Water treatment with ozone is an effective method to reduce BOD and COD levels in industrial and municipal waste water. BOD and COD control with ozone can be used in water treatment systems for: Water recycling allowing cost and energy savings to be made on the overall water usage as well as water treatment cost.
How do you maintain COD?
One way to reduce COD in water is to use coagulants and flocculants to bind sludge together. Once they are bound into big enough masses that they can be easily filtered out and deposited into a sedimentation tank for removal. This method does however rely on the use of chemicals, and requires high reoccurring cost.
How do you control BOD?
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.
How is BOD removed from wastewater?
Aerobic BOD (Biochemical Oxygen Demand) removal is accomplished by direct removal of particulate organics and indirectly through the biological activity of the filter. AST’s bead filters can be configured to do both.
What is BOD and COD why it is important to determine in waste water treatment?
Biological Oxygen Demand (BOD) and Chemical Oxygen Demand (COD) are two of the most important parameters to characterise (measure the degree of pollution) of wastewater. BOD, the biological demand for oxygen a source of water has, is the amount of oxygen used by microorganisms to break down organic substances.
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).
How do you test for BOD and COD in water?
Testing for BOD involves incubating a sealed water sample at 20C for five days, followed by measuring the difference in oxygen content before and after incubation. COD measures how much DO is consumed by the oxidation of organic matter and inorganic compounds such as ammonia or nitrite under controlled conditions.
Why does BOD need to be removed?
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.
What causes high COD in wastewater?
COD increases as the concentration of organic material increases. It also increases if inorganic compounds susceptible to oxidation by the oxidant (typically dichromate) are present. Water with high COD typically contains high levels of decaying plant matter, human waste, or industrial effluent.
What is BOD waste management?
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 causes high BOD in water?
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.
Does aeration reduce COD?
Aeration should help reduce the COD in 2 ways. First it may evaporate some volatiles like hexane. Second it will add oxygen to the water speeding up any biological oxidation of the less volatile organics by the bacteria (microbial growth).
Does activated sludge remove BOD?
Aeration is used to operate activated sludge process units and is perhaps the most frequently used process to remove biochemical oxygen demand (BOD) from wastewater.
Can chlorine reduce COD?
Chemically, Chlorination or hydrogen peroxide would reduce the COD. Biologically you could use the conventional activated sludge process, which is an aerobic biological process.
Why is chlorine added to wastewater?
In order for disinfection to be effective wastewater must be adequately treated. Chlorine is the most widely used disinfectant for municipal wastewater because it destroys target organisms by oxidizing cellular material.
What are the methods of disinfection?
Chlorination, ozone, ultraviolet light, and chloramines are primary methods for disinfection. However, potassium permanganate, photocatalytic disinfection, nanofiltration, and chlorine dioxide can also be used. Organic material is naturally present in water.
How do you reduce BOD COD wastewater?
You can reduce COD and BOD by adding hydrogen peroxide to the wastewater solution. The hydrogen peroxide will chemically attack the organics in the wastewater, degrading them and reducing the measured COD and BOD.
How COD is measured?
COD is measured via a laboratory assay in which a sample is incubated with a strong chemical oxidant for a specified time interval and at constant temperature (usually 2 h at 150°C). The most commonly used oxidant is potassium dichromate, which is used in combination with boiling sulphuric acid.
What is the limit of COD?
The chemical oxygen demand (COD) concentration in a treated effluent, if observed to be persistently greater than 250 mg/l before disposal to any receiving body (public sewer, land for irrigation, inland surface water and marine coastal areas), such industrial units are required to identify chemicals causing the same.
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.
Why is BOD important in water quality?
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.
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