What is BOD in wastewater treatment?
Biological Oxygen Demand (BOD) is a chemical procedure for determining the amount of dissolved oxygen needed by aerobic biological organisms “bio-bugs” in a body of water to break down organic material present in a given water sample at a certain temperature over a specific time period.
What is BOD and COD in waste water treatment?
The biochemical oxygen demand (BOD) represents the amount of dissolved oxygen (DO) consumed by biological organisms when they decompose organic matter in water. The chemical oxygen demand (COD) is the amount of oxygen consumed when the water sample is chemically oxidised.
Why is BOD value important in wastewater treatment?
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. Sewage with high BOD can cause a decrease in oxygen of receiving waters, which in turn can cause the death of some organism.
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.Apr 10, 2020
Which is better BOD or COD?
COD is normally higher than BOD because more organic compounds can be chemically oxidised than biologically oxidised. This includes chemicals toxic to biological life, which can make COD tests very useful when testing industrial sewage as they will not be captured by BOD testing.Jan 12, 2022
How BOD test is done?
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 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.
Does chlorine reduce BOD?
BOD reduction: Chlorine accomplishes BOD reduction by oxidation of organic compounds present in wastewaters. 4. Oxidation of metal ions: Metal ions which are in reduced state are oxidized by chlorine (e.g., ferrous to ferric ion and manganous to manganic ions).
Does pH affect BOD?
Bacteria that treat waster water to reduce the COD and BOD, are extremely sensitive to pH! So pH can also have a huge effect on activated sludge COD and BOD reduction rates.
What BOD means?
Biological Oxygen Demand (BOD) refers to the amount of dissolved oxygen that aerobic organisms need in order to break down organic material in water over time. Its high value indicates the intense level of microbial pollution.
How do you reduce BOD in water?
These are the best practices for reducing BOD and TSS that facility managers should know:Focus on removing TSS from wastewater first. ... Get a properly sized EQ tank. ... Control the pH of the waste stream. ... Install a modern plate pack DAF made of stainless steel or plastic. ... Use a regenerative turbine air dissolution pump.More items...•Aug 16, 2018
What happens if BOD is low?
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 is BOD in wastewater?
Industries that discharge wastewater into municipal sanitary sewers or waterways are facing strict regulations on levels of biological or biochemical oxygen demand (BOD). Solid materials in wastewater can consist of organic and/or inorganic materials and organisms.
What is the purpose of biological oxygen demand?
Biological Oxygen Demand (BOD) is a chemical procedure for determining the amount of dissolved oxygen needed by aerobic biological organisms “bio-bugs” in a body of water to break down organic material present in a given water sample at a certain temperature over a specific time period.
What is a BOD in wastewater?
Biological Oxygen Demand (BOD) is a chemical procedure for determining the amount of dissolved oxygen needed by microorganisms to break down organic matter.
What is the purpose of oxygen in BOD?
In a conventional BOD Wastewater Treatment process, microorganisms use oxygen to break down organic compounds. The microorganisms essentially consume the organic matter, but there must be enough oxygen in the water. If there isn’t enough oxygen in the water, the microorganisms will die. Diffused Air supplies the aeration tank with an ample amount of oxygen. The organic compounds in the wastewater provide the microorganisms their “food”.
How does a sludge thickener work?
When there is enough wastewater in the sludge thickener, the slurry from the tank is pumped into the Filter Press. The filter press separates the liquids and solids using pressure filtration. Sludge Cake will form between the filter plates, where it can be safely removed and easily discarded. The excess water is returned to the Initial Settling Tank.
Where is wastewater collected?
Wastewater is collected in the Initial Settling Tank or the Primary Clarifier . The main function and purpose of the Initial Settling Tank is to make the wastewater homogeneous, and it allows for solids to settle to bottom of the tank forming sludge. The sludge collect is removed and piped over to the Sludge Thickening Tank.
What is the purpose of a clarifier?
Clarifier. After the wastewater is treated in the aeration tank, it is transferred to the Clarifier or the Secondary Clarifier. The Clarifier will remove the excess microorganisms ( Activated Sludge ), and the effluent (clean water) that flows to the top will be discharged or transferred for further polishing.
Where is the waste activated sludge collected?
The Waste Activated Sludge from the clarifier is collected in the Sludge Thickener. The thickening tank will provide additional solid-liquid separation. Any liquid overflow will be returned to the settling rank. The thickened sludge will be processed by the Filter Press .
Does Met Chem offer start up?
Met-Chem can offer start-up and installation as an additional option. We can provide full support as you get your system up and running. We have installation technicians and technical representatives that we can send to your facility to make sure the system is running as it should.
Why is BOD important?
BOD is a crucial factor in refining wastewater. The bacteria are important for breaking down substances, however too much BOD can cause unwanted amounts of bacteria. It can also drain receiving waters of oxygen which can kill fish and harm the environment.
Why is it important to remove solids from wastewater?
The importance of removing solids and BOD in wastewater is just as important to a small office park as it is to an entire city. Wastewater treatment utilizes several delicate chemical processes to achieve an acceptable quality of water, which is analogous to an acceptable quality of life. Wastewater contains many elements which break down ...
Is a septic system aerobic or anaerobic?
Many septic systems have both an aerobic and anaerobic process, while others focus on reducing the need of BOD altogether.
What is BOD5 in wastewater?
Typically, municipal wastewater treatment plants will use BOD5 as a measure of the organic concentration into, and through, the wastewater plant. Industrial wastewater systems will more often use COD to measure the organic concentration moving through the treatment plant. In my experience, I see TOC being used much less often (rarely) ...
What is the BOD5 test?
The BOD5 test measures the oxygen consumed by microorganisms as they oxidize (consume or eat) the soluble organic matter in the wastewater. But the BOD5 test is a somewhat unreliable means of determining the amount of organic matter present in water. The test measures only the approximate amount of oxygen that will be required ...
What is the purpose of a wastewater test?
The test measures only the approximate amount of oxygen that will be required (absorbed or consumed) by a wastewater when it is exposed to air or oxygen for an extended period of time. Toxic substances in the wastewater inhibit or even prevent bacterial growth and, therefore, oxidation of the organic matter.
How long does it take to test for organics in wastewater?
The often highly variable chemical composition and strength of industrial wastewater requires a much more rapid method for measuring the organic concentration, hence the use of the two hour COD test or, in some plants, the 30 minute TOC analysis.
BOD Compliance
High concentrations of BOD in wastewater can lead to regulatory issues. By implementing a system to effectively reduce the BOD in the wastewater stream your company will have the ability to remain in compliance and reduce risk. This will save your company regulatory costs.
COD Compliance
Effluent with high concentrations of COD can lead to compliance issues. Our wastewater systems can significantly reduce the Chemical Oxygen Demand in your wastewater. We have saved our customers surcharges and headaches by reducing their COD wastewater.
Treatment Solutions
The two recommended aerobic treatment and reuse technologies include Membrane Bioreactor (MBR) Systems and Moving Bed Biofilm Reactor (MBBR) Systems.
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What is COD in water?
COD, the chemical demand for oxygen a source of water has, is the amount of oxygen required to break down organic substances chemically and convert them to CO 2 and H 2 O. It is also expressed in mgO 2 /L, and the higher the COD, the more polluted the water is.
How much COD is in water?
The COD in industrial water may be 50 – 2,000 mgO 2 /L, although it may reach 5,000, depending on the type of industry. The main difference between BOD and COD is that COD measures all organic material, while BOD only measures organic material which is or can be biologically degraded.
What is COD in biology?
Chemical Oxygen Demand (COD): COD is defined as the oxygen equivalent of the organic portion of the sample that is susceptible to oxidation by a strong chemical oxidant potassium dichromate K2Cr2O7, Biochemical Oxygen Demand (BOD) is a chemical procedure for determining how fast biological organisms use up oxygen in a body of water.
What is the purpose of COD?
In environmental chemistry, the chemical oxygen demand (COD) test is commonly used to indirectly measure the amount of organic compounds in water. Most applications of COD determine the amount of organic pollutants found in surface water (e.g. lakes and rivers), making COD a useful measure of water quality.
What is the purpose of the Biochemical Oxygen Demand?
Biochemical Oxygen Demand (BOD) is a chemical procedure for determining how fast biological organisms use up oxygen in a body of water. It is usually performed over a5-day period at20° Celsius. It is used in water quality management and assessment, ecology and environmental science.
Is BOD a pollutant?
It is listed as a conventional pollutant . BOD is similar in function to chemical oxygen demand (COD), in that both measure the amount of organic compounds in water. However, COD is less specific, since it measures everything that can be chemically oxidized, rather than just levels of biologically active organic matte.
