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).
What is the unit of BOD and COD?
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. Hence, the value of COD is greater than BOD.
How COD is measured?
COD is measured via a laboratory assay in which a sample is incubated with a strong chemical oxidant for a specified time interval and at constant temperature (usually 2 h at 150°C). The most commonly used oxidant is potassium dichromate, which is used in combination with boiling sulphuric acid.
What is the unit of BOD?
BOD’s are generally expressed as milligrams of dissolved oxygen per liter, which is equivalent to parts per million, PPM. BOD levels can vary considerably. Pristine water sources may show a BOD of less than 2 mg/L of water.
Why COD is calculated?
Chemical oxygen demand (COD) is used to determine the quantity of pollution in water after wastewater treatment. The higher value of chemical oxygen demand indicates the higher organic pollution in the water sample. Only chemically digest able matter can be determined by the COD test.
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 is BOD and COD measured?
Testing for BOD involves incubating a sealed water sample at 20C for five days, followed by measuring the difference in oxygen content before and after incubation. COD measures how much DO is consumed by the oxidation of organic matter and inorganic compounds such as ammonia or nitrite under controlled conditions.
What do you mean by COD?
Cash on delivery (COD) is a type of transaction where the recipient pays for a good at the time of delivery rather than using credit. The terms and accepted forms of payment vary according to the payment provisions of the purchase agreement.
How is COD measured in the lab?
To establish the COD:BOD ratio for your wastewater, simply have both COD and BOD run on several wastewater samples. Divide the COD concentration by the BOD concentration for each sample and average the results.
What is a COD meter?
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.
Why do we measure BOD and COD?
Answer: Both COD and BOD test methods aim to give an indication of the amount of pollution in a water sample. 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 micro-organisms.
Which is better BOD or COD?
COD is normally higher than BOD because more organic compounds can be chemically oxidised than biologically oxidised. This includes chemicals toxic to biological life, which can make COD tests very useful when testing industrial sewage as they will not be captured by BOD testing.
What is COD in waste water?
5 Chemical oxygen demand (COD) The COD is the estimate of oxygen required for the portion of organic matter in wastewater that is subjected to oxidation and also the amount of oxygen consumed by organic matter from boiling acid potassium dichromate solution.
How do you calculate kg in COD?
BOD (or COD) load: Units: kg/day
This is simply done by multiplying the BOD in mg/l by the daily effluent volume in cubic metres (m3) and dividing the product by 1000.
What is a high COD value?
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 is a good COD level?
Influent COD in normal domestic sewage is therefore generally 600 – 900 mg/l and it is then treated to at least 75 -100 mg/l before discharge to minimise pollution potential.
How is BOD value calculated?
Calculate the volume of 1N sulfuric acid or sodium hydroxide to be added to neutralize the 1000 ml sample as follows: 1N sulfuric acid or sodium hydroxide required = (2.1 ml x 1000 ml)/50 ml = 2100/50 = 42 ml.
What is COD in energy?
COD, or “Commercial Operation Date”, is the day that the system becomes fully operational and can begin selling power under the terms of the PPA. Typically, SolRiver releases any remaining funding amount when the project meets the COD milestone.
How does COD work?
COD is used by senders who want to collect payment for merchandise and/or postage and fees when the item is delivered to the receiver. Sender pays postage plus fees at time of mailing. The mailer guarantees to pay any return postage, unless otherwise specified on the mail. Amount collected may not exceed $1,000.
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.
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