What BOD means?
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.
Why is BOD value important in wastewater treatment?
Significance of BOD BOD finds its primary importance in sewage treatment plants. It gives the respiration rate of sewage, sludge, soil, garbage. It determines the rate of respiration in living beings. Measuring BOD gives the COD or Chemical Oxygen Demand of inorganic substances.
What causes BOD in wastewater?
Sources of BOD Sources of biological oxygen demand include leaves and woody debris; dead plants and animals; animal manure; effluents from pulp and paper mills, wastewater treatment plants, feedlots, and food-processing plants; failing septic systems; and urban storm water runoff.
What is BOD and why is it important?
Biochemical Oxygen Demand (BOD) 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. In STPs, BOD facilitates anaerobic processes but if there is large excess can lead to bacteria die.
What is the BOD of clean water?
Drinking water has a BOD level of 1 – 2 ppm. When the BOD value of water is in the range 3 – 5 ppm, the water is moderately clean. Polluted water has a BOD value in the range of 6 – 9 ppm. In polluted water, some organic waste is present.
How is BOD of sewage determined?
6.4 Mark the bottles as blank and sample. 6.5 Incubate one sample and one blank bottle at 20 °C for 5 days….Biological Oxygen Demand (BOD):
| Recommended sample volume for BOD determination | ||
|---|---|---|
| BOD range (mg/liter) | Sample volume (ml) | Dilution water (ml) |
| 11-30 | 100 | 200 |
| 31-70 | 50 | 250 |
How does BOD affect water quality?
The dissolved oxygen readings are usually in parts per million (ppm). 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.
What are the advantages of BOD?
The main advantages of this method compared to the dilution method are: simplicity: no dilution of sample required, no seeding, no blank sample. direct reading of BOD value. continuous display of BOD value at the current incubation time.
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.
What is BOD removal efficiency?
So, coming into the plant is 245 mg per liter of BOD and leaving there’s 22 mg per liter. We have a formula that says efficiency or removal efficiency equals what’s coming in minus what’s coming out then you divide that by what’s coming in and then we multiply by a 100 to convert the decimal to a percent.
What is the difference between BOD and COD in wastewater?
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. COD analysis on the other hand is a measurement of the oxygen-depletion capacity of a water sample contaminated with organic waste matter.
What is the value of BOD of good quality water?
BOD values range widely; generally, pristine waters have a value below 1 mg l−1, moderately polluted waters 2–8 mg l−1, and treated municipal sewage 20 mg l−1. Standards for the discharge of effluent from WWTPs have the range 20–30 mg l−1 and require a minimum flow in receiving waters to ensure sufficient dilution.
What causes high BOD in wastewater?
Different pollutants (as stated above) will cause this. A high BOD in water meaning that you have a water with a great amount of microrganisms, mainly aerobic bacteria. This fact is very common in areas contaminated with wastewater or effluents of twater reatment plants.
What does BOD stand for?
What Is Biological Oxygen Demand in Wastewater Treatment? Biochemical oxygen demand or biological oxygen demand (BOD) is a measure of the amount of Dissolved Oxygen (DO) required by aerobic microorganisms to decompose organic matter present in a sample of water at a certain temperature over a studied period.
What is BOD and do in water?
Biochemical Oxygen Demand or BOD, is the amount of oxygen needed by organisms to break down the organic material in wastewater. BOD in wastewater is the result of human waste, food waste and other organics which are sent to the sewers. It is normal for water to have some organics.