BOD and COD can reduce the DO of lakes and rivers, and low concentrations can cause eutrophication and harm aquatic life. Municipal wastewater discharge and industrial processes can create water high in COD/BOD, requiring careful treatment before discharge to preserve the health of waterways.
How does BOD and COD affect water quality?
Like COD, biochemical oxygen demand (BOD) measurement can be used to estimate the amount of pollution in a water sample. COD describes the amount of oxygen required to chemically break down pollutants, while BOD indicates the amount of oxygen required to breakdown organic pollutants biologically with microorganisms.
How can we reduce BOD and COD in industrial 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.
What is BOD and COD why it is important to determine in waste water treatment?
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 BOD and COD write its importance in environmental studies?
BOD means Biochemical oxygen demand. The microorganisms use organic matter as a food source through oxidation which oxygen is consumed. COD, Chemical Oxygen Demand, is a measure of the total quantity of oxygen required to oxidize all organic material into carbon dioxide and water.
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 happens when 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.
What is BOD removal?
COD/BOD Removal From Water
The biochemical oxygen demand (BOD) represents the amount of dissolved oxygen (DO) consumed by biological organisms when they decompose organic matter in water. The chemical oxygen demand (COD) is the amount of oxygen consumed when the water sample is chemically oxidised.
Why is BOD important in water quality?
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.
How do you remove COD from water?
One way to reduce COD in water is to use coagulants and flocculants to bind sludge together. Once they are bound into big enough masses that they can be easily filtered out and deposited into a sedimentation tank for removal. This method does however rely on the use of chemicals, and requires high reoccurring cost.
Which is more important BOD or COD?
COD is always higher than BOD because chemical oxidation is easier than biological oxidation.
What does COD and BOD indicate?
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.
What is the significance of BOD COD ratio?
Results of the investigation revealed that BOD: COD ratio is a good indicator for pollution measurement in river. It can be used as an indicator to predict the relationship of BOD and COD in the river. It is also found to be reliable and useful indicator to relate organic matter content in the river water.
What are the advantages and disadvantages of the COD test compared to BOD?
The COD test has the advantage of not being subject to interference from toxic materials, as well as requiring only two or three hours for test completion, as opposed to five days for the BOD test.
What is COD and its significance?
2)COD(chemical oxygen demand)- It is defined as the amount of oxygen required by organic matter in sample water for its oxidation by strong oxidizing agents (K2Cr2O7) in the hot conditions. It is a measure of both the biologically oxidisable & biologically inert organic matter.
What are the limitations of BOD test?
Limitations Of Test
The method takes five days to perform and uses a discrete sample. The test has poor reproducibility and toxic chemicals can inhibit measurement. Short-term BOD determinations magnify errors and still require relatively long sample periods. The test is not suited for on-line, continuous measurement.
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
What is BOD and COD limit?
According to standards of Central Pollution Control Board, permissible value of BOD is 30 mg/l and COD is 250 mg/l.
Why is COD high 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 does BOD tell us about water quality?
Nitrogen and Water
A small amount, but it is essential for life in the water. Biological oxygen demand (BOD) generally represents how much oxygen is needed to break down organic matter in water.
Is high BOD good for water quality?
Higher BOD indicates more oxygen is required, which is less for oxygen-demanding species to feed on, and signifies lower water quality. Inversely, low BOD means less oxygen is being removed from water, so water is generally purer.
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