in a measured solution. It is commonly expressed in mass of oxygen consumed over volume of solution, which in SI units is milligrams per liter (mg/L).
Why COD is important in water treatment?
Chemical oxygen demand (COD) is the amount of dissolved oxygen that must be present in water to oxidize chemical organic materials, like petroleum. COD is used to gauge the short-term impact wastewater effluents will have on the oxygen levels of receiving waters.
What is the importance of measuring COD and SAC at a wastewater treatment plant?
TOC, COD and SAC analyzers are used to assess the organic load of surface water, municipal wastewater and industrial wastewater. They measure total organic carbon, chemical oxygen demand and spectral absorption coefficient. Measurement in the outlet ensures compliance with regulatory requirements.
What is the importance of determining COD and BOD?
Biological Oxygen Demand (BOD) and Chemical Oxygen Demand (COD) are two of the most important parameters to characterise (measure the degree of pollution) of wastewater. BOD, the biological demand for oxygen a source of water has, is the amount of oxygen used by microorganisms to break down organic substances.
What is COD business?
Cash on delivery, or collect on delivery (COD), is a method of collecting payment that requires customers to pay for goods at the time of delivery. Companies that manufacture and distribute goods deliver products to potentially thousands of customers every day.
What is COD in shipping?
Collect on Delivery (C.O.D.)
What is shirako made out of?
Shirako, called milt in English, are the seminal vessels typically harvested from cod, and sometimes from anglerfish, salmon, squid and pufferfish. The harvested sperm sacs are tube-like in shape, usually white or light pink in color, with the layout and consistency of brains.
Why Sulphuric acid is used in COD?
Chemical Oxygen Demand (COD) 1% Silver Sulphate in Sulphuric Acid (conc.) provides the primary and secondary digestion catalysts for oxidation of carbon during chemical oxidation.
Which indicator is used in COD estimation?
test is. Concept: Chemical Oxygen Demand (COD) test is used to measure the content of organic matter of waste water, both biodegradable and non-biodegradable.
What is the basis for the COD test?
The basis for the COD test is that nearly all organic compounds can be fully oxidized to carbon dioxide with a strong oxidizing agent under acidic conditions. The amount of oxidized agent need to completely oxidize the organic material is then compared to the equivalent amount of oxygen.
What happens if COD is high?
Higher COD levels mean a greater amount of oxidizable organic material in the sample, which will reduce dissolved oxygen (DO) levels. A reduction in DO can lead to anaerobic conditions, which is deleterious to higher aquatic life forms.
What causes high COD in wastewater?
COD increases as the concentration of organic material increases. It also increases if inorganic compounds susceptible to oxidation by the oxidant (typically dichromate) are present. Water with high COD typically contains high levels of decaying plant matter, human waste, or industrial effluent.
What is the value of COD?
The COD value indicates the amount of oxygen which is needed for the oxidation of all organic substances in water in mg/l or g/m3. The COD (Chemical Oxygen Demand) is closely related to the laboratory standard method named Dichromate-Method.
How do you reduce COD in wastewater?
You can reduce COD and BOD by adding hydrogen peroxide to the wastewater solution. The hydrogen peroxide will chemically attack the organics in the wastewater, degrading them and reducing the measured COD and BOD.
Which is higher BOD or COD?
COD is always higher than BOD because chemical oxidation is easier than biological oxidation.
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