COD and BOD tests are important because they help in the determination of the amount of waste in wastewater. This is important because the organic content in wastewater needs to be reduced before the wastewater is discharged.
Why are COD and BOD measured together?
Measuring Oxygen Demanding Wastes, by chemical method is carried out by COD and using biological species as seed, it is carried out by BOD. As already known both are measure of Dissolved Oxygen (DO) required to oxidize dissolved organic pollutant in waste-water sample.
Why is measuring BOD important?
The BOD is an important parameter for assessing water quality. It deals with the amount of oxygen consumption (mg O2 L− 1) by aerobic biological organisms to oxidize organic compounds. Sewage with high BOD can cause a decrease in oxygen of receiving waters, which in turn can cause the death of some organism.
What are BOD and COD what is their importance and mention their differences?
Biochemical oxygen demand (BOD) is the amount of oxygen required by the microorganisms to break down the organic materials, whereas chemical oxygen demand (COD) is the amount of oxygen required to break down the organic material via oxidation.
Which is more important BOD or 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.
Why is BOD measured after 5 days?
BOD occurs in 2 general stages. While calculating the oxygen demand, the carbonaceous stage is taken into account. This stage is almost completed in 5 days, which means that most of the organic content of the sewage is oxidized under aerobic conditions in 5 days. Hence ,BOD for 5 days is calculated.
Why is COD important in water quality?
COD is a water quality measure used not only to determine the amount of biologically active substances such as bacteria but also biologically inactive organic matter in water [8]. It is an important and rapidly measured variable for characterizing water bodies, sewage, industrial wastes, and treatment plant effluents.
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.
What does BOD tell us about water quality?
Higher BOD indicates more oxygen is required, signifying lower water quality. Low BOD means less oxygen is being removed from water, so the water is usually more pure. Since cold water retains oxygen better than warmer water, DO is usually lower in summer months.
Why COD is higher than BOD in wastewater?
The COD test uses a chemical (potassium dichromate in a 50% sulfuric acid solution) that “oxidizes” both organic (predominate) and inorganic substances in a wastewater sample, which results in a higher COD concentration than BOD concentration for the same wastewater sample since only organic compounds are consumed
Why is COD value higher than BOD value in polluted water?
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.
Why is BOD test run in the dark?
The BOD test bottle is stoppered to ensure that the system is closed. b. Why is the test run in the dark (or in a black bottle)? The test run is done in the dark or in a black bottle to ensure there is no sunlight getting into the bottle.
What happens if BOD is high?
The greater the BOD, the more rapidly oxygen is depleted in the stream. This means less oxygen is available to higher forms of aquatic life. The consequences of high BOD are the same as those for low dissolved oxygen: aquatic organisms become stressed, suffocate, and die.
Why is BOD calculated?
The BOD test measures the strength of the wastewater by measuring the amount of oxygen used by the bacteria as they stabilize the organic matter under controlled conditions of time and temperature.
What is the principle of COD?
The principle behind the COD testing method is that, under acidic conditions, a strong oxidising agent will oxidise almost any organic compound to carbon dioxide. COD analysis will measure the equivalent amount of oxygen that is required to chemically oxidise organic compounds in water.
How is COD calculated *?
Chemical Oxygen Demand is determined by measuring the dissolved oxygen used during the chemical oxidation of organic matter in 3 hours.
What it means COD?
cash on delivery
cash on delivery, collect on delivery.
What is the full form of 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.
What is the limit of COD?
The chemical oxygen demand (COD) concentration in a treated effluent, if observed to be persistently greater than 250 mg/l before disposal to any receiving body (public sewer, land for irrigation, inland surface water and marine coastal areas), such industrial units are required to identify chemicals causing the same.
What chemical is used in COD?
potassium dichromate
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.
Justin Shelton is a professional cook. He’s been in the industry for over 10 years, and he loves nothing more than creating delicious dishes for others to enjoy. Justin has worked in some of the best kitchens in the country, and he’s always looking for new challenges and ways to improve his craft. When he’s not cooking, Justin enjoys spending time with his wife and son. He loves exploring new restaurants and trying out different cuisines.