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.
Is high BOD a good thing?
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 does high BOD indicate?
Biochemical oxygen demand or BOD is the oxygen required for microbial decomposition of a unit mass of organic remains. The degree of impurity of water due to organic matter is measured in terms of BOD. A higher BOD of a river indicates that water is highly polluted .
What does BOD test indicate?
BOD is a measure of the amount of oxygen required to remove waste organic matter from water in the process of decomposition by aerobic bacteria (those bacteria that live only in an environment containing oxygen). ... BOD is used, often in wastewater-treatment plants, as an index of the degree of organic pollution in water.
What is BOD What does it mean if a water body has high BOD?
Biological Oxygen Demand indicates the increase in presence of organic matter in the water body. High BOD indicates the great amount of organic matter . The dissolved oxygen in water is consumed by bacteria to decompose the organic matter of sewage or other discharges thereby depleting the oxygen of the water body.
Why is COD higher than BOD?
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.
How do you reduce BOD levels in wastewater?
- Focus on removing TSS from wastewater first. ...
- Get a properly sized EQ tank. ...
- Control the pH of the waste stream. ...
- Install a modern plate pack DAF made of stainless steel or plastic. ...
- Use a regenerative turbine air dissolution pump.
What is a good BOD level?
A BOD level of 1-2 ppm is considered very good. There will not be much organic waste present in the water supply. A water supply with a BOD level of 3-5 ppm is considered moderately clean.
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 BOD of drinking water?
The biological oxygen demand (BOD) is also called biochemical oxygen demand. The BOD refers to the amount of oxygen required for the biotic degradation of organic matter in bodies of water. ... To evaluate drinking water, the TOC – Total Organic Carbon is measured, instead of the biochemical oxygen demand.
What is BOD Toppr?
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.
Why is BOD done for 5 days?
The standard oxidation (or incubation) test period for BOD is 5 days at 20 degrees Celsius (°C) (BOD5). The BOD5 value has been used and reported for many applications, most commonly to indicate the effects of sewage and other organic wastes on dissolved oxygen in surface waters (see TECHNICAL NOTE).
What is BOD COD and do?
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.
In which water BOD is maximum?
Notes: BOD is 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, for running rivers, it would be minimum and for Untreated Municipal waste water it would be maximum.
Which level of BOD indicates that water is polluted?
BOD indicates the amount of putrescible organic matter present in water. Therefore, a low BOD is an indicator of good quality water, while a high BOD indicates polluted water. Dissolved oxygen (DO) is consumed by bacteria when large amounts of organic matter from sewage or other discharges are present in the water.
How do you test for BOD?
To test the biochemical oxygen demand (BOD), the water samples of interest are diluted with nutrient rich water (containing a phosphate buffer solution, a magnesium sulfate solution, a calcium chloride solution, and a ferric chloride solution) and seeded with a known amount of bacteria.
