What are the 4 types of BOD?

BOD technically stands for Biological Oxygen Demand BOD5 means the test has been run for 5 days. C-BOD means only the Carbonaceous Biochemical Oxygen Demand N-BOD means Nitrogenous Biochemical Oxygen Demand BOD5 typically includes C-BOD and N-BOD unless one or the other is inhibited.

What is the difference between BOD and ultimate BOD?

Generally, BOD is standardized by the measurement of oxygen consumption in 5 days (BOD5). But, determination of the ultimate biochemical oxygen demand (BODu), which is taken 28 days and the reaction rate constant (k) are necessary to understand the organic strength of the wastewater.

What are good BOD levels?

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 is the normal BOD?

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.

What is the difference between BOD5 and COD?

What's the difference between BOD5 and COD? COD or “Chemical Oxygen Demand” measures the quantity of oxygen required to degrade through oxidation all the organic and inorganic matter. But just to recap, BOD5 measures only the consumption of oxygen by micro-organisms, i.e. biodegradable pollution.

BOD (biological oxygen demand) - The water quality indicator

Why COD is preferred over BOD?

COD is preferred over BOD because COD can be found in a few minutes whereas BOD requires at last 5 days.

Which is faster BOD or COD?

COD is always higher than BOD because chemical oxidation is easier than biological oxidation.

What causes high BOD?

High biochemical oxygen demand can be caused by: high levels of organic pollution, caused usually by poorly treated wastewater; high nitrate levels, which trigger high plant growth.

How do you analyze BOD?

BOD measurement requires taking two samples at each site. One is tested immediately for dissolved oxygen, and the second is incubated in the dark at 20 C for 5 days and then tested for the amount of dissolved oxygen remaining.

What BOD level is moderately clean?

A water supply with a BOD level of 3-5 ppm is considered moderately clean. In water with a BOD level of 6-9 ppm, the water is considered somewhat polluted because there is usually organic matter present and bacteria are decomposing this waste.

How do you remove BOD from wastewater?

Three common BOD reduction methods for wastewater treatment are:
  1. Wastewater clarification.
  2. Wastewater separation (Coagulation & Flocculation)
  3. Anaerobic microbial decomposition.

What is BOD limit in wastewater?

As per the World Health Organisation, a limit of less than 5.0 mg/l is ideal for water bodies. At this limit BOD will not cause any harmful impacts on the human body, wastewater sewage must have BOD around 80 ppm and COD 200 ppm for discharge.

Are there different levels of BOD?

BOD values are usually reported in either ppm values or in mg/L values. Unpolluted rivers typically have a BOD below 1 mg/L. Moderately polluted rivers vary between 2 to 8 mg/L. Untreated sewage averages between 200 and 600 mg/L while efficiently treated municipal sewage would be 20 mg/L or less.

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.

What happens if BOD is high?

Effect of High BOD on the Aquatic Ecosystem

The oxygen used by aquatic organisms for respiration and metabolism is significantly reduced by the microbes for breaking down of organic waste. This results in the death of fishes and aquatic plants and complete disruption in the aquatic ecosystem.

Does ultimate BOD change with temperature?

Concept: Ultimate Biological Oxygen Demand: It is the amount of biodegradable organic matter present in the sewage sample. At any temperature the amount of organic matter present does not change, so the ultimate BOD will remain the same at any temperature.

What is the indicator used in BOD?

The BOD value is most commonly expressed in milligrams of oxygen consumed per liter of sample during a prescribed period of incubation at 20°C and is often used as an indicator of the degree of organic pollution of water.

Why do we measure BOD?

The amount of BOD in water is a measure of the amount of organic material present in water, in terms of how many oxygen will be required to break it down biologically. Clean water would have BOD value less than 5 ppm whereas highly polluted water has BOD value 17 ppm or more.

What is BOD and how is it measured?

The BOD test is a bioassay technique involving the measurement of oxygen consumed by the bacteria while stabilizing the organic matter in the waste as they would normally do in nature but under normal laboratory conditions. By convention, the test is conducted for a period of 5 days at 20°C (68°F).

Is low or high BOD better?

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.

Who increases BOD water?

The biological oxygen demand(BOD) increases with increase in aquatic organisms.

How do you measure BOD in water?

Measuring biochemical oxygen demand requires taking two measurements. One is measured immediately for dissolved oxygen (initial), and the second is incubated in the lab for 5 days and then tested for the amount of dissolved oxygen remaining (final).

What is the ratio of COD to 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.

How do you test COD in wastewater?

To establish the COD:BOD ratio for your wastewater, simply have both COD and BOD run on several wastewater samples. Divide the COD concentration by the BOD concentration for each sample and average the results.

How do you convert BOD to COD?

Typically, the average BOD result is divided by the average COD result to find a "conversion factor" between the two parameters. One would then multiply their COD results by this factor to estimate BOD. COD values are almost always higher than BOD values for the same sample.