In any wastewater treatment process today, people only measure the BOD number of the wastewater after treatment. Is it effective as required? BOD is one of the important indicators that helps evaluate wastewater treatment quality accurately and objectively. So what is the BOD index and what does it mean? Let’s Duc Binh Microbial Products refer to the article: What is BOD index and what do they mean?
1. What is the BOD index?
BOD is an acronym that stands for the phrase Biochemical (or Biological) Oxygen Demand – also known as biological oxygen demand. This is a commonly used concept to talk about the amount of oxygen that organisms consume in anoxic environmental conditions. At a certain temperature when they need to decompose organic substances necessary for life.
Photo 1: BOD is an important index in evaluating the quality of wastewater after treatment
In the water environment, we cannot observe oxygen with the naked eye. Everyone knows: water contains air but it is very difficult to observe this. In fact, any water environment, typically pond water, lakes, rivers, and streams, contains a certain amount of oxygen.
Although this percentage is very small, only about 10 oxygen molecules exist based on the condition of 1 million water molecules but it is an extremely important balance in nature. The presence of oxygen molecules in water is an essential factor that helps aquatic organisms survive and develop.
2. Correct understanding of BOD numbers
The role of the BOD index
Water quality in an area is expressed through the existence of dissolved oxygen inside. Therefore, in the water quality management process, identifying the potential impact of organic substances on dissolved oxygen concentration is an important task. Accordingly, the BOD index measures the level of decomposition of organic substances existing in the water environment.
What is the main purpose of using BOD?
Difficult environmental conditions such as hot summer weather or the impact of human life will significantly reduce the amount of dissolved oxygen in water. Chemical fertilizers flowing into water sources also affect the BOD index. That may be one of the reasons that makes the life of microorganisms in water and aquatic species become more difficult.
However, water quality analysis is proposed with the goal of understanding the level of influence from the decomposition of organic matter in water by bacteria and microorganisms when they consume oxygen in this process. This is also the role of the BOD biological oxygen demand measure.
So, what is the role of BOD and how important is this index? BOD is an important metric used to measure the level of oxygen consumption by aerobic bacteria during the process of removing organic waste from the water environment.
The stability of the amount of organic waste in water is thanks to this natural decomposition process. BOD is an index used in wastewater treatment systems to evaluate output quality and determine the level of water pollution.
Photo 2: BOD reflects the level of organic waste pollution in water
For those working in chemical-related professions, especially environmental research, BOD is one of the important indicators that are mentioned often. BOD is also particularly important in the issue of domestic organic waste treatment. So in general, what is the chemical meaning of the BOD index?
3. What is the meaning of BOD index in chemistry?
What is BOD index we mentioned above. This is a concept used to refer to biochemical oxygen demand – a necessary need for the decomposition of organic matter by microorganisms. This process takes place regularly according to the following chemical reaction:
Organic matter + O2 -> CO2 + H2O + new cells + intermediate products
In this case, what is the meaning of BOD? It reflects the amount of organic waste that exists in the water environment that can be decomposed by microorganisms living there.
In short, BOD is one of the important indicators used to test whether the quality of output wastewater meets standards or not, for the purpose of protecting the environment. With the results received from the BOD index, the management board will choose the most optimal wastewater treatment method, that meets the requirements.
If the results received from the BOD index are very high numbers, it means that organic pollution in water sources is at an alarming level. Therefore, we need to quickly apply biotechnological measures to thoroughly treat it, avoiding potential risks that may occur if left for a long time.
4. BOD parameters of some types of wastewater today
Based on understanding the chemical BOD index, people need to clearly know the BOD parameters of some common types of wastewater today:
- Domestic wastewater: BOD parameters from 100 – 200 mg/L
- Wastewater in seafood processing: BOD parameters from 2000 – 5000 mg/L
- Wastewater in beer production: BOD parameters from 800 – 2000 mg/L
- Wastewater in paper mill: BOD parameters from 2000 – 3000 mg/L
- Wastewater in rubber production: BOD parameters from 3000 – 10000 mg/L
- Wastewater in plating: BOD parameters from 300 – 1000 mg/L
- Wastewater in textile dyeing: BOD parameters from 500 – 3000 mg/L
- Wastewater in livestock: BOD parameters from 3000 – 5000 mg/L
- Sugar cane wastewater: BOD parameters from 1600 – 5000 mg/L
5. BOD test method
Photo 3: What is the testing method with BOD index?
The testing method with BOD measurement index is conducted by collecting a sufficient test water sample from the corresponding water source. Mix the test sample with an amount of deionized water with oxygen reaching saturation level. Add a specified amount of necessary microorganisms to the sample, measure the amount of dissolved oxygen in the water and then close the lid.
The purpose of covering the lid is to prevent oxygen from continuing to enter and dissolve in the water. Then, keep the sample in the dark with an ambient temperature of 20 °C to avoid photosynthesis that would increase the initial expected oxygen content. Conduct the experiment for 5 days and then end with re-measurement of dissolved oxygen. The BOD index is the difference between the initial amount of dissolved oxygen and the amount of oxygen measured after the experiment.
In addition to concerns about the BOD index, you should also refer to a few other related indicators that play an important role in assessing the quality of output wastewater. Those are COD, DO and TSS indicators.
⫸ See more: What are microbial products for wastewater treatment? How to use most effectively
⫸ See more: How to treat pig farming wastewater (pig)
⫸ See more: Microbiological sludge What is it? The role of microbial sludge in wastewater treatment
⫸ See more: Application biotechnology in water treatment waste? advantages and disadvantages
6. What is COD index?
COD stands for the full phrase Chemical Oxygen Demand – reflects the total amount of organic matter existing in the water environment, including the amount of oxygen needed to oxidize chemical compounds in water in both inorganic and inorganic form. organic.
The COD index is commonly used for the purpose of non-directly measuring the volume of organic compounds existing in the water environment. Talking about the COD index, we see that it has a similar role to the BOD index. Both of these indicators are used to determine organic compounds in water. This is also the close relationship between COD and BOD.
Photo 3: What is the testing method with BOD index?
7. What is DO index?
DO stands for Dissolved Oxygen – reflecting the amount of dissolved oxygen needed in the water environment for the respiratory activities of aquatic organisms here. Therefore, the DO index is used to determine the level of organic pollution in water sources.
The average free oxygen concentration in water is about 8 -10 ppm. Whether this number fluctuates or not depends on chemical decomposition, algae photosynthesis, ambient temperature, etc. To determine the DO index accurately, people use one of the following two methods:
- Winkler method (chemistry)
- Dissolved oxygen electrode method – oxymeter
8. What is TSS index?
TSS stands for Turbidity & Suspended Solids – total suspended solids that exist in the water environment. TSS index is often measured with a turbidity meter. In particular, turbidity is the result caused by the contact between light and suspended substances in water, microorganisms and organic substances that exist in the same environment.
Some typical substances that can be mentioned here are sand, clay, algae,… A collection of suspended solids will scatter light and absorb it again to reflect. The way it is done depends on the size, shape and composition of the suspended particles.
9. Some solutions to help reduce the BOD index
As mentioned above, a high BOD index means that the water source has been polluted and is no longer able to clean itself because microorganisms need a large amount of oxygen to decompose organic matter but this is not the case. Therefore, reducing the BOD index is especially necessary at this time. Below are some solutions people can apply:
- Primary treatment: The goal of this method is to remove large solid wastes suspended in water or grease by sedimentation or filtration
- Biological treatment: This is an effective treatment option recommended by experts. People use biological products poured into water to make beneficial microorganisms work, speeding up the process of decomposing organic matter as a food source. Of course, when active, microorganisms need oxygen to survive. Therefore, we need to supplement dissolved oxygen in water
- Sludge activation: Using an Aerotank to allow microorganisms to grow and decompose organic matter
- Biological filter tank: Uses Biofilm material to let microorganisms attach to and decompose organic matter in wastewater
- Biological pond: Take advantage of aquatic plants to absorb nutrients in the water and produce oxygen.
- Chemical treatment: Use chemicals to create precipitation to absorb or oxidize organic substances in water.
- Physical treatment: Apply methods such as: Filtration, reverse osmosis to remove contaminants.
In addition to the above measures, in order to contribute to reducing BOD at the source, people need to: Recycle waste, reduce the use of products that are difficult to decompose, treat industrial waste before being discharged into the environment, raise community awareness about protecting the water environment, and economically use clean water…
We have learned about what the BOD index is, how important is this index for evaluating the quality of wastewater after treatment how? In addition, people also refer to more concepts of a few other important indicators. Hopefully this article will be a useful reference source for you. For more information about the operation of current wastewater treatment systems, you can visit https://chephamvisinh.vn/ >
Learn more: Causes of fungal diseases in fish and effective ways to prevent and treat them
Contact information
Duc Binh Biotechnology Company Limited
MST: 0108433217
Address: 57 Lane 64 Kim Giang, Khuong Dinh, Hanoi
Phone number: 024.66.55.46.86
Transaction office
Duc Binh Microbial Products – Center for Research and Application of Biological Products specializes in research, production and application of product lines: Probiotics, septic tank yeast, wastewater treatment yeast, aquatic yeast, biological products…
Address : 1B Alley 774 Kim Giang, Thanh Liet, Hanoi
Phone number: 0934.214.579
Hotline: 024.66.55.46.86
Email: chephamvisinhungdung@gmail.com
Website:https://chephamvisinh.vn
