If the BOD/COD ratio for untreated wastewater is 0.5 or greater, the waste is considered to be easily treatable by biological means. If the ratio is below about 0.3, either the waste may have some toxic components or acclimated microoorganisms may be required in its stabilization.
What is the ratio of BOD to COD for a given wastewater sample?
For example, food processing wastewater will generally have a COD:BOD ratio of ~2:1, while textile wastewater that can contain dyes will often have a much higher COD:BOD ratio of ~5:1. To establish the COD:BOD ratio for your wastewater, simply have both COD and BOD run on several wastewater samples.
What is the ratio between COD and BOD?
BOD : COD (Chemical oxygen demand) ratio using the formulated seed comes in the range of 0.7-0.8 whereas that using BODSEED comes in the ratio of 0.5-0.6. The ultimate BOD (UBOD) was also performed by exceeding the 3-day dilution BOD test.
What does a low BOD COD ratio mean?
TTK University of Applied Sciences. What the BOD to COD ratio shows is the measure of wastewater susceptibility to biodegradation: the lower is the ratio, the more refractory matter it contains. In your case, the water is not really biodegradable as it is.
What is the ratio of COD BOD for fresh water?
For fresher water, as both BOD and COD should be negligible, hence the ratio can be equal to 1.
What is the ratio of BOD COD in untreated waste Mcq?
0.3-0.8
Explanation: The ratio of BOD/COD is 0.3-0.8 in untreated waste.
Which of the following shows the correct relationship BOD and COD?
The only relation between COD & BOD is – COD > BOD. For most industrial process waste water, community sewage, drains and even some hetrogeneous sources, COD/BOD ratio has been found to be in a defined range and hence, COD result gives more or less BOD value range for such identifiable waste water.
How do you treat water with low BOD COD ratio?
Increasing biodegradability of a low BOD/COD ratio could be carried out by addition of organic chemicals which have high BOD/COD ratio such as glucose, methanol and acetic acid. Or, mixing the low biodegradable wastewater with high biodegradable wastewater would increase biodegradability of the low BOD/COD ratio.
What is the permissible limit of BOD in wastewater?
The Significance of BOD in Wastewater Treatment
BOD is listed as a conventional pollutant under the U.S. Clean Water Act. Typical maximum values range from 10 mg/L for direct environmental disposal and 300 mg/L for disposal to sewer systems.
What does high COD to BOD ratio of an organic pollutant represents?
A high COD to BOD ratio means that the organic pollutant has very less organic matter which can be oxidized by the pollutant. This ratio is generally greater than 1 but can be equal to 1 if the sample has only biodegradable organics.
How is the value of COD compared to BOD Mcq?
COD value is always greater than BOD for every wastewater sample.
What kind of dilution water is used for high BOD content wastewater in the bod5 test?
The diluted sample used to determine BOD must have a pH between 6.5 and 7.5. For municipal sewage or effluent, the pH range is generally between 5 – 9, but the buffering capacity of the phosphate buffer will often bring the pH of the diluted sample between 6.5 and 7.5.
Why COD and BOD ratio is important?
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 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 causes high BOD in wastewater?
Sources: BOD represents the amount of organic matter in a water supply; therefore, it increases when decaying plants, human or animal waste, and other organic compounds are added to water.
What is BOD and COD and what is the permissible limit?
According to WHO for drinking water BOD limit is less than BOD around 80 ppm and COD 200 ppm for discharge in see”.
What is the permissible limit of BOD & COD in waste water according to the Central Pollution Control Board?
The Central Pollution Control Board has prescribed the limit of BOD for the discharge of industrial and municipal waste in order to regulate the water pollution and for efficient water treatment, and it is .
What is the minimum value of BOD in polluted water?
Clean water has BOD value less than 5 ppm. Polluted water has BOD value higher than 10 ppm.
How do you measure BOD and COD in water?
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.
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