How is BOD used?

BOD (Biochemical Oxygen Demand) is primarily used in water quality management to measure organic pollution, indicating how much oxygen microorganisms consume breaking down waste in water, thus assessing water health, wastewater treatment plant efficiency, and the impact of discharges on aquatic life. Higher BOD means more pollution and less available oxygen for fish, while lower BOD signifies cleaner water, making it crucial for designing treatment processes, monitoring pollution sources, and ensuring compliance with discharge permits.


What is the use of BOD?

Significance of BOD

It determines the rate of respiration in living beings. Measuring BOD gives the COD or Chemical Oxygen Demand of inorganic substances. It indicates the polluting potential of water. BOD is used in the medical and pharmaceutical industries to measure the oxygen consumption of cell cultures.

What is the purpose of a BOD?

BOD provides a measure of the impact of a waste (water) on the oxygen content in a receiving water body.


How is BOD used to measure water quality?

BOD evaluates the amount of biodegradable organic material present in wastewater, effluent and polluted waters. The BOD test reflects the amount of dissolved oxygen (DO) consumed by bacteria while oxidizing these materials over a specific amount of time (usually five days).

How is BOD performed?

In the BOD analysis proper dilutions of samples are prepared. Initial dissolved oxygen readings are then taken. After a five-day incubation period at 20℃ +/- 1℃, Dissolved Oxygen readings are again taken, and calculations are performed based on the difference between these readings and readings taken before incubation.


Biochemical Oxygen Demand (BOD) test: How to do



How do you perform a BOD test?

BOD BASICS
  1. Prepare dilution water.
  2. Prepare seed.
  3. Perform the sample pre-treatment.
  4. Determine dilutions required.
  5. Measure out samples.
  6. Fill bottles with dilution water.
  7. Add seed to those that need it.
  8. Top-off samples with dilution water.


What happens if the BOD is too high?

High BOD and COD can reduce a lake, river or coastal waterway's DO and cause eutrophication. Eutrophication increases nutrients and minerals such as phosphorus and nitrogen, advancing algae and plant growth and decomposition.

What is a good BOD level for water?

BOD, mg/L Water Quality

1 - 2 Very Good: There will not be much organic matter present in the water supply. 3 - 5 Fair: Moderately clean. 6 - 9 Poor: Somewhat polluted, usually indicates that organic matter present and microorganisms are decomposing that waste.


How much does a BOD test cost?

How Much Does a Biological Oxygen Demand Water Test Cost? This test costs $150 and can inform an individual or community about the health of a lake or stream or provide an alert about possible sources of pollution.

What is a normal BOD range?

Typical values

Moderately polluted rivers may have a BOD value in the range of 2 to 8 mg/L. Rivers may be considered severely polluted when BOD values exceed 8 mg/L. Municipal sewage that is efficiently treated by a three-stage process would have a value of about 20 mg/L or less.

What is a high BOD level?

High BOD levels indicate a significant presence of organic pollutants, which can lead to oxygen depletion in water bodies, adversely affecting aquatic life and overall water quality.


What are the benefits of BOD?

Benefits of BOD Removal Wastewater Treatment

Municipalities can use a BOD test to detect water contamination in their public supply to ensure that it is safe for human consumption. Industries need to know their BOD value to determine when treated wastewater is safe for reuse or disposal.

Is low BOD good or bad?

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.

Why do we need BOD?

Why do we need to measure BOD? BOD is an incredibly important parameter because in just one parameter it provides a globally recognised assessment of the water quality. The higher the BOD value, the higher the organic matter in the water which is essentially food available for oxygen consuming bacteria.


What can BOD be used to measure?

BOD (Biochemical Oxygen Demand) is a measure of the amount of dissolved oxygen microorganisms consume while breaking down organic matter in water, serving as a key indicator of water quality and the degree of organic pollution. A high BOD means more oxygen is needed, suggesting more pollution, which can harm aquatic life; a low BOD indicates cleaner water. It's crucial for wastewater treatment to assess efficiency and effluent quality. 

How is BOD removed from wastewater?

Maintaining optimal temperatures is also essential in reducing BOD in wastewater. Alternative methods such as coagulation-flocculation and moving bed biofilm reactors (MBBR) are also used to enhance BOD reduction in wastewater.

How many days do you need to measure BOD?

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 equipment is used for BOD testing?

A dissolved oxygen (DO)meter and probe are critical items needed for the BOD testing. Most new newer DO meters have a built-in barometers, thermometer and on-board software to simplify the calibration process.

What is the best BOD level?

There's no single "optimum" BOD; it depends on the water's use, but for healthy aquatic life and clean water, it should be low (1-5 ppm), while values above 8 ppm indicate significant pollution, and untreated sewage can be 150-300+ ppm, requiring treatment to lower it, perhaps to around 20 ppm for safe discharge. An optimum range for wastewater fish ponds might be 10-20 ppm for maximum production, showing how context matters. 

Can BOD indicate sewage contamination?

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.


Which is better BOD or COD?

While BOD gives insight into the biological degradability of organic matter, COD offers a faster and more comprehensive measure of water pollution. Both parameters play a crucial role in designing treatment plants, ensuring regulatory compliance, and protecting the environment.

What are the 7 water quality parameters?

Parameters that may be tested include temperature, ph, turbidity, salinity, nitrates and phosphates. An assessment of the aquatic macroinvertebrates can also provide an indication of water quality.

Why is BOD done in the dark?

The BOD test is conducted in the dark to prevent photosynthesis from occurring. If the sample were exposed to light, algae present in the water would produce oxygen, which would artificially inflate the dissolved oxygen (DO) reading and underestimate the true oxygen demand.


Do you want a high or low BOD?

For example, higher BOD results in faster depletion of oxygen in the stream, leading to reduced oxygen availability for aquatic life. Consequently, elevated BOD levels cause stress, suffocation, and eventually death among aquatic organisms, similar to the effects of low dissolved oxygen (DO) levels.

How does algae affect BOD?

Algal blooms promote low dissolved oxygen (DO). Algae utilize the oxygen created during the day at night leaving less available for bacteria to consume. The BOD-consuming bacteria promote a more healthy wastewater treatment lagoon.